FIVE
Harvesting On-Site Resources

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All sites are endowed with multiple flows of energy and resources that can be used as part of a sustainable design.

Basics of On-Site Resources

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Fig. 5.1. Resource inputs and outputs.

A sustainable building will optimize use of renewable resources and minimize waste. Integrated design makes it possible to harvest many on-site resources (sun, wind, rain) to reduce operating costs and to minimize the external costs of off-site waste disposal or releases. Harvesting on-site resources and using resources more wisely can help improve the quality of life for everyone and can rebuild ecosystem health. This section reviews the harvesting of available resources (water, energy, food scraps, yard clippings) and minimizing waste. There are two key concepts to remember:

1. A waste is an unrecognized resource (waste = food).

2. There is no “away” (where wastes will disappear to).

Resource flows can be understood by developing a better picture of their pathways through the home, neighborhood, and community. Very few studies have been done to understand these flows, their costs, and the opportunities they provide. Many reports are based on largely incomplete and inaccurate information. The garbology research project at the University of Arizona (beginning in 1973) has provided some clear information on what is used and discarded and how it behaves after it is sealed in a “sanitary” landfill. What people say they do, and what they really do, was also revealed. The amount of food waste was found to be double US EPA estimates.

Positive Impact Development

Land development in the United States has historically been catastrophic for nature and ill suited for human health and well-being. As a result we are broke, fat, and unhappy. But development doesn’t have to be evil. If we frame the question properly and count the costs and benefits carefully, we can create developments that are good for people and help protect and restore the function of natural ecosystems. Achieving this requires a very different approach to development, beginning with careful analysis of the ecological setting, the economic matrix, and the social structure, as well as an integrated, holistic vision for the future.

Although we depend on natural systems for the air we breathe, the food we eat, the water we drink, and the materials we use to build our homes, we have lost touch with this connection to nature. Water now comes from the faucet; food comes packaged and prepared; energy flows from the wall socket; and wastes are simply flushed or hauled away. But natural and managed ecosystems still provide us with the requirements for life, and every one of us has an impact on our planet. If we don’t take more from the earth than it has to offer we can continue to prosper; but are we taking more than we can or should?

The growing awareness of serious problems with global and local ecosystem stability and resource availability is encouraging new consideration of the sustainability of our current lifeways and communities. This has been addressed with eco-footprint calculations and sustainability indicators. Both are of value, but both are challenging to do well. Eco-footprint calculations are particularly effective for awareness building, while sustainable area budgets (refer to chapter 6, R. Levine) and sustainability indicators can be more useful for management and monitoring. Most approaches have emphasized environmental concerns, but economic and social concerns may be equally important.

To develop appropriate and sustainable solutions, we need to understand the causes of these problems, not just the symptoms. As British economist A. C. Pigou (1920) noted early in the last century, the market will fail unless it includes all costs. The market today considers only a small fraction of the total transaction cost, leaving many “externalities” out of the picture. These externalities include the costs of pollution, disease, and damage to vital ecosystem services.

These externalities are integral costs of goods and services, often exceeding the current costs. In many cases we have not studied them, because we do not want to know the answer. For an excellent review of the issues involved in calculating the external costs of automobiles, see Bainbridge (2009*). Some critics suggest that users currently pay only 10 percent of the true costs for using automobiles in the United States. These enormous subsidies benefit the auto users, the automakers, oil companies, and highway builders; but taxpayers who do not use cars and future generations pay the price.

If true costs were known, many current market transactions would not occur, resources would be conserved, pollution would virtually vanish, and we would face a much more hopeful, secure, and sustainable future. To reduce consumption of nonrenewable resources and limit adverse environmental and social impacts, we need to understand the true cost of products throughout their full life, from the cradle to the grave (made, used, disposed) or cradle to the cradle (made, used, recycled, reused, or returned to nature). This is the goal of most sustainability reporting and environmental management systems, from the Eco-Management and Audit Scheme to the Global Reporting Initiative and ISO 14000 series.

For monitoring our community sustainability, we might start with a set of indicators that we will monitor. Choosing the appropriate number of indicators can be a challenge, for although we could perhaps reach four hundred, such a large number would become burdensome; for general application it appears that ten to twelve indicators for each sector (social, economic, environment and perhaps institutional) will suffice. This can yield a total of about thirty or forty indicators, which can be easily presented in graphic form to decision-makers and the public.

Despite the growing recognition of the problem, and recent efforts such as the Sustainable Sites Initiative and Low-Impact Development, the planning process has failed to create sustainable communities. With a few notable exceptions, such as Village Homes, the development process typically creates unsustainable homes, support systems, and ways of living while providing inadequate financial support for costly infrastructure services, destroying local ecosystems, and disrupting local hydrologic cycles. Starting earlier and working with a more complete land development model that includes human, economic, and ecological health as key criteria can shape a more humane and sustainable landscape.

What Would It Take?

Long-term sustainable development will require a new approach that embraces

Some Definitions

How we manage resources depends on how we understand and define them. Here are some key issues and terms:

Context

The twenty-first century faces a series of resource crises as serious as our energy and climatic crises. The resources involved are all essential to agriculture and related to our consumption, settlement, and building patterns. Using passive design approaches that combine use, production, recycling, and efficiency at the scale of buildings and neighborhoods can help relieve these situations.

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Fig. 5.2. Resource crises of the twenty-first century.

Energy and climate have been in a crisis state long enough to be widely understood; the problems of freshwater supplies are generally recognized as well. Resource crises 4 and 5 in figure 5.2 are less well known. Phosphorus and fixed nitrogen are essential to plant growth and therefore to agriculture. Phosphorus deposits that are easily exploitable are diminishing. As a result, phosphate costs have increased 500 percent during the last ten years. As with oil, many nations have depleted phosphate mines and now must rely on imports. One of the best sources of phosphate is human waste, and restoring a sustainable phosphorus cycle is important. One-half of that is available in urine, which is easy to recover if separated from solid waste. Modifying toilets and toilet habits to collect urine is a passive approach to tapping into a resource that is also rich in fixed nitrogen.

Advanced cultures have a remarkable history of sophisticated development of on-site resources, with periods of great success followed by periods of stress and collapse. We are not immune to the historical patterns illustrated in figures 5.4–5.7. Creativity cannot stop with the development of one aspect of infrastructure, because we live in a dynamic world that is becoming more dynamic with time, as illustrated by crises 1, 2, and 3.

Much of our present infrastructure has been developed in a reductionist state of mind that ignores connections between parts. However, in reality everything is intimately connected. The chart in figure 5.5 shows this connection between water use and energy in the United States. In California, 20 percent of energy use is water-related.

We must reconnect pieces that have to date been designed in isolation. This is why the passive approach to harvesting on-site resources is so important to our present situation and our continuance as an advanced culture.

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Fig. 5.3. US water use.

300–1200

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Fig. 5.4. Petra is located in what is now Jordan. The Nabatean people who lived in the Negev desert in Petra were probably the most sophisticated rainwater harvesters the world has ever known. They used rainwater catchments for drinking, washing, cooking, and farming. Petra prospered in an area with less than 5 inches of rainfall per year.

800–1500

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Fig. 5.5. Angkor is located in what is now Cambodia and was the capital of the Khmer empire. It was the largest pre-industrial city in the world with a population of 1 million and an area similar in size to present-day Los Angles (500 square miles). This was made possible by sophisticated technology and building for managing and harvesting water for use during the dry season in this tropical climate. (a) Plan; (b) Angkor Wat temple; photo: Chris Yip; (c) aerial photograph.

1375–1521

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Fig. 5.6. Tenochtitlán, now known as Mexico City, was the capital of the Aztec empire and built in the shallow part of Lake Tetzcoco, one of five interconnected lakes that occupied much of the valley of Mexico. The city was dependent upon an elaborate infrastructure of causeways, dams, sluice gates, canals, dikes, and chinampas. The chinampas, a highly efficient system of marshland agriculture, provided more than half the food required for the city’s 200,000-plus inhabitants.

1930–1985

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Fig. 5.7. In the western UnitedStates, huge dams and related water projects created massive irrigation systems with inexpensive water and cheap electricity, resulting in conspicuous consumption. Las Vegas is the most extreme example. However, this unsustainability is becoming more and more obvious. Nevada leads the country in the rate of bankruptcy, and Las Vegas faces water scarcity. (a) Siltation is the main enemy of large dams and the reason, it is thought, that dams will outlive the lakes they create. In the first thirty-five years after the Hoover Dam was built, Lake Mead filled with more acre-feet of silt than 98 percent of the reservoirs in the United States are filled with acre-feet of water. (b) Las Vegas water extravagance in a hot desert environment.

Solar Hot Water

Hot Water from the Sun

One of the most efficient and affordable solar applications is a solar water heater. These are three to four times more efficient than photovoltaic systems and cost from one-fifth to one-tenth as much to install. At the turn of the twentieth century (1900), solar hot water was in the ascendancy in the United States, and by the turn of the next century (2000) solar hot water was a fact of life in Cyprus, with 95 percent of homes heating water with the sun, and Israel, with 90 percent. But by 2000, solar water heaters had virtually disappeared in the United States, with less than 2 percent of homes so outfitted. Hawaii is leading the way by now requiring solar hot water for all new homes. China is installing seven million solar water heaters a year, while the United States is installing less than thirty thousand. Federal and state credits are once again available in some cases; still, the obstacles include not just cost but also ignorance, the pernicious effects of public/private regulation, and management of the utilities and subsidies for fossil fuels.

Hot water is a major energy demand in most homes, as much as 20 percent of total energy. Hot-water demand tends to have two peaks, a morning peak (7–10 am) and an evening peak (5–9 pm).

A well-built, properly installed system can be very cost-effective. For example, a building-integrated integral-collector hot-water system installed in Village Homes in Davis, California, is now in its thirty-third year of service. One of the six tanks recently developed a small leak and was bypassed at very low cost. To date, this system has provided about 290 mBTU of solar energy for about a penny per kWh equivalent.

While a commercially built and installed system may cost $2,000 to $8,000, an integral-collector system can be built for less than $500 by a crafty homeowner. Even the more expensive systems make sense. Although payback in the simplest sense may require ten to twenty years for expensive systems, as we start to consider all the costs and benefits we will soon see solar water systems on most homes and many commercial buildings. In most areas the cost comparison with backup electricity is very positive, and even when compared with gas solar hot water is desirable.

Solar heating water typically costs only 1 to 8 cents per kWh equivalent, compared with fossil fuels at 6 to 20 cents per kWh. But to get more systems installed, we need to overcome the regulatory deadlocks that keep utilities from investing in solar hot water. We need to provide mechanisms that reward utilities for installing solar hot-water systems on a large scale. By installing a thousand at a time instead of one at a time, the cost can be reduced significantly. One Florida utility will install a solar water heater, and then charges for the hot water at standard prices as the solar energy is delivered. This has become much easier today thanks to improvements in telemetering. We also need to accelerate real-time metering and time-of-use-based costs; these make solar hot water look even better, because they help reduce demand during the critical August afternoon peak periods when energy from the grid is more costly.

Collector Options

Integral-Collector Systems (ICS)—Temperate and Warm Climates

In their simplest form, these solar heaters are little more than a black tank set in the sun in an insulated box with a double-glazed window. The cost is minimal and reliability is excellent. Service life is very long because temperatures are moderated by the mass of the tank. The relatively low temperature of the collector also improves efficiency because heat losses from re-radiation and conduction are reduced. An early study in California by the University of California (Brooks, 1936*) showed that an integral system outperformed flat-plate collectors. ICS systems are also called batch, bread box, and integral water heaters.

The mass of the water in the system helps protect it from freezing and the extreme high temperatures that can harm materials in other collectors. This leads to very long life for tanks and materials. An ICS system using a glass-lined steel tank may last thirty to fifty years, while a gas water heater averages only about seven. A solar water heater also reduces stress on the gas water heater and improves service life.

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Fig. 5.8. Most variations in hot-water systems occur in the tank configurations shown here.

The standard integral-collector solar water heater brings cold water into the solar heater tank through a side inlet near the bottom or through a dip tube that enters the tank at the top and discharges unheated water near the bottom, heats it, then moves it along to a backup heater—which can be fueled by gas, electricity, or wood—through an outlet near the top where the water will be warmest. An instantaneous gas water heater with thermostat controls works well as a backup.

During the summer months—or where it is warm and sunny year-round—the backup heater can often be turned off. David’s three-tank integral solar water system provided full solar hot water for nine months of the year in Davis, California. A simple ICS in Germany provided 60 percent of the annual hot water (sometimes referred to as a solar fraction of 60 percent).

Integral systems lose energy at night even with selective surfaces (as you will recall from chapter 1, these have high absorptivity and low emissivity) on the tank and good glazing systems. This makes them best for people who like to shower in the evening after work. It also reduces performance in cool seasons and increases risk of freezing in winter. Most integral systems should be drained in winter in cold climates. The pipes are often most vulnerable to freezing. Experiments in Europe suggest that collectors with less than 2 gallons of collector storage per square foot of glazing are more at risk of freezing. These recent studies suggest that up to 20 percent of the water in the collector can freeze without damaging the tank.

Building-integrated integral systems offer the lowest freeze risk and easiest long-term maintenance in new homes because they do not have exposed pipe runs and do not need to be pulled off the roof for reroofing. ICS solar heaters use waterline pressure for circulation, eliminating the need for expensive pumps and/or controls.

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Fig. 5.9. (a) Integral-collector system. (b) Harpiris Suncache integral-collector system (ICS). (c, d) Building-integrated integral-collector system.

Flat-Plate Collectors—Warm or Cool Climates

A flat-plate solar thermal collector usually consists of copper tubes fitted to a flat absorber plate. Common setups include either a series of parallel tubes connected at each end by two pipes, the inlet and outlet manifolds, or a serpentine pipe. The pipe-collector assembly is contained within an insulated box and covered with low-iron tempered glass. These collectors may operate by thermosiphon action, with circulation provided by simple warm water rising to the collector tank, or with controllers and pumps. Simple thermosiphon systems with the water storage in an insulated tank above the collector are very common in many areas of the world. The pumped systems can be made more sustainable by using a solar panel to power the pump.

Systems that operate with water can freeze as a result of cold air and night sky radiant cooling. Freeze protection for these systems may be provided by draining the system in winter. In swing seasons, a drain-back design can reduce risk of freezing. With these collectors, the system is dry except when it is working. Drain-down control valves that would drain the collector when temperatures drop to dangerous levels have not proven very reliable. Flat plates can also use antifreeze solutions to move heat to a heat exchanger in the water heater or a solar tank that is connected to the solar water heater with a heat exchanger. When flat-plate collectors are empty, they get very hot, and service life can be limited. In some situations, flat plates may clear themselves of snow better than the highly insulated evacuated tube collectors, so check with local solar hot-water installers and users to see what will work best for you.

Thermosiphon systems are very simple and have a long service life, but active systems with controls and sensors are more likely to need maintenance. Although they may work twice as long as a gas-fired appliance, active systems have tended to fail after ten to fifteen years. Repairs are usually simple, but often not made. The quality of controls and pumps is improving thanks to European investment, regulations, and higher expectations, but systems with high-quality pumps, controls, and heat exchangers can be costly. The added complexity reduces energy performance over the lifetime of use as manufacturing and materials costs of pumps and controllers are added to operating cost, but these can be a good choice for many homeowners and businesses.

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Fig. 5.10. Thermosiphon flat-plate collector and PV array.

Evacuated-Tube Collectors—Any Climate, Best in Colder Climates

Evacuated-tube collectors (ETCs) were invented in the United States but first put into widespread use in China and Europe. An evacuated-tube collector includes a row of parallel transparent glass tubes that are evacuated like a vacuum bottle. They can be run in several different configurations, including single and double tube. In the double tube, the vacuum is in the area between the tubes. These can be set up in several different configurations, including heat pipe, U-pipe, and direct-flow systems. These collectors include an absorber and a working fluid that transfers the energy from the tube to the collector tank or a manifold with another fluid that transfers energy to the storage tank. Very high temperatures can be reached, so a tempering valve is essential. The high temperatures also make these a good backup for space heating using a fan coil or hydronic heating system, suitable for almost any climate.

The most common designs today use a “heat pipe” configuration to transfer energy to a manifold above, which then transfers the energy to the storage tank. These vacuum tubes are made with borosilicate glass and are expensive to manufacture. Borosilicate glass is tough and resists most impacts from hail and wind-driven debris. Many are modular, which makes it possible to assemble the collector on the roof. It also makes repairs easier; many can be repaired without draining the system.

These evacuated-tube systems perform well even in cold temperatures but may not provide an advantage in milder climates. Tests in Sydney, Australia, suggest the performance of water in an ETC system was about the same as a flat-plate collector (a flat plate may cost only a third as much per m2). The solar fraction in Sydney rose from 45 percent winter to 90 percent in summer, while it was 92 percent year-round in Darwin.

Costs are relatively low for Chinese models, but European systems can be pricey. Competition should increase quality and availability and reduce prices. In China, household hot-water demand is small and sizes are small. The cost is also low, as low as $100/m2 with an average cost about $235/m2, while German systems were $700–$1,700/m2. These systems, primarily evacuated tube, will often provide 100 percent of hot-water heating needs during the summer and about half in the winter.

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Fig. 5.11. Evacuated-tube collector.

Absorber Systems

A simple absorber system collects energy from the sun without glazing or an insulated box. These are the most commonly used systems in the United States, installed primarily for pool heating. These are often made of polypropylene and have performed well. We have also known people to develop a solar hot-water system using a food-grade dark-colored hose coiled on the roof. Not elegant, but inexpensive and effective.

What Kind?

The best system for a particular site will depend on the water-use pattern, the sun, the climate, and the user. Simple low-cost systems can have the best performance per dollar, but may require more participation and involvement. A home-built integral-collector system can be very effective and will last a long time if well made, but may have to be drained in winter. In a cooler climate, a high-quality commercial flat plate or an evacuated-tube collector installation should be trouble-free. Austria, with a fairly cold interior climate, for example, has very widespread use of solar hot-water systems, primarily flat-plate collectors. The ETC can perform well even in much colder climates.

How Big?

If you wish to develop a better understanding of sizing or plan to build and install your own system, you can develop a chart of daily use by looking at your gas-use pattern in summer (if you have a gas heater) or by maintaining a hot-water-use diary. Then refer to performance data for commercial systems from the Solar Rating and Certification Corporation and climate and sun data to fine-tune the sizing. Your supplier and installer can help you figure out the best type and size of collector and storage tanks for your use pattern and climate (see Gil and Parker, 2009*). Local experts can also help you determine the best kind of backup system, perhaps a gas-fired on-demand heater.

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Fig. 5.12. Installed collector area in Austria.

Efficiency First

As with most other sustainable systems, the first step should always be improving efficiency and reducing use of hot water. Can you reduce hot-water demand by improving showerheads? Installing a horizontal-axis clothes washer that uses less water? Hand washing dishes with care instead of using a dishwasher? Using cold or warm water to wash most clothes?

Rules of Thumb

You can ask about the local “rules of thumb” to check on your calculations or commercial recommendations. In the Sunbelt, a recommendation might be for 1 square foot of collector for every 2 gallons of storage. In colder areas, it might be 1:1. In Davis, California, a good rule of thumb for integral-collector systems was for at least 30 gallons of collector capacity per person, with 2 to 3 gallons of tank per square foot of glazing. For Florida residences with a dishwasher and an automatic clothes washer, a rough rule of thumb is 10 square feet of flat-plate collector area per person, with 20 gallons of water storage per person.

A wide range of solar incentives and support programs are offered by states and the federal government in the United States. Other countries also offer very effective supports and assistance to install solar hot water. In Hawaii, Israel, and some areas in China, solar hot-water systems are required. DSIRE (www.dsireusa.org) is a comprehensive source of information on state, local, utility, and federal incentives and policies that promote renewable energy and energy efficiency. Established in 1995 and funded by the US Department of Energy, it is an ongoing project of the North Carolina Solar Center and the Interstate Renewable Energy Council.

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Fig. 5.13. Solar waters heaters in Athens, Greece. Greece leads the EU in solar water heater installations.

Electricity Production by Steve Heckeroth

We know that relying on coal, oil, and natural gas threatens our future with toxic pollution, global climate change, and social unrest caused by diminishing fuel supplies. Instead of relying on unsustainable fossil fuels, we must transform our economy and learn to thrive on the planet’s abundant supply of renewable energy.

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Fig. 5.14. Available renewable energy resources compared to nonrenewable energy resources.

Our best and easiest option is solar energy, which is virtually inexhaustible. Most important, if we choose solar we don’t have to wait for a new technology to save us. We already have the technology and energy resources we need to build a sustainable, solar electric economy that can cure our addiction to oil, stabilize the climate, and maintain our standard of living all at the same time. It is well past time to start seriously harnessing solar energy.

Fossil-Fueled Problems

Before you read on, take a moment to look at the two corresponding pie charts comparing the earth’s estimated total reserves of nonrenewable energy resources with the annual renewable energy options. You’ll see that the potential of solar energy dwarfs all other options, renewable or otherwise. To understand why a solar electric economy is our best option, let’s look at the energy resources we currently depend on and compare them with the solar energy available to us.

To make things even worse, coal is very inefficient from a total energy perspective. It took billions of years of solar energy to form the coal we have today. And while coal is the most abundant fossil resource, the total amount of energy produced by burning all the coal on the planet would only be equal to the solar energy that strikes the earth in just six days.

Even if the problem of radioactive waste could be solved, the recoverable world reserve of fissionable uranium is equivalent to less than one and a half days’ worth of the energy striking the earth from the nuclear reaction of the sun.

Now consider that the entire recoverable world oil reserve is equivalent to the solar energy that strikes the earth in one day.

Biofuels and Hydrogen

Before we explore the solar electric future, let’s consider biofuels and hydrogen as other possible alternatives. Although both have received good press lately, neither is a viable solution for our future energy needs.

Waste oil and biomass can make good transition fuels, but unless human population growth slows, we will need all existing agricultural land to grow food. There are already many examples of food-producing cropland that is being converted to crops to make ethanol to power inefficient flex-fuel SUVs. The cost of tortillas quadrupled in Mexico in one year because of rising demand for corn to make ethanol. Why should the world’s poor struggle to afford food so the rich can greenwash their gas guzzlers?

According to some studies, it takes 1,000 gallons of water and more than a gallon equivalent of fossil fuel to produce 1 gallon of corn ethanol. And biofuels just aren’t very efficient. When you do the math, the overall efficiency of biomass used as transportation fuel, from sun to wheel, is about 0.01 to 0.05 percent. In contrast, the overall efficiency of using solar panels to charge electric vehicles from sun to wheel is 3 to 10 percent. This means that solar-charged electric vehicles are from sixty to one thousand times more efficient than vehicles burning ethanol or biodiesel. Food should always trump fuel.

Hydrogen fuel-cell vehicles are no more efficient than biofuels. Hydrogen is much lighter than air, and it must be contained in order to keep it from escaping the earth’s atmosphere, unless it is bound up in water or hydrocarbon molecules. The strong bonds that hold these molecules together take a significant amount of energy to break apart to extract hydrogen. Once the hydrogen is extracted, more energy is needed to compress it into a container that is small enough to store on a vehicle. In order for a fuel-cell vehicle to go 200 or 300 miles on a reasonably sized tank, the hydrogen must be stored in metal hydrates or at 10,000 psi in heavy containers.

Even after more than twenty years of development, fuel-cell vehicles still cost more than a million dollars each and don’t last very long or go very far. And finally, it takes about four times more renewable energy to drive a fuel-cell vehicle than it does to charge the batteries in an electric vehicle to go the same distance. This is like the difference in fuel economy between a Hummer and a Prius. If you are wondering why hydrogen fuel-cell vehicles continue to receive billions of dollars in funding given all these barriers, the fact that 97 percent of all hydrogen is currently extracted from fossil fuels may give you a clue. There are powerful vested interests controlling our energy policy. Only informed citizens acting together can steer the best course.

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Fig. 5.15. Montara Elementary School lunchroom with building-integrated photovoltaics (BIPV) on the metal roof.

A Bright Solar Electric Future

A solar electric economy is well within our reach. We’re already generating solar electricity at the utility scale using powerful concentrating solar power technology. We’re also generating electricity through wind energy, which is really an indirect form of solar energy because it’s driven by temperature differences created as the earth rotates and is exposed to heat from the sun.

Simply incorporating the energy efficiency, conservation, and solar design strategies in this book can save up to 95 percent of the energy that is used in conventional buildings. With the addition of building-integrated photovoltaics, buildings can be turned into net energy producers.

The cost of conventional crystalline PV modules dropped more than 25 percent in 2009, and new thin-film technologies are pushing the manufacturing cost even lower. Crystalline PV modules are made by encapsulating wafers of highly refined silicon under rectangular sheets of glass framed with aluminum extrusions. Crystalline PV has dominated the industry since the discovery that sunlight could be turned into electricity. For more than fifty years, incremental improvements in conversion efficiency and manufacturing competence have resulted in glass-covered aluminum-framed modules capable of converting 12 to 18 percent of the solar radiation that strikes them into electricity. Crystalline modules still dominate in PV sales, but in the last few years most of the new development work has been focused on thin-film PV technologies.

Large-area thin-film PV modules and laminates have been commercially available since the 1990s, and the products now on the market have conversion efficiencies of between 6 and 11 percent. The higher the efficiency, the less area and support structure is required to produce the same amount of electricity. But the cost of manufacturing some thin-film PV technologies is much lower, and some thin films have much better high-heat and low-light performance than crystalline PV cells.

In 2005, more than 95 percent of the PV market was served by crystalline modules. Since then there has been a steady rise in the market share of thin-film PV. Hundreds of thin-film PV companies have entered various stages of product development or production. For every thin-film company having some measure of success, there are a dozen or more that are struggling with lack of adequate funding, development delays, or cost overruns. The vast majority of these companies are encapsulating their thin-film cells under glass. The glass PV module market is almost entirely driven by installed cost, so there will ultimately only be a few low-cost survivors.

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Fig. 5.16. Photovoltaic systems integrated into roofs.

Four Semiconductor Materials Dominate the Thin-Film PV Industry

1. Amorphous silicon (a-Si), first developed in the 1970s by Stan Ovshinsky, the founder of Energy Conversion Devices (ECD), became the material of choice for charging consumer products such as watches and pocket calculators. ECD’s solar division, Uni-Solar MI, produces a-Si, flexible thin film with a real-life conversion efficiency of 8.5 percent and a maximum lab efficiency of 13 percent. They offer a twenty-five-year warranty on their laminates when they are bonded to specified roofing products like standing-seam metal or flexible-membrane roofing. Despite relatively low efficiency and high manufactured cost (around $2/W), the unique ability of their laminates to be adhered to roofing products has made Uni-Solar the undisputed leader in flexible thin film for more than a decade. This dominance will probably soon be challenged by manufacturers that use less expensive deposition and encapsulation techniques or develop products that do not require roofing as a substrate. There are many companies attempting to compete in the rigid PV module market with a-Si deposited on glass, but none will likely survive unless they can challenge the low cost records set by First Solar with CdTe (see below).

2. Copper indium gallium diselenide (CIGS) was developed in the 1980s as a high-efficiency (11 percent real life, 20 percent lab) alternative to a-Si. The fact that CIGS degrades rapidly in the presence of moisture has led several well-funded companies including MiaSolé, Nanosolar, and SoloPower, all of California, to encapsulate their flexible cells under glass. This method of encapsulation squanders the lightweight flexible advantage of thin film and puts these companies in direct competition with every other PV module manufacturer in a race based only on cost. Global Solar in Arizona, HelioVolt in Texas, and Ascent Solar in Colorado are the leaders in flexible encapsulation but do not yet have commercially available products. Solyndra is the only CIGS manufacture that has a product ready for the building industry. To solve the moisture-degradation problem, Solyndra deposits CIGS on the inside of small glass cylinders and hermetically seals the ends. They have developed a method of fast installation of their finished modules on large flat roofs that does not require the roof penetrations or the heavy ballast needed for the installation of most glass PV modules. If the moisture-degradation issue can be solved, CIGS, with the highest potential efficiency of any thin film, will probably be the flexible thin-film material of choice.

3. Cadmium telluride (CdTe) was developed in the 1990s and has a real-life efficiency of about 11 percent and a maximum lab efficiency of 16 percent. First Solar in Ohio has recently overcome concerns about the toxicity of cadmium and is now the low-cost leader for large-scale ground-mount installations. The Swiss Federal Laboratories for Materials Testing and Research in Dubendorf, Switzerland, announced in August 2009 that it has improved the efficiency of flexible CdTe thin-film solar cells to 12.4 percent. This development has the potential to make CdTe the low-cost leader for flexible thin-film applications.

4. Organic thin films currently are low efficiency (less than 6 percent) and have a short life expectancy (under six years), so they are far from having a viable product for the building industry or to compete in the PV module market. G24 Innovations, a manufacturer of dye-sensitized solar cells, made the first-ever commercial shipment of PV modules in October 2009 to Hong Kong for use on bags and backpacks. Konarka in Massachusetts, another organic thin-film manufacture, has purchased a Polaroid printing facility capable of producing 1 GW of flexible plastic PV per year. This manufacturing output is predicated on the company’s goal to raise efficiency to 10 percent and the life of its product to twenty years by 2011.

Utility-Scale Ground Mount

In 2009, First Solar was the undisputed leader in PV-module price reduction. They overcame concerns about the toxic cadmium used in their modules with a cradle-to-cradle recycling program and produced more than 1 GW (1 million kW) of cadmium telluride (CdTe) on glass modules with an average of 10.9 percent efficiency and excellent high-heat performance in 2009. First Solar’s revenues have grown from $14 million in 2004 to $2 billion in 2009 as they have lowered their manufactured cost from $3/W to $0.93/W. This is close to half the manufactured cost of crystalline modules and most other thin-film PV products on the market. They also dramatically reduced the balance of system (BOS) costs to $1.20/W. The BOS includes wiring, inverters, and mounting structures, essentially everything but the PV modules.

Their winning cost-cutting approach also includes reducing the permitting and installation time from years to months on utility-scale projects. Initial side-by-side comparisons done by Fat Spaniel show a 10 to 15 percent savings in installed cost with First Solar modules and about 10 percent greater output than crystalline modules with the same rated capacity. In August 2009, Southern California Edison signed a contract for 500 MW of First Solar modules for a desert installation capable of powering 170,000 homes. Then in September, First Solar announced plans for a 2 GW installation in China. By 2014, First Solar is committed to increasing the efficiency of their modules to 15 percent, decreasing their manufactured cost to $0.52/W, and decreasing their BOS cost to $0.95/W. If First Solar is successful in meeting these goals, sometime early in the next decade utility-scale thin-film PV will take a place alongside wind and concentrating solar power (CSP) to make the construction of new fossil or nuclear power plants a thing of the past.

A future with utility-scale solar power plants is a step in the right direction, but it still leaves control of power production in the hands of relatively few large corporate and municipal utilities. In addition, getting the power from areas that have the best solar resource, like the Southwest, to the heavily populated areas of the country that have less sunshine would require a vast new network of transmission and distribution lines along with a huge buffering infrastructure to store excess power when demand is low and release power when it is needed. The monetary and environmental cost of this scale of new infrastructure will be a significant obstacle to centralized power production.

Roof-Mount Distributed Generation

The alternative to centralized power production is distributed generation (DG). DG can make the existing grid operate more efficiently and limit the need for a huge expense in installing new transmission and buffering infrastructure by producing power where it is used. There is enough existing sunbathed roof and parking-lot area that could be covered with PV arrays to provide all the electricity used in buildings and to charge a national fleet of plug-in vehicles. The same mass adoption that made room-size mainframe computers give way to laptop PCs will make huge central power plants give way to rooftop PVs.

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Fig. 5.17. (a) DG on the Google headquarters. (b) DG on residential roofs in Japan.

Net Metering

Net-metering laws that allow the energy produced by residential and commercial PV installations to be fed into the grid are now in place in almost every state. Net metering is a win–win–win for the utility, building owners, and all life on the planet. The utility adds more clean power to its network from a power source located close to demand centers, reducing not only the need to build new plants to meet peak demands but also the load on distribution lines. The process is a win for the building owner, who doesn’t need a bank of batteries to store electricity to power the household at night or during overcast days. Instead the system uses the utility grid as a storage battery. And with every PV installation there are less CO2 emissions, and we all breathe a little easier.

Here’s how net metering works: When a solar electric rooftop produces more electricity than the household needs (at midday when the family is away at work and school), electricity is sent to the utility grid, and the home’s meter runs backward. When the household needs more electricity than the rooftop system produces (at night), it is drawn from the utility grid and the electrical meter runs forward. The net difference between electricity exported to the grid and grid electricity used forms the basis for the homeowner’s electric bill. In many states, net metering is annualized: The utility credits solar electricity produced by the rooftop system during the summer against electricity needed from the grid during the winter. Some states like California have Time of Use (TOU) net metering that allows PV owners to be compensated at a much higher summer afternoon rate when their array is at peak performance. It is time to make the advantages of net metering available to everyone with a national standard that would incorporate the best from the individual state programs.

Incentive Programs

Many states also have incentive programs for installing solar power and hot water, and there is currently a 30 percent federal tax credit to offset the cost of PV installations that will expire in 2016 unless it is renewed. There is a very helpful Web site (www.dsireusa.org) that lists all the incentives, programs, and laws that pertain to renewable energy in every part of the country. States such as New Jersey and Pennsylvania have programs that can make PV installations cash-positive from day one.

Not so long ago, the United States led the world in PV installations, but today places like Japan, Germany, and Spain are well ahead of the United States in installed capacity. Many countries in Europe have encouraged solar installations by offering low- or no-interest loan programs that can be paid off with premiums paid for electricity from clean renewable sources like the sun. These payments for energy produced from renewables, called feed-in tariffs (FITs), have been so successful that solar roofs are common in some countries. One in five roofs are covered with PV in the state of Bavaria, Germany, and 15 percent of Bavarians’ electricity comes from solar energy. By comparison, California, with over 60 percent of the PV installations in the United States, gets less than 1 percent of its electricity from the sun.

To date, most of the federal stimulus money earmarked for renewables, is going to utility-scale projects. It will take citizen action to convince Washington that these funds should be redirected to revolving low- or no-interest loans and FITs. These programs would cost the taxpayers less money and promote true solar independence.

Many of the countries that have used FITs to stimulate renewable-energy installations have acknowledged the benefits of DG by offering a higher payment for PV that is installed on buildings. Germany was the first to establish a FIT and started with a program that paid $0.74/kWh for electricity for DG installed on buildings and $0.52/kWh for electricity from ground-mount installations. Ontario, Canada, now has one of North America’s first FITs, which pays up to $0.80/kWh for roof-mount PV and only $0.44/kWh for PV mounted on the ground. France recently introduced a FIT that pays $0.38/kWh for ground mount and $0.57/kWh for PV mounted on commercial buildings. The higher payment for PV mounted on buildings is intended to help businesses, factories, and farmers take profitable advantage of their large rooftops. France also has a new category that pays $0.70/kWh for building-integrated photovoltaics (BIPV) to recognize and promote the synergies and cost savings available when PV materials are used to replace conventional building materials in parts of the building envelope such as the roofing, skylights, awnings, or facades. Finally, the advantages of using the sunbathed portions of a building’s skin to generate energy are starting to be understood and supported.

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Fig. 5.18. Habitat for Humanity/Uni-Solar project in Sacramento, California.

Building-Integrated Photovoltaics (BIPV)

The idea of BIPV is not new. Architects like Steven Strong and Richard Schoen have been using PV modules as roofing since the early 1980s, but using the glass modules that were available at that time was both challenging and expensive. Glass is transparent, weatherproof, and long lasting, but it can shatter, and it is not an ideal roofing material.

There are applications where glass PV modules can replace existing architectural elements such as awnings and facades. A few companies produce thin-film modules that can be used as windows with various degrees of transparency. These modules, like their crystalline cousins, come at a fairly high cost, but in urban areas at high latitudes the walls of multistory buildings receive more solar radiation than their roofs, so glass modules will continue to be used for a few applications. Having products for their high-end BIPV applications is important, but imagine the potential of being able to cover the solar-exposed surface of any building with low-cost roofing or siding that generates electricity at competitive costs.

Uni-Solar’s amorphous silicon (a-Si) thin-film laminates have been demonstrating the advantages of lightweight flexible solar cells on rooftop applications since 1997 with hundreds of megawatts of installations bonded to roofing substrates. In the late 1990s, Uni-Solar started the transition from framed modules to BIPV with flexible laminates bonded to metal roofing and strips of thin-film cells that mimicked asphalt shingles. Uni-Solar’s shingles were difficult to install and the traditional adhesives used in the PV industry were flammable, so the product never got into mass production and was eventually discontinued. In 2001, Southern California Roofing spun off Solar Integrated Technologies (SIT) and developed a process for bonding Uni-Solar laminates to membrane roofing. SIT became the first of many roofing companies to work with PV manufacturers to make products that serve the dual function of weather-tight surface and power generation.

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Fig. 5.19. A Solar Integrated Technologies project in Los Angeles, California.

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Fig. 5.20. SRS Energy’s Solé Power Tile, which incorporates Uni-Solar cells.

In January 2009, Carlisle Energy Services, a newly formed division of Carlisle Construction Materials, a leading manufacturer of energy-efficient single-ply commercial roofing systems, announced a multiyear agreement to purchase Uni-Solar laminates. In July 2009, Johns Manville, a leading global manufacturer of single-ply, built-up, and modified bitumen roofing-membrane systems, announced the formation of a new business entity called E3 Company and a multiyear agreement to purchase Uni-Solar laminates. In August 2009, Uni-Solar announced a merger with SIT and in October 2009, the merged company announced the sale of 4.8 MW of PV laminates to be installed on eight large commercial rooftops in Barcelona, Spain. Also in October, CertainTeed, a leading North American manufacturer of asphalt shingles, announced a joint agreement with Uni-Solar to develop roof-integrated PV products for the residential market. The New York Times ran an article in October 2009 on SRS Energy’s Solé Power Tile, which incorporates Uni-Solar cells into a curved Spanish tile roof.

In addition to alliances between roofing companies and PV manufacturers, major chemical companies such as BASF, DuPont, 3M, and Dow have all formed solar divisions to improve the transparency, durability, and fire resistance of the materials used to encapsulate PV cells. In September 2009, Dow Building Solutions announced that they are working with Global Solar, a leading manufacturer of CIGS flexible thin-film cells, to develop 15.5 percent efficient solar roofing shingles.

Electric Vehicles and Plug-In Hybrids

The other development that will bring solar energy to the mainstream is the plug-in vehicles that are now available on showroom floors. Given the choice between paying 10 cents or more a mile for fuel in a polluting, fossil-fuel combustion car and 1 to 3 cents to go the same distance in a clean EV, people should promptly start adopting plug-ins and plug-in hybrids. BIPV installations will follow as a popular way to achieve energy independence and to provide clean electricity for battery charging.

Most people don’t realize how much energy they use in their cars. A gallon of gasoline is 30 kWh of concentrated solar energy that was hundreds of millions of years in the making. About 30 kWh is consumed each day in the average US home. So if you burn more than a gallon of gasoline a day, you could be using more energy in your car than you are in your home.

Fortunately, electric-vehicle drivetrains are inherently five to ten times more efficient than internal combustion engines, so switching to EVs will require far less energy than fossil-fueled transportation. Even if the electricity to power EVs comes from fossil-fueled power plants, emissions are much lower per mile traveled than with internal combustion engines, and they produce no greenhouse gases at the tailpipe. In addition, electric vehicles can be charged directly from renewable sources, eliminating emissions altogether.

One of the main excuses the auto industry offers for the lack of electric vehicles is that “the batteries are not developed yet.” But consider how quickly cell phone batteries developed, transforming mobile phones from heavy, bulky, short-lived nuisances to amazingly light, small, and long-lasting necessities. The oil companies are doing a good job of protecting the American consumer from “dangerous” batteries, but in parts of the world where oil companies have less control, large-format battery development is progressing very rapidly. The collapse of the American auto companies is at least partially the result of the petroleum industry’s ability to stifle clean technology development. As affordable EVs come on the market, despite Big Oil’s best efforts, and word gets out that you can do your commute with the same comfort and convenience for 2 cents a mile instead of 10 cents, even billions of dollars in advertising won’t stop the revolution. Don’t wait, or you’ll be on a waiting list. Electric scooters and trucks are also on the way. China now has 120 million electric scooters in use. Urban trucks and transfer vehicles are well suited for electric power, with clean, low-cost, and high-torque motors well suited for short trips. Flywheels may also prove valuable in some applications.

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Fig. 5.21. Toyota RAV4 EV and solar-charging shed on the Heckeroth Homestead, Albion, California.

Agriculture and Electric Tractors

Experts have estimated that it takes eight to ten units of fossil energy to put one unit of food energy on American tables, and that it takes the annual equivalent of 10 barrels of oil to feed each person in the United States. It is frightening to imagine what will happen as oil supplies dwindle and prices rise. Farm machinery, like almost all modes of transportation, is totally dependent on oil.

The good news is that not only can tractors run on electricity, they make even more sense than other EVs because they can use battery weight for increased traction, and they operate at slower speeds. A solar-charged electric tractor can quietly accomplish all the tasks necessary to maintain productivity on a farm.

Dealing with the rising cost of mobility and energy are huge challenges, but the biggest challenge facing humanity may be maintaining an affordable and nourishing food supply. We can have fresher and more nourishing food without fossil fuels. What it will take is public support for a switch to local food production on small organic farms using solar irrigation pumps and solar-charged electric tractors.

We Have the Power

It’s easy to feel confused, cynical, and even hopeless about the state of the planet these days. But we are excited and optimistic because we know the technology now exists that will allow us to wean ourselves from fossil fuels and move to a renewable solar electric energy system.

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Fig. 5.22. SolTrac and solar-charging shed on the Heckeroth Homestead.

Yes, solar panels are still too expensive for many. But ten years ago, nobody gave hybrid cars a chance of succeeding. Today, the Toyota Prius is the hottest thing going. Plug-in hybrids and a wide range of all-electric options are now available. For every new development that has been announced in the press, there are dozens more in the works that will make future generations wonder why people ever burned fossil fuels to make energy.

If we work together and demand that our government set a wise energy policy and use taxes to support the right renewable energy options, we can put the brakes on climate change and enjoy clean, truly green energy sources and a healthy planet.

Your Solar Electric System

The design and detailing of a solar electric system is not difficult, but it is important to get it right for safety and performance. Working with an experienced contractor is often a good idea. The general steps include:

1. Minimizing energy demand. It is cheaper to conserve than to generate electricity. Smaller, more efficient appliances and minimal parasitic losses are essential to reduce demand. Develop a load profile of your current use as a starter, then rethink and revise to fit a solar electric lifestyle. This is less important if you are doing a grid-tied system—but essential for a stand-alone system. Time for that Sun Frost refrigerator! Many off-grid rural residents do just fine with a 1 kW PV array that might produce only 5kWh a day (one-quarter to one-tenth the energy use in many new homes).

2. Understanding sun availability and microclimate. When and where does the sun reach your home or site? Solar-site evaluation is not difficult once you understand the sun paths through the year. A solar-site selector or other tool can help. Full sun is best, but partial shading can be managed by choosing a more flexible inverter or different wiring configuration. Roof, ground, and, more rarely, wall mounting may make sense. Understanding the site microclimate, wind speeds, snow loads, highest and lowest temperatures, frequency of lightning strikes, cloudiness, and sun availability can help guide the design process. Could you add microhydro or wind? For more details on step 1 and 2, see “Getting Started with Renewable Energy: Professional Load Analysis and Site Survey” from Home Power magazine, www.homepower.com/webextras.

3. Developing, with this information, a plan for your home solar electric system. Will it be stand-alone, grid-tied, or grid-tied with batteries? Will it be minimalist ($3,000) or full capability ($30,000)? Stand-alone usually makes sense primarily where the building is far from a power line and where power line installation costs would equal or exceed the cost of a solar system. What kind of PV panels will be used? Tracking or fixed? Thin film on metal roofing, crystalline glass, or some other option? Will the system be 12, 24, or 48 volts? Wire size? Battery bank size? AC or DC? Inverters? Controllers? Monitoring system? Lightning protection?

4. Doing a full economic analysis and exploring the availability of rebates and incentives comes next. Can you afford the system? What is the current cost? Maintenance cost? Future cost? What are the steps to qualify for rebates?

5. Determining whether you will be self-installing, hiring a contractor, or working with a contractor. What are the code requirements, incentive requirements (some require certified systems), skill and time constraints? Make sure all information needed for incentives is collected and maintained. Pull permits, construct, manage inspections, and complete.

6. Testing and refining the operation of the system. Some tuning is often needed to improve efficiency and performance.

7. Enjoying, monitoring, and maintaining your energy independence.

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Fig. 5.23. Electricity consumption analysis for on-site generation with rooftop PVs.

Rainwater and Water-Use Management for Low-Impact Development

Low-impact development (LID) is characterized by having a high percentage of pervious surfaces; regenerative, native, or edible landscaping; water filtration and filtration of on-site pollutants; and surface drainage that recharges the local aquifer or is harvested for use.

fig.5.24b.ai fig.5.24a.tif

Fig. 5.24. Low-impact development.

High-impact development (HID) is characterized by having high percentages of impervious surfaces, landscaping that is mostly decorative, stormwater issues and pollution that have typically been handled by concrete curbs, pipes, and canals.

Rainwater Harvesting and Use

Rainwater or snowfall is often an important on-site resource. Ideally a building and site will be designed to live with the precipitation that falls on-site—without imports. Building and site-design choices determine how efficiently these resources are captured for use. Water may be captured and stored for landscaping use by site-development choices, or captured for use in the home or garden from the built surfaces. This salt-free and generally fairly pure water is a tremendous resource that is often neglected and wasted. Capturing rainwater for use on-site reduces the adverse impact of impervious surfaces on stormwater runoff and flooding.

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Fig. 5.25. High-impact development.

Materials don’t matter much if the water is intended for landscaping use, but if water is collected for drinking, the choice of catchment materials is important. Some cities and counties, like Tucson and Santa Fe, now require rainwater collection for some types of development. Texas was the first state in the United States to embrace rainwater harvesting, but Hawaii, North Carolina, and many other states are now catching up. North Carolina and the Florida Keys now have rebate programs. Parts of Australia have relied on rainwater harvesting for many decades, and many building codes now require catchment and storage systems, with tanks up to 800 gallons required on the Gold Coast. Europe and the UK have also become much more interested in rainwater harvesting after recent droughts. Rebates or tax credits are being offered in more areas every year. As interest grows, contractors emerge to provide turnkey rainwater harvesting solutions. Communities that charge a stormwater runoff fee can also encourage rainwater harvesting if the runoff reduction is recognized in lower fees. Sadly, in many areas of the United States and other developed countries, building officials may obstruct use of this important resource; the stormwater problem is rarely seen as a rainwater harvesting opportunity, and in some areas rainwater harvesting has been deemed illegal.

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Fig. 5.26. San Luis Obispo Botanical Garden Education Center fosters water consciousness and reuse.

Landscape Design for Rainwater Capture

Landscape design for rainwater capture and use can include use of permeable (pervious) pavement or cement for driveways, patios, and sidewalks, living roofs, and ground shaping to hold rainwater so it can infiltrate into the soil. Permeable pavements are made by reducing the amount of fine material in the mix of concrete or asphalt. Once contractors become familiar with the process, the costs are comparable. In Europe, these materials are sometimes used even on freeways and major highways. Rectangular stone paving (setts), pavers, and bricks with porous fill in the spaces between pieces can also help retain and capture rainwater.

Rainwater capture on the development or city scale is often more effective using aboveground drainage systems. Swales, berms, check dams, infiltration basins, and depressions can be used to slow or capture runoff. Gravel infiltration beds under parking lots or impermeable surfaces can also be created. Streets, sidewalks, and natural rock outcrops can also be used to collect and channel water to landscaping areas. Landscaping plant choices can also improve rainwater capture and use. These natural rainwater management approaches are typically less costly than stormwater pipe systems and should be a first priority in drier areas where water is in short supply. A living roof can be used to capture and hold rainwater on a building’s roof.

Buildings

Building design for rainwater capture and use typically includes a catchment area (usually the roof), conveyance systems (gutters, downspouts, and piping), possibly a filter or two, storage (tanks or cisterns), and some method for redistributing the water for use. The best roof materials are coated steel or aluminum (to reduce zinc or aluminum leaching), slate, clay, or cement tile, or other durable materials. Asphalt shingles are less than ideal, as they can contribute grit and chemical compounds to the system, but they have been used. Copper and lead flashing should be eliminated to reduce leaching. Catchments of metal roofing material or concrete can also be created specifically to capture water.

Rainwater Collection

Gutters are commonly used to collect water from the roof. Gutters must be sloped for good drainage (often suggested as minimum 1/16-inch drop per foot of run). Gutters should be well mounted and durable. Gutter screens can help keep debris out of the water.

fig.5.27a_alt1.tif fig.5.27b_alt1.tif

Fig. 5.27. Rainwater harvesting, Village Homes in Davis, California. The city resisted aboveground drainage—but was finally convinced to try it. After the first flooding rainfall, only Village Homes experienced no problems and the city revised its policies.

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Fig. 5.28. Rainwater harvesting, Australia.

Downspouts should be sized for typical rain intensity, often 1 square inch of downspout opening for every 100 square feet of roof area. Rough filtering can be done at the gutter-to-pipe transition with a sloped screen. The WISY company in Germany has developed a clever filtering system for rainwater using a fine-mesh filter that is widely used in Europe.

First-flush filtering is desirable to eliminate dirt, bird droppings, and other deposition on the roof. A wide range of first-flush filters have been developed. One common type runs water into a chamber that must fill before the water can run into the cistern or tank. In some cases a floating ball rises and seals the chamber so the water from the now clean roof runs by. The first-flush chamber usually has a slow drip or outlet so that it will be empty by the time of the next rainfall. A manual switch can be used in areas with pronounced seasonal rainfall. The first rainfall of the season might all be diverted to wash off months of dust and deposits.

Pipe Runs

Pipe runs to the tank or cistern should be sloped sufficiently and run without complex turns or drops that can lead to clogs. Use large pipe diameters to reduce overflow and blockage. Provide cleanouts as needed. Screen or mesh should be in place to prevent mosquitoes from breeding in pipes or tanks. A variety of system configurations can be used to suit aboveground or belowground storage and pressurization needs. An aboveground tank can be more challenging to reach from gutters and may lead to a collector pipe array that is not attractive. A belowground tank is easier to fill from a buried collector system and more attractive, but it’s harder to clean and repair. A larger home might have a belowground tank in front, and an aboveground tank in the back or a side yard. A belowground tank can be pumped through a filter system up to a use tank to provide a gravity head.

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Fig. 5.29. (a) First-flush filtering. (b) Metal cap serves as first-flush diverter (seasonal). (c) Ball-valve diverter. (d) Commercial filter system.

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Fig. 5.30. Storage tanks in Sweden, Australia, and the UK.

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Fig. 5.31. Access hatch. A childproof lock should be installed.

The storage tank or cistern is sized to fit the rainfall and use patterns. Tanks can be located above- or belowground, made of concrete, steel, polypropylene, food-grade polyethylene, or other materials. They can be incorporated in the house as thermal mass, or installed in an insulated shelter and used as a heating or cooling source. A cistern or tank can be installed in the backyard or under a patio or courtyard. In a retrofit situation, a small swimming pool can be converted into a cistern by adding an appropriate cover.

Storage should be durable and watertight with a clean, smooth interior surface. It should be fully accessible through a manhole for cleaning and silt removal. The cistern should be covered to keep children and critters out and prevent mosquito breeding and algal growth. A lock should be installed to keep children out. Two or more cisterns can be used to improve water quality and to allow servicing one of the units without losing the operation of the system.

Water Terms

Maintenance

A rainwater system requires maintenance and care. It is a living system, and to operate efficiently, it needs to be cleaned and cared for properly. The gutters will need to be cleaned, roughing filters will need to be cleaned, and silt may need to be removed from the cistern periodically. Careful maintenance is particularly important if rainwater will be used for drinking water. Approved water-quality testing may be required for home systems that use the water for drinking water, and will almost certainly be required for community systems.

Cistern Sizing

Storage sizing depends on the patterns of use and rainfall. The more even the rainfall pattern is, the smaller the tanks can be, particularly if use is regular as well. Storage for just a couple of weeks of use may be sufficient if it rains almost every day (1,000 gallons). A 4-foot-deep cistern built under a 200-square-foot patio will hold about 6,000 gallons.

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Fig. 5.32. Rainfall-harvesting estimation by plotting use and collection.

Table 5.1. Water use in the home and outside varies widely locally and globally. Understanding water resources and uses is necessary for designing a sustainable water supply system that may entail rainwater, gray-water, and perhaps black-water use.

t0501.eps

In areas with strong seasonal rainfall patterns (dry winter or dry summer) and recurrent droughts, bigger tanks are needed. In San Diego, some early homes had 35,000 gallons of storage. For more detailed procedures on estimating size, see Gould and Nissen-Petersen (2003*).

You can estimate the potential for rainfall harvesting and the cistern size needed by plotting average likely rainfall harvest per month and contrasting this with water demand. figure 5.32 shows a strong seasonal rainfall pattern. A large cistern would be needed to carry this house through the dry months and a drier-than-average year. For a home with a 1,200-square-foot roof, the 5-gallon-per-square-foot deficit would suggest at least a 6,000-gallon tank, but a tank twice as large would be even better to allow for a drier-than-average year.

Gray-Water Harvesting and Use

Following the material flows through a house or building offers many opportunities for turning perceived wastes into resources. Water that has been made dirty or “gray” by use in a sink, shower, or laundry is a good example. Reuse of some types of gray water is technically simple, but may be restricted by public policy. The types of gray water produced by a building include a wide range of physical, chemical, and biological loading—as we can imagine by comparing the shower, sink, and laundry water of a retired couple that buys only “organic and readily biodegradable soaps and cleaners” with a young family with three children in cloth diapers and little time, money, or inclination to seek out safe cleaners and soaps. These differences contribute to the regulatory pressure from health departments for “Cadillac systems,” but growing water shortages and improved understanding of the best gray-water practices are encouraging many jurisdictions and states to encourage gray-water use and to support personal initiatives to reduce environmental impacts of living.

The water flows out of a home include clean water, gray water, black water, and yellow water. Clean water and gray water will be discussed in this section.

Clean Water

Water run while warming water for a shower or cleaning dishes, drip from a refrigerator compressor, and reverse-osmosis drain water is often completely clean. This should be captured for reuse in toilet flushing or landscaping. Return pipe systems are available to avoid losing water during warm-up. Hot-water recirculation systems are popular for delivering hot water in a timely and water-conserving fashion, but they do require a pump and additional energy to recirculate the water. Locating the water heater near major uses can reduce water waste.

Gray Water

Gray water may be used for landscape irrigation and toilet flushing depending on local regulations. Some areas will even allow kitchen-sink water to feed into the gray-water system, but this usually only occurs when there is treatment of the gray water before it is reused or sent into irrigation pipes.

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Fig. 5.33. The gray-water system illustrated here uses a pump, holding tank, and filtration to reuse large quantities of gray water for toilet flushing. Excess gray water must be able to be directed to the septic or sewer system via a bypass valve. Plumbers are usually able to deal with gray-water plumbing inside a building, and landscape installers are able to distribute the gray water into the landscape.

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Fig. 5.34. Available in Japan are dual flush, gray-water-integrated toilets that provide water for hand washing via a faucet and washbasin. Rinse water then fills the toilet tank and is used for the next flush. Dual plumbing is not required for this integrated system.

Gray water has been integrated into some innovative toilets that utilize a faucet and washbasin on the top of the toilet’s holding tank. When the toilet is flushed, the water used to refill the tank prior to the next flush is directed through the faucet for hand washing, then it drains via the washbasin into the toilet’s holding tank. This type of integrated gray-water system is popular in Japan and is one of the only systems that does not require dual plumbing.

Water from a washing machine using minimal amounts of a safe detergent to clean lightly soiled clothes is relatively clean in the wash cycle and even cleaner in the rinse cycle. My parents used this water for landscape watering for more than fifty years without a problem. Water from a shower or bath can also be fairly clean if safe soaps and shampoos are used. A pre-wash, following Japanese practice before entering the furo, would further reduce loading in the water. However, when users are sick, the load of viruses, bacteria, or parasites may increase.

If gray water is used for irrigation, it should be distributed subsurface and not sprayed overhead. It is also not recommended for use on certain edible plants, but this will vary depending on local code and risk factors.

Health Risks and Challenges from Gray-Water Use

Gray water is typically not regulated by the building, water, or stormwater departments, but by the health department. The health department is generally not interested in the problem of water supply or cost, but narrowly focused on eliminating or reducing the risk of disease. The health risks of using gray water are minimal—this is, after all, the water you just bathed in, or the residue from clothes you were wearing. A recent study of simple gray-water reuse systems in Jordan found no increase in infection.

There is no question that gray water can end up containing some infectious organisms, but so can city drinking water systems (David’s parents both got giardiasis from their city water system) and rainwater harvesting systems. It is possible to virtually eliminate pathways for infecting people from gray water by preventing human contact with gray water before purification and purifying gray water with healthy topsoil or other treatments.

If a flush toilet is required by law, it may be possible to use gray water for the toilet (some areas allow it; most do not at the moment). Gray water is best suited for subsurface irrigation of nonedible landscape plants or trees and shrubs where fruit will never contact the soil surface. Gray water can play a major role in watering landscapes even in very arid environments if salt, chloride, and boron levels in source water are not too high. Harvested rainwater can be used to dilute gray-water salt concentrations.

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Fig. 5.35. Energy intensity of water sources in San Diego, California. Source: Pacific Institute, Wolff et al., 2004.*

The amount of gray, black, and clean water a house will produce will depend on the occupants, their behavior, and the design of the house or building. The demand will also depend on the landscaping and gardening choices made. Average uses within a home vary nationally, regionally, and locally depending on the price of water, the attitude of the occupants, and the style of development. Note: figure 5.36 and table 5.2 neglect the clean-water flow that can be significant (perhaps 5 percent) with home designs where the point of hot-water use is a long way from the water heater.

A single-family household in Southern California coastal areas uses 38 percent of its total water budget outside, but in desert cities and neighborhoods with larger lots this can rise to 80 percent or more. Multifamily units have less outside landscaping, and use drops to 20 percent or less. Institution and commercial use is extremely variable.

Advantages of Gray-Water Use

The most obvious advantage of domestic gray-water use is that it replaces cleaner potable water that may have been shipped hundreds of miles at a very high economic and ecological cost. In places like San Diego, water from reclamation has the lowest energy cost, see figure 5.35. By storing winter gray water for use during the hot-dry summer months, sufficient gray water was captured to meet the full Casa del Agua landscape irrigation demand. Cohen (2009*) suggests that a simpler system using light gray water (Tiers 1 and 2, see table 5.2) could meet about 84 percent of outdoor residential water use without the need for treatment under current California regulations. Recycling all Tier 1 and 2 gray water would be sufficient to meet the full demand of outdoor water use in coastal Southern California.

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Fig. 5.36.

Table 5.2. How big is the resource?

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Adding heavy gray water would meet up to 41 percent of toilet-water use, provided this heavy gray water undergoes treatment before use. The estimated residential per-capita potable-water savings range from 16 to 40 percent for Tiers 1–3. It works at the scale of a home, but what if more homes got involved? With a participation rate of only 10 percent, the potable-water savings for the South Coast Hydrologic Region would range from about 40 to 100 million gallons per day (Cohen, 2009). This is equivalent to a modern large seawater desalination plant now proposed for California at cost of several hundred million dollars plus the ongoing energy cost of operation. The reuse of gray water at the point of use has the advantage of much lower cost and environmental impact.

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Fig. 5.37. Five typical gray-water system components.

With water costs rising, water, even gray water, will be considered a resource of greater value. This is leading homeowners and policy makers to view gray water as a valuable domestic water resource.

Gray-Water Systems

Typical gray-water systems include a collection system, surge capacity, filtration, a distribution system, and an end use. Storing large quantities of gray water is not recommended because it can turn into black water if it is not treated before storage. Treatment can take the form of sand filters, or chemical, UV, or ozone disinfection for gray water that will be held for toilet flushing.

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Fig. 5.38. Distribution options for landscape irrigation with gray water.

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Fig. 5.39. A few landscape irrigation distribution options are detailed below, but each site is different, and designing the right system for your site will be based on local codes, soils, et cetera. (a) Surge tanks. (b) Mini leach field. (c) Vegetated leach field. (d) Tree watering moat. (e) Reed beds.

The development of a gray-water system depends on the home or building, occupant, use, and goals. These installations range from very simple low-cost systems to highly complex and costly systems. A simple diversion pipe for the laundry might cost less than $10. A bucket to catch the clean water as the shower heats up may cost only $5. A gray-water use system designed to recycle washing-machine rinse water back into the washer for use in the wash cycle of the next load will cost more, but is easily constructed using a 32-gallon trash container placed adjacent to the washing machine, at a slight elevation. After the wash cycle has drained, the drain hose from the washing machine is removed from the sewer standpipe and positioned to drain the rinse water into the container. The rinse water later is run back into the washing machine for use in the next wash cycle.

Often a valve-and-drain system can be added to make it possible to divert gray water for reuse, but to return flows to the sewer or septic system if there is a backup or surface flow. More sophisticated gray-water retrofit systems with settling tanks, pumps, controls, filters, and treatment devices can cost several thousand dollars. Designing gray-water plumbing systems for new homes is easier and reduces the cost. Even if a gray-water system is not installed, the stub outs and layout of the pipes can be made in a manner that facilitates retrofitting.

The system installed at Casa del Agua in Tucson is fairly simple. It drains gray water from the household’s water-using appliances into a 55-gallon sump surge tank with a filter fitted over the gray-water drain to remove lint and hair before the water is pumped to other components of the recycling system. As the sump fills, it activates a float switch and then pumps gray water into various treatment systems. The gray water is then pumped through an underground drip irrigation system to the landscape or for use in the toilet. The cost was about $1,500 (Gelt, 2009*). The gray-water storage tanks hold winter flows for use in the summer. Municipal water use was reduced 47 percent; gray water met 20 percent of total demand, rainwater 10 percent (Karpiscak et al., 2001*).

Rules and Regulations

The various states and counties can develop more sustainable water programs by increasing gray-water recycling as Australia has done. This effort will require public education and participation, certified and properly managed distributed gray-water recycling systems, centralized recycling plants where applicable, and incentives for gray-water recycling efforts.

Arizona has an approach that seems to work, based on size. Systems for less than 400 gallons per day that meet a list of reasonable requirements (thirteen best management practices, or BMPs) are covered under a general permit without the builder having to apply for anything. With this one stroke, Arizona has raised its compliance rate from near zero to perhaps 50 percent. Homeowners are more likely to work toward compliance for the informal systems that still fall short of current requirements. This simple code also opens the door for professionals to install simple and cost-effective systems. Systems that process more than 400 gallons a day or don’t meet the list of requirements, as well as commercial, multifamily, and institutional systems, require a standard permit. Systems that are larger than 3,000 gallons a day are considered on an individual basis. The Arizona law does not prescribe design specifics but requires that systems meet performance goals. This creates a favorable climate for innovation while technical progress is likely to eclipse prescriptive laws—but the manual and BMPs can easily be updated because they deal with performance.

Black Water, Dark Gray Water, Yellow Water

Your shit is gold.

—F. Hundertwasser, 1976

What is normally demeaned as human waste is usually transported by water that is then demeaned by calling it black water. One of the strangest things our society does is transport water hundreds of miles, clean it at great cost, then contaminate it in a toilet and ship it again for high-cost treatment. This is expensive not only in terms of water but in terms of energy and the loss of a valuable agricultural resource. It is estimated that 20 percent of the energy used in California is used for pumping water.

Besides using valuable water and expensive energy, the infrastructure involved has become very expensive. The federal government no longer pays such a large percent of sewer and water treatment plant costs, and the hidden subsidies have declined. As a result, water scarcity and sewer system expenses have begun to limit growth.

A case in point is Los Osos, California, a moderate-income community on the coast, under a twenty-five-year-old building moratorium resulting from the failure to build a traditional sewer system. This would be so expensive to homeowners that many on fixed incomes would probably have to leave. The politics of this situation has been very intense and divisive to the whole community. Los Osos is just the harbinger of things to come for many communities as high energy cost and water shortages are exacerbated by rising sea levels, drought, and erratic weather from global warming.

Black Water

Black water can be treated at the home or building scale with a biological treatment system (just as nature does it); but this treatment is more complex, requires more care, and is likely to be resisted by building and health authorities. Reed beds and engineered wetlands have been developed and successfully operated at the home and building level and will one day be common, but are best at the neighborhood scale.

Composting and other waterless toilets are another alternative but can pose a challenge in retrofits. It’s best to plan for them before construction. These cost less than adding equal capacity to a sewer system and treatment plant. Regulatory conditions are also a factor. Many state and national parks use waterless toilet systems, and composting toilets are legal in some areas like the state of Arizona.

Dark Gray and Medium Gray Water

Dark gray laundry water from washing a big load of dirty diapers can be close to black water.Water from a kitchen sink with a heavily used garbage grinder or disposal unit can be fairly rich in biological material and might be called medium gray. It’s better to have a compost or vermicompost (worm bin) for kitchen scraps so that sink water can be used in a gray-water system as discussed in Gray-Water Systems.

Yellow Water

Water from a toilet flushed with just urine is relatively safe. The challenge is separating it, perhaps with a urinal for men. A more complex arrangement of an in-toilet urine diverter has been developed for women—but would face strict health-code scrutiny.

Urine is close to sterile as it leaves the kidneys but may be contaminated on the way out of the body. The Inuit used to use urine to brush their teeth, and soldiers are advised to use urine to clean wounds if no water is available. A waterless urinal can be installed in a home or commercial or industrial space. These are good for water conservation, but not so good for resource recovery.

Urine as a resource is beginning to gather attention because of the looming phosphorus and fixed-nitrogen crisis mentioned seen in figure 5.2. As time goes by, perhaps the term for urine will progress to yellow water and then to gold water.

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Fig. 5.40. (a) Conventional wastewater treatment plant, San Luis Obispo, California. (b) Diagram of the wastewater treatment process.

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Fig. 5.41. C. K. Choi Building, University of British Columbia, incorporates composting toilets. (a) Exterior of building. (b) Maintenance chamber. (c) Diagram of Clivus Multrum composting toilet.

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Fig. 5.42. (a) Arcata, California, constructed wetlands waste-treatment facility. Photo: Poppendieck. (b) Diagram of wastewater treatment process.

Good-Bye to Black Water, Hello Gold Water!

Waterless toilets are readily available and can be installed in many situations without a great deal of difficulty. In rural areas a simple pit privy or long-fall toilet may suffice. Composting toilets of many kinds are sold and approvable in most jurisdictions, but if you are the first in your area, be patient. An electric-assisted compost toilet can be used even in retrofits with restricted space, but adds a global warming burden. A solar-assisted composter might be the best solution in many homes.

Composting toilets have been used on multifamily and commercial buildings in Europe. In Canada, there are five Clivus Multrum Model M28 composters at the C. K. Choi Building at the University of British Columbia. These serve ten flushless toilets and several flushless, trapless ventilated urinals. Each of these Clivus composters has an annual user capacity rated at 45,000 visits with a total annual capacity of 225,000 visits for the building.

fig.5.43a.tif fig.5.43b.ai

Fig. 5.43. Urine is valuable. Once separated, a passive building can be thought of as a collector of urine as well as sunlight. Residents of a housing project in Sweden and Svanholm Gods collective and organic farm in Denmark are recovering nutrients in this way. (a) NoMix, “the bowl of the future,” © 2007. (b) Diagram of wastewater process for a urine-separating toilet.

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Fig. 5.44. Converting and replacing existing systems. (a) The Los Osos, California, sewer would cost $12,333 per property. (b) A Los Osos composting toilet would cost $1,000 per property.

Green Materials

Sustainable buildings should be built with materials that are readily available, inexpensive, renewable, enhance biodiversity, resilient, with local control (to harvest or collect, build, maintain, fix, dispose of safely), community building, efficient of energy and resources, soft, safe, fun, healthful, asset building, equitable, pleasing, and empowering. They should improve access to healthful housing, improve quality of life, and increase ownership, and at the end of use they should be easily dismantled, separated, and returned to nature or returned to the eco-industrial cycle. The pueblos of the Southwest, the oldest occupied buildings in North America, are a good example. They are simply made of earth, wood, and stone. If abandoned, they would gradually return to the earth.

To understand the sustainability of materials, we need to consider their life cycle from their creation to their death or recovery. We should also consider the rarer, but still common events of buildings—flood, fire, and earthquake.

Material Life Cycles

Collection, transportation

Processing, transportation

Manufacturing elements and components

Transportation to site

Site erection and construction

Maintenance

Repairs

Refurbishment/remodeling

Demolition or dismantling of the structure at the end of its life

Transportation

Processing required for reuse, recycling, return to nature or disposal

How do the building materials respond? These can become the basis of the cradle-to-cradle life-cycle design described on pages 208 and 211.

Most analyses of building materials have neglected several of these steps. Sadly, the interesting and important challenge of developing more sustainable building materials has largely been ignored. The focus has typically been placed on low first cost, without considering life-cycle value, end-of-life issues, and external costs and risks. Material choices are complicated by larger systemic problems, including centuries of unsustainable forest management that have led to the growing use of less durable materials such as oriented strand board (OSB) in place of solid wood or plywood.

In the US construction industry, the materials choices and finishes have often become cheaper and less durable to reduce first costs. Even expensive homes often emphasize high-cost finishes such as granite countertops, while neglecting quality and longevity of basic home components and building materials. The failure of thousands of expensive homes with high-sulfur Chinese drywall is a perfect example. Seven million sheets of drywall were imported during a drywall shortage, and the high sulfur content has led to health and electrical problems. Although only a few thousand complaints had been registered with the Consumer Product Safety Commission as of 2009, as many as sixty thousand homes may be involved.

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Fig. 5.45. Six steps of life-cycle balancing. Source: Center for Maximum Potential Building Systems.

Building size and related ecological impacts are often neglected in green building magazines. A 5,000-square-foot home for a childless couple is not very sustainable, even if it has a high-efficiency furnace and energy-conserving high-quality windows. Green materials can be used to build a very inefficient building if sustainable design principles are ignored.

Green building has often focused rather narrowly on energy, and more recently on carbon footprint—rather than looking at the broader picture of sustainability and ecological and health effects. Plastic insulating foams, for example, are very good for improving thermal performance and structural integrity, but are virtually unrecyclable and make dismantling a structure very difficult.

A More Sustainable Approach

It doesn’t have to be this way. We can find many marvelous examples of local, site-adapted building technology from almost every country, climate, and region—yet they are often little studied and little known. Many superb books can introduce you to sustainable traditional designs, including Japan’s Folk Architecture; Just Enough; Architecture Without Architects; Architecture for the Poor; Built by Hand; Spectacular Vernacular; and Traditional Buildings, to list just a few (see references and further reading for more suggestions).

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Fig. 5.46. This birch-bark and green roof building in Sweden has been used for six hundred years.

Many traditional designs were limited by understanding of engineering and energy principles. This led to reduced performance at climate extremes and high risk during earthquakes. Sadly, despite new understanding and new materials, risk has remained high in many areas as concrete slab or block buildings with inadequate reinforcing or poor build quality have replaced equally dangerous stone or earth homes. More needs to be done to explore and improve the sustainability of traditional materials and to develop new building systems that take advantage of modern, but still sustainable, building materials that offer improved performance and safety. These include such things as straw bale building, flax insulation (now available in Europe), and straw panels. To choose green materials, we need to know their impacts, life cycle, and toxicity. Ideally they will be local and renewable, recyclable at the end of life, and safe for people and the environment.

Material Impacts

Peter van Dresser addressed the sustainability issue well in Home Grown Sundwellings, emphasizing the use of locally available materials even when performance would not be as good as the best available nonlocal alternatives. The straw bale building movement has stimulated discussion of many of these questions, but more detailed life-cycle cost analysis remains to be done. The comparison of materials can benefit from the careful use of the materials’ comparison technique developed by “Bio” Schmidt Bleek* and colleagues at the Wuppertal Institute in Germany. Their rating system for material (including energy) intensity per unit service (MIPS) is a useful method for estimating the ecological stress potential of materials, goods, and services.

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Fig. 5.47. Mud, stone, and wood, Taos Pueblo is one of the oldest continuously occupied buildings in the United States.

MIPS is the “ecological rucksack” or ecological footprint of materials, including abiotic and biotic material costs, air, water, land, and energy. MIPS is computed in material input per total unit of services delivered by the material or product over its entire useful life span (resource extraction, manufacturing, transport, packaging, operating, reuse recycling, and remanufacturing are accounted for, and so is final waste disposal). MIPS can help us account for the sustainability of materials at local, regional, national, and global levels.

Industrial products typically carry nonrenewable ecological footprints about thirty times their own weight. This means that less than 5 percent of the nonrenewable natural material disturbed in the ecosphere ends up in a technically useful form. For electronics it is worse, with ecological footprints of a personal computer often two hundred times their weight.

Table 5.3. MIPS for specific materials (tons/ton).

t0503.eps

At the Wuppertal Institute in Germany, MI values were calculated for a number of materials including many used in building construction, as shown in table 5.3. Construction was found to account for almost 40 percent of the material flows in Germany.

As with all products, there can be good sources and bad sources—for example, an efficient cement factory versus a polluting factory, or a sustainably managed forest or a looted one. Most conventional buildings and building materials come with a high life-cycle cost today, particularly when plastics are an important part of so many products. Many building products are environmentally damaging, may be unhealthful as is or when wetted or burned, and may require potentially harmful glues and finishes.

Reducing transportation costs is also important. Importing granite countertops from Europe is made possible by subsidies for fossil fuels and ignores external costs. Plundering tropical forests to make more durable decks is as foolish as cutting the giant redwoods to build fences was in the United States.

Some building materials are easy to recycle (steel, copper), but many are very hard or costly to recycle (PVC pipe, asphalt shingles). Many have environmental effects that were not appreciated until recently—these include lead, galvanized steel, and copper. We haven’t used lead pipes for a long time (for human health reasons) and are replacing lead solders, but many countries still use lead flashing on roofs. Water analysis in urban areas has found that lead, copper, and zinc from galvanized roofs are also very common ecotoxic pollutants in water.

Improving the service life of materials is also important. The desire for lowest possible first cost has led builders and developers to embrace cheap materials and low-quality windows, sinks, and electrical fixtures. Many have a lifetime of twenty years or less. Life-cycle costs are high because the labor and material costs to replace low-quality products are high. A high-quality stainless-steel kitchen sink should last a hundred years or more; a low-quality steel sink with poor enamel or porcelain may last only five. A cheap window may last ten years, a good one hundreds of years.

The challenge of sustainable buildings is to use materials that have low MI costs and a long service life. A well-detailed earth or lime-plastered straw building with recycled stainless-steel sinks and a recycled metal roof would have very low MIPS. In northern New Mexico, these metal roofs often work well for forty years or more, and they also facilitate rainwater harvesting.

Material Flows

The flows of materials through the world should be mapped carefully so we know where they end up in terms of people and the environment. Even in developed countries we often have very little information. At best we are tracking the most toxic materials, such as the heavy metals cadmium, lead, chromium, and arsenic, and a few of the more than one hundred thousand chemical compounds now in use. However, most of the effort has been expended on understanding human health risks, and the more complex and challenging understanding of the toxicology of materials on ecosystems remains in its infancy.

To understand both human and ecosystem effects from building materials and supplies for maintenance, we need to know several things:

1. What is the spatial distribution? How much is there? Where does it come from? Where does it go? Does it move in air, water, food, dust? Is it local or global? Concentrated or diffuse? Are materials biomagnified?

2. What secondary effects or pathways are there? Are metabolites or breakdown products more hazardous? Even if materials are nontoxic to humans, do they lead to ecosystem catastrophes (ecotoxicity)?

3. Are effects cumulative or instantaneous? Lethal? Mutagenic? Teratogenic? Can we and/or ecosystems shed materials if exposures are infrequent or do they build up?

4. How persistent are the materials in the environment? Do they break down in hours? Days? Years? Millennia? Can they be collected and destroyed or recycled?

Some materials are relatively easy to recycle, but PVC pipe, urethane foam, composite plastic wood (TREX), and others are end-of-life products. Most of the products used in building and maintenance have not been studied in detail.

Energy Cost

The energy cost of building materials has been studied more carefully than the environmental or health impacts and costs of materials. This is important because as much as 10 percent of all energy use in the United States may be for building construction and maintenance. Transportations adds quite a bit of energy cost to most materials. Few are locally produced, and many are shipped internationally. Preliminary studies suggest the energy costs for typical construction materials and labor, shown in table 5.4.

Table 5.4. Energy cost BTU/unit.

t0504.eps

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Fig. 5.48. Plotting low-embodied energy materials in Texas by Center for Maximum Potential Building Systems.

If we add up the material energy cost and construction cost we can estimate energy intensity by building type. This has not been done very often, but table 5.5 shows how one study mapped the energy intensity.

Table 5.5. Energy intensity.

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To give a sense of perspective on the quantities of material and energy used, a 2,000-square-foot wood-framed house might use about 16,000 board feet of lumber and 6,000 square feet of structural panels. These weigh about 24 tons, and the impact for these wood products alone might be 100 tons of abiotic impact (waste, erosion), 7 tons of air pollution (accounting for transportation would increase this dramatically), and 360 tons of water (again, accounting for transportation would increase this dramatically). The energy cost might exceed 35,000 kWh of energy just for the lumber.

However, when we look at life-cycle costs, it becomes clear that operation and maintenance are much more important than material cost for buildings. This same house might directly use 3,600 kWh of electricity a year, so within twenty years the building energy cost will probably be matched. The lifetime may well be one to five hundred years, although repairs and replacements will be needed.

We Can Do Much Better

The energy cost of constructing a passive solar straw bale or adobe house may be only a tenth or a twentieth as much as a conventional building, as shown in table 5.6. If we use energy-conserving design the house will have an oiled mud floor, vigas (round rather than sawn beams), wood-bond beams, rubble trench foundation, and a willow roof deck. Almost the entire structure can be built using local materials. The exceptions are the window glass, insulation for the roof (although cattail fuzz or bagged straw could be used), and metal roofing. The vigas may have to be hauled in as well, but require no other energy. The energy cost of this structure is shown in table 5.6.

Table 5.6. Energy intensity of a 1,000-square-foot straw bale home with locally cut roof beams, puddled adobe floor, and metal roofing.

t0506.eps

We may not all be able to do this well, of course, but we can do much better than we do today. Consider lifetime energy cost and environmental and health impacts as well as energy savings. The initial energy cost of a good passive structure built with energy-intensive materials may equal the energy use for space heating and cooling over eighty years, while for a typical house it only represents about fifteen years. By using energy-efficient materials in a passive solar house, as in the adobe example above, this factor can be reduced dramatically and the life-cycle energy cost will be very low indeed. When true energy costs (including health and environmental impacts of energy production) are counted, then all buildings will start to include these sustainable materials and design choices.

Local Control

Peter van Dresser was one of the first to fully understand this issue, and he described local development in an ecological context in northern New Mexico in A Landscape for Humans (1976*). The Center for Maximum Potential Building Systems (CMPBS) in Austin, Texas, has done extensive local resource mapping and developed appropriate material solutions that fit the local bioregion; they encourage others to study these issues. The key is to understand what you have, and to use it well. In some cases the availability of materials will influence choices of natural heating, cooling, and ventilation designs.

Community Building

In addition to using local material resources, we also need to assess local human resources and capability for using and repairing them. One of the great advantages and joys of the straw bale building movement has been the ease of participation for people and children of all skill levels.

Toxicity Reduction

Some building materials are potentially harmful to people during construction; many more are harmful if they get moldy or burn in a fire. Many materials have environmental effects that are often still ignored—and the ecotoxic effects of most building materials have not been studied.

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Fig. 5.49. A good test of a building material: How do you feel about your child playing with it or eating it?

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Fig. 5.50. Straw bales for wall and ceiling insulation.

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Fig. 5.51. Building community by working together in straw bale building.

Building Materials and Systems with Green Advantages

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Fig. 5.52. The top nineteen green building materials (for more detail, see the reference section).

Sustainable Materials in a Sustainable Design

The goals in design and building-material choices should be joy in use, health, durability, minimal environmental impact in manufacturing and maintenance, ease of recycling, and low life-cycle cost. Wood, mud, clay, straw, stainless steel, stone, glass, and ceramics are excellent. Gypsum plaster is better than wallboard, and mold-proof wallboard is better than conventional. Insulation that can be removed and reused (cotton batt, polyester batt, fiberglass, mineral wool, cellulose) is preferred over insulation such as foil-faced or sprayed plastic foams that are very difficult to reuse or recycle.

fig.5.53.tif

Fig. 5.53. To allow development of real costs via the life-cycle assessment and the potential of cradle-to-cradle life-cycle design, we need to quantify potential “waste” to resource connections.

More natural materials will be used once we start counting these costs. Even the simplest materials, like adobe, can last a very long time—as the buildings of the Middle East and the pueblos of the Southwest have shown. And these materials can be used to build structures that delight the senses, and are healthy, economical, and durable.

fig.5.54a.tif fig.5.54b.tif

Fig. 5.54. Construction waste. (a) Typical discards. (b) Salvage material sorted for reuse—often without cutting.

This type of quantification has started. An example is the Baseline Green Study done by G. Norris, P. Fisk III, R. MacMath, B. Bavinger, and J. McClennan along with the staff at the center for Maximum Potential Building Systems, which was funded by the US Environmental Protection Agency (EPA) see fig. 5.53.

It consists of cellular tracking of the life-cycle of products for 12,500,000 businesses and industries in 52,480 spatial cells tracked by the US Bureau of Economic Analysis with environmental data from the US EPA, including greenhouse gases, criteria air pollutants, and toxic releases. It allows analysis at global, state, regional, and community scales. This includes material sourcing, processing, transportation, distribution, use, and resource product footprints.

The manner in which we design and engineer buildings throughout their life cycle determines 40 percent of our environmental impact as a country and can increase our local and regional job multiplier from two- to sixfold. Tools like this can have immense effects on our triple-bottom-line economic condition.

The designer, builder, occupant, and community leaders can take many steps to reduce waste and improve reuse. These include specifying sustainable and recycled materials and making it easier to reuse salvaged materials. Vancouver, BC, has walked the walk: The material reuse research facility was built with reused materials. The EPA has started funding reuse research and educational materials, including a deconstruction handbook for residential construction. Associations and groups are also working to develop reuse solutions for common construction and demolition (C&D) materials, including asphalt shingles, drywall, and concrete (www.cdrecycling.org). Habitat for Humanity, cities, private firms, and other nonprofit groups have also set up and manage construction recycling centers. Many cities now maintain a directory of certified and uncertified recyclers to assist builders in providing outlets for C&D discards.

Construction Discards

About a third of the discards in the US waste stream are estimated to be from construction, demolition, and remodeling. This amounted to about 170 million tons in 2003. C&D waste for new construction can be virtually eliminated by careful design and management of materials when constructing a new home or building. Wastes can also be minimized when renovating and/or undertaking a full-scale demolition and removal, though this is sometimes complicated by previous choices and materials that have been found not to be safe after all (lead, asbestos, PCBs, CFCs, and so on). A recent study in California showed that even with current recycling/reuse technology, more than half of the discards from C&D could be reused. With more advanced treatment, recovery rates can reach 90 percent. For example, painted wood, considered nonreusable in the California study, can be safely field-cleaned as demonstrated at Fort Ord (Chartwell School, 2006*). For new nonresidential construction in California, the potential recovery was 86 percent, see chart (Cascadia, 2006*).

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Fig. 5.55. Potential C&D recovery in California nonresidential construction.

Design for deconstruction can play a critical role in minimizing future wastes. This includes keeping components and materials separable and safe and providing future occupants and deconstructors with a building plan and as-built photographs. A deconstruction plan may one day be included in the building-commissioning package. Design for reuse can be more effective than design for recycling, though both are important. In the future, building materials should be bar-coded to make source separation more efficient and less costly. Sprayed foam, glues, and binders can all make deconstruction very difficult. Screws, nails, and other fasteners can often be recovered or removed in ways that allow for reuse or recycling.

Reducing or eliminating the ecological impacts of building-material sourcing, processing, and manufacturing is also important. Straw bale buildings are a good example of a local, renewable, and low-impact material that is easy to recycle. Waste from trimming and cutting is easily returned to the earth. Durability of straw bale buildings is excellent with good detailing—straw bale buildings in Nebraska and Alabama remain in excellent condition after more than seventy years—but when deconstructed the bales could easily be broken down and composted.

Green Discards

More than 30 million tons of green resources are discarded by homeowners and businesses every year. Most of this could be eliminated by better design choices and changes in maintenance. An increasing quantity of green discards is collected separately and composted by cities every year. However, most would be better recycled and reused at home or at the business.

Compost is one of the better uses. Compost is simply the biological degradation and transformation of organic solid waste by aerobic decomposition. By providing the ideal blend of nitrogen (greens), carbon (browns), and decomposition organisms, the appropriate moisture level, and turning or fluffing regularly, compost will heat up. The high temperatures help kill weed seeds and pathogens and speed up the decomposition process. A temperature of 150°F is often considered desirable for pathogen control. More casual compost piles also work, since compost will “happen” even if you just pile on yard and food waste, water sporadically, and wait. Neighbors may be less forgiving of casual composting. Chipping and shredding can reduce the volume and speed decomposition. A cooperatively owned or neighborhood shredder/chipper can make composting more attractive.

Compost can play a critical role in reducing water consumption by trees, shrubs, and gardens. It can also reduce stormwater runoff and erosion. Home sheet composting, compost piles, bins, and tumblers, and vermicomposting can all play a role. The heat from composting has also been used to warm greenhouses, heat water, and heat homes.

Larger materials such as tree trunks can be milled into lumber, as is done at the Green Waste Recycle Yard in Berkeley, California, and comparable programs in other cities. Many older trees have valuable wood. Large planks of walnut, oak, maple, and other species favored by woodworkers are collected, milled, and sold.

Sheet composting is very effective but underappreciated (promoted in permaculture and other management systems). Sheet composting can be as simple as leaving lawn clippings on lawns or spreading leaves, clippings, and cuttings under trees and shrubs; or it can involve chopping weeds, watering, and adding soil amendments and then a layer of cardboard or multiple layers of wet paper under a deep layer of mulch or compost. Many homeowners feel clippings are bad for lawns, but a reeducation effort on the value of clippings for lawn health reduced annual disposal by 94,000 tons a year in Montgomery County, Maryland. Many university extension programs and environmental groups offer composting instructions and training geared to local conditions. Many areas now offer training to become a certified master composter.

Compost bins and tumblers also work and may be more appropriate for town houses or multifamily units. Many communities have encouraged the use of composting bins and/or provided them at reduced cost to minimize the cost of green waste handling. Contra Costa County in California, for example, offers composters at about half price. Homeowners are also eligible for a composting discount of $1.50 a month on their garbage collection fee. This would offset the cost of the bins within three to five years.

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Fig. 5.56. Closing the cycle. (a) Nature’s cycle = no waste. (b) Industrial cycle = waste.

Closing the Cycles

The developer, building designer, and builder profoundly affect the amount of waste and impacts of waste of a home, neighborhood, or city. They can make it easy or hard for the occupant to make sustainable choices. While it is possible to live a more sustainable lifestyle even in a poorly designed and built home, it is much easier in a sustainable home. Very few studies have been done to understand the resource flows through the home, neighborhood, and community, their costs and impacts, and the opportunities they provide for recovery or reuse. The health and ecological impacts of waste are significant, including water pollution, disease, and ecosystem impacts.

Measure to Manage

As we often say, “What isn’t measured, isn’t managed.” The garbology research project at the University of Arizona (beginning in 1973) has provided some very clear information on what is used and discarded and how it behaves after it is sealed in a landfill. The resource waste is appalling. In the United States, for example, the average American discards almost 5 pounds a day. This adds up, and every year we throw away 250 million tons of municipal “solid waste.”

Many of these discards can be reused, recovered, or recycled. They include 77.5 million tons of paper, 33 million tons of green waste, 70 million tons of food waste, 3 million tons of e-waste, hundreds of thousands of often ecotoxic cleansers and disinfectants, and 5,000 tons of pharmaceuticals and personal care products.

The overall US recycling rate is about 30 percent, but many communities, including Seattle (near 50 percent overall and 87 percent for single-family residential curbside materials), have done much better. San Francisco passed a mandatory source-separation ordinance in June 2009, which came into effect in October. The first of its kind in the United States, the ordinance requires residents and businesses to separate organics and recyclables from the garbage. “This ordinance essentially makes sure that no matter where you go in San Francisco, you’ll have opportunities to recycle and compost through the city’s curbside programs,” says Robert Reed, city recycling director.

Waste minimization has received less attention. This is particularly important for hazardous materials that sicken or kill people and ecotoxic materials that sicken or destroy ecosystems. These include a wide range of hazardous materials in cleaners, paints and solvents, batteries, electronics, and biocides. Use in the home is a problem, but use in home landscaping is also critical. Lawns and landscaping use not only much of the increasingly scarce water, but also more than 1 million tons of fertilizer and 67 million pounds of pesticide every year. These materials cause problems for public health and local and global ecosystems.

A single home or business can make many steps toward zero waste, but it is much easier in a community that has adopted a zero-waste program. Some resources are hard to recycle or repurpose at the individual level, but can more easily be managed at the neighborhood, city, state, or national level. In many cases, the imposition of impact fees will help change behavior. After instituting per-bag fees for trash, per-household trash generation in Dover, New Hampshire, dropped from 6.2 pounds per day to only 4.7, and the city’s residential recycling rate increased from 3 to 52 percent (Platt and Seldman). Neat and clean home and neighborhood recycling centers can make it easier to keep material separated, and easy to recycle or repurpose.

Zero-Waste Communities

Education and supporting facilities can also be effective. The goal is increasingly to reach zero waste, something several communities, including Del Norte (California), Boulder (Colorado), Austin (Texas), Palo Alto (California), and others have embraced as a goal. Nantucket Island has perhaps come closest, with 92 percent recovery. Education is essential to help homeowners and businesses understand what can be reused and recycled, what goes together, and what must be separated.

This section can provide only a short introduction to this book-size topic. It includes a short review of several key issues that are easily changed by design and behavior to reach for the zero-waste home and development. It is important to begin by rethinking the nature of the things we throw away: Are they really waste, or are they potentially reusable or recyclable discards that we no longer want? In most cases, they are potentially repairable, reusable, or recyclable. These include construction discards, green discards, food discards, e-waste, product discards, packaging discards, hazardous materials, and ecotoxic materials.

Always remember: There is no “away,” and waste = food. Waste minimization is all about optimizing resource flows.

Return to Nature

One of the most important aspects of sustainable development is returning to systems that facilitate the return of organic wastes to nature and technical materials to the industrial cycle. This is not as hard as it might appear to be. Too often we simply have not tried to complete the cycles and to return materials to use. Organic materials are easily captured and recycled at the neighborhood or city level. Technical or industrial materials often must be captured and repurposed at the regional or national scale.

The neighborhood scale is ideal for composting. Compost can be prepared, maintained, and distributed by the landscaping service. It is easier to keep neighborhood green waste clean and safe than it is to manage a citywide program. It also reduces the travel cost of shipping the compost around and can complete the nutrient cycle if it is used to grow food in neighborhood farms, gardens, or edible landscaping. Village Homes, in Davis, California, with its own vineyard, orchard, and gardens/farm, shows what can be done.

Battery Park City Conservancy in Manhattan developed an innovative organic lawn maintenance program using compost teas that has been operating successfully for more than fifteen years. Although many people are afraid the compost piles will smell, the BPCC compost manager has the experience to prove that composting, when managed well, doesn’t produce any unpleasant aromas. “We’re composting 20 yards from the Ritz-Carlton Hotel,” T. Fleisher explained. “We never have complaints about the odor coming from our site—we have complaints about starting work too early.” Harvard University’s FMO Landscape Services recently tested this system and found that the compost tea makes an excellent fertilizer providing high-quality, readily available nutrients and helping to close the nutrient cycle. The health of lawns and landscaping improved, water use decreased (30 percent), and costs for chemical fertilizer and biocides dropped. Home or neighborhood level use of compost tea will play an important role in reducing the health and ecological impacts of lawns and landscaping.

Although home, institution, or neighborhood use is best, city programs can also be effective. More than half the cities in California now have green waste collection programs. These are often well run and provide compost for sale or free. These collection programs can have a harder time keeping compost clean and free of biocides. Concerns over air emissions from composting are leading to calls for covers and filters in affected areas.

Methane emission avoidance can be used for carbon credits in some areas. Eosta in the Netherlands is developing this option, third-party verified, with its SMR subsidiary in Cape Town, South Africa, with a goal of recovering 95 percent of green waste. Organics can also be used to produce bio-gas. Sweden has been a leader in this effort and now has bio-gas-powered cars, buses, and trains. Palo Alto is trying a bio-gas production facility as well.

It is important to keep compost clean of hazardous or ecotoxic materials. These include common contaminants such as herbicides, fungicides, and insecticides from lawn “care” products. Educating the public about the need to keep green waste clean is often essential. Native and edible landscaping that can be maintained without toxic chemicals should be favored. Use of toxins should entail impact fees to support monitoring and education efforts.

Food Discards

Food discards are the third-largest component of generated waste by weight, and they can also be recovered at home or at the neighborhood scale. The garbology group’s research suggests that each American throws away 1.3 pounds of food a day, or about 500 pounds a year. This is more than double the previous US Environmental Protection Agency estimate. This includes trimmings, leftovers, spoiled, out-of-date, overripe, and simply unwanted food. There is also a great deal of waste throughout the food supply chain from the farm to the wholesaler to the market to home. Most of this is not recycled or reclaimed. The current recovery rate for food waste in the United States is estimated at below 5 percent, but research is limited and very incomplete.

Home recycling by composting, feeding to chickens, pigs, guinea pigs, or other animals, or burial in the garden is not uncommon in rural areas, but little studied. The impact of food waste on the environment has also not been well studied, but we do know that when food waste decomposes in an anaerobic environment it releases methane, a greenhouse gas twenty-one times more powerful than carbon dioxide. Thirty-four percent of US methane emissions are from landfills.

Organic kitchen waste poses a problem in the liquid waste stream as well if it is ground up and flushed down the sewer. The food waste adds problem materials such as suspended solids, oils, and grease to wastewater treatment plants. It also increases the levels of biochemical oxygen demand (BOD), and chemical oxygen demand (COD), using up the available oxygen in water, resulting in oxygen levels that are too low to support aquatic life. Garbage grinders (disposals, disposer, garbarators, or garbagerators) should not be included in new homes unless a significant fee is added for use.

The neighborhood scale is excellent for food-discard recovery. A piggery, chicken coop, and guinea pigs could be managed alongside the neighborhood compost treatment center. Peruvian families often feed guinea pigs kitchen wastes, and later eat them as a source of protein. Animals can also make good use of food waste from dropped fruit in the community orchards and excess produce from the neighborhood gardens.

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Fig. 5.57. (a) Happy piggy. (b) Guinea pig condo, Peru.

Aerobic Food-Discard Processing

Most of the relatively small amount of food waste that is collected is composted or treated using aerobic decomposition. BioCycle reported ninety food discard recycling programs in 2009, up from just forty in 2007 (Yepsen, 2009*). “Alameda County finally has 100 percent saturation, with organics collection offered to all 403,000 households,” says Brian Matthews, senior program manager for StopWaste.org. Wayzata, Minnesota, has collected green waste and food waste separately since 2005. This reduces hauling efficiency, but makes it easier to balance the mix for the right C:N ratio and to keep it clean.

Seattle and other cities have emulated the more common European practice of co-composting green and food waste. Single-family homes are required to participate in either curbside food and yard waste or home composting. All wastes including meat and dairy are collected. More than 90 percent of homes now participate.

Institutional food waste can also be collected and composted. In many cases, these single sources generate large enough volumes to be worth pursuing. Food waste may account for more than a third of school waste, but with an active waste management plan it can be reduced and recycled by co-composting with green waste. One elementary school in Kings County, Washington, composted almost a ton of food waste in one year. Five high schools in San Francisco were diverting almost as much every week. How food is served also matters. The Davis Joint Unified School District realized a net savings of $4,695 in one year by implementing “offer versus serve” in three schools, separating food scraps for vermicomposting, and using recyclable trays. The Berkeley, California, and Pittsburgh, Pennsylvania, school districts’ organic food programs both encourage on-site use of food waste for compost and return to the gardens.

fig.5.58.tif

Fig. 5.58. Stackable vermicompost bins. Food scraps go in the top. The worms digest lower layers then crawl up to the fresh layers, leaving a superb soil amendment behind. Worm tea can be harvested as a super-fertilizer from a drain valve on the bottom bin level. Wire mesh is suggested to keep dogs and other critters out of the tea.

Anaerobic Food-Waste Processing

Waste processing without oxygen results in fermentation, which causes organic compounds to break down by the action of living anaerobic organisms. As in the aerobic process, these organisms use nitrogen, phosphorus, and other nutrients in developing cell protoplasm. However, unlike aerobic decomposition, the anaerobic process reduces organic nitrogen to organic acids and ammonia. Carbon from organic compounds is released mainly as methane gas (CH4). A small portion of carbon may be respired as CO2.

The bio-gas from landfills is often partially collected and used to run landfill operations, but capturing it all is difficult. It is easier if the food waste is treated in a closed reactor vessel managed to produce bio-gas. Food waste may also be digested with sewage and some green waste. In Oakland, California, the East Bay Municipal Utility District’s (EBMUD) Main Wastewater Treatment Plant co-digests food waste with primary and secondary municipal wastewater solids and other high-strength wastes. Anaerobic digestion of pulp from the EBMUD food-waste process provides 730 to 1,300 kWh per dry ton of food waste applied.

The City of San Jose is working with three private partners to produce 900,000 gallons of bio-gas using German technology and 150,000 metric tons of organic waste generated by San Jose residents (Lorinc, 2009*). The city estimates that the project will reduce its greenhouse gas emissions by the equivalent of 1,800 vehicles a year.

Sweden leads the way with 7,000 bio-gas cars on the road and 779 bio-gas buses. Linköping has been using bio-gas since 1997, and the city buses and vehicles have used nothing else since 2002. Twelve public bio-gas filling stations were set up in 2005. A bio-gas train with a 600-kilometer range runs from Linköping to Västervik. It was much cheaper than converting the diesel line to electric, which had been considered to reduce emissions.

Vermicomposting

Worms can also be used to process food waste. Even if you don’t have access to, or permission to use, a backyard or side yard, you can compost indoors with a worm bin. Like any urban composting option, worm bins do require some time and attention; they’re not trouble-free—nor is worm-bin composting for everyone. The best materials to add to a worm bin are washed fruit and vegetable scraps, coffee grounds and filters, tea bags (remove the staples—they harm the worms’ stomachs!), eggshells, paper napkins and towels, and dead plants and flowers. Remember to feed worms a varied diet and don’t overload the bin with fruit, or you’ll attract fruit flies. Do not feed your worms meat, fish, or dairy products. These items will produce odors and attract flies as they decompose. Interestingly enough, vermicomposting has proved to be very useful in treating medical wastes—but this requires much more sophisticated management.

Recovery of Industrial Discards

E-waste

E-waste is among the most hazardous wastes in our homes. Older computers and electronics often include materials like mercury, lead, and cadmium that are harmful for people and the environment. In 2007, the United States generated more than 3 million tons of e-waste, but only 13.6 percent was recycled according to the EPA. Most was buried, some was burned in incinerators, some was dumped in the countryside, and a bit of it burned in home or commercial building fires.

Table 5.7. E-waste in millions.

t0507.eps

Where e-products are still functional, the best solution is to find someone who wants them. This can be facilitated by nonprofit groups or government exchange programs (www.mncfs.org/donate-your-technology; www.epa.gov/osw/conserve/materials/ecycling/donate.htm). Cell phones and computers often can find new uses in the United States or abroad. Half of the cell phones collected by recyclers can be reused after personal data is removed and new software is installed. The recovery rate could be dramatically increased with government incentives for reuse and support for computer disk scrubbing, reformatting, and distribution. Design guidelines based to the cradle-to-cradle approach could also facilitate recycling.

Although the recovery of e-waste should be a national program, states and local governments have made some efforts to improve recovery. Landfilling some types of e-waste, particularly monitors, has been outlawed in many states. In 2008, California, New York, and Maine had rules outlawing disposal of cell phones in the trash. Other states, like California, now charge a disposal fee when new e-products are sold. This helps fund recovery efforts and e-waste recycling days. Companies like HP, Apple, Dell, Toshiba, Sony, and others are also making greener, cleaner computers with much less harmful ingredients. In January 2009, Toshiba had the highest-rated such laptop. Look for a gold ranking and high EPEAT score. The best solution in the long term is extended product responsibility, where the manufacturer has to take back any products made. This can be an effective marketing opportunity, not simply a burden.

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Fig. 5.59. EPEAT label.

Product Discards

Many of the other products people throw away can also be reused, recycled, or returned to nature. A wide range of products, from clothing to furniture and appliances, are thrown away when new items are purchased. Often they are in good condition but no longer serve the needs or desires of the owner. The challenge is to make it convenient to recover these discards. Reuse used to be a common option before sanitary landfills were created. Products would be dropped off at the dump and picked up and used or resold by someone else. Today the alternatives are to donate the material to a group like Goodwill, to freecycle it, or to drop it at a free exchange site. The Nantucket Island waste reduction effort includes an exchange site.

Charitable organizations will often pick up materials at the home, or offer convenient drop-off sites. One of the more impressive recovery efforts is the Goodwill program in Portland, Oregon. The sale sites are modern, clean, and efficient, looking like an upscale store not a thrift shop. Goodwill Industries of the Columbia Willamette currently operates thirty-six retail stores, four outlets, two online retail locations, and nearly sixty attended donation centers. Their retail business turned more than 143 million pounds of used clothing and household goods into $88.8 million in sales revenues in 2008. And this money provided services for twenty-three thousand people with disabilities.

Freecycle is a growing movement that started in 2003 with about forty people in Tucson, Arizona. Freecycle now has almost five thousand participating organizations and seven million members in eighty-five countries. Freecycle.org uses the power of the Internet to help find new homes for usable products.

Reducing your product impact is easy. Buy well-made, durable products made with green materials. Take good care of them and they will last many years, decades, or lifetimes. A good example is a cast-iron frying pan in place of a plastic-coated steel frying pan. The cast-iron pan is nonstick if it is maintained properly and has a lifetime measured in hundreds of years. The plastic-coated frying pan has a lifetime of three to five years, and if overheated on the stove or in recycling produces a gas that is deadly to birds and not good for other living creatures. Buy cotton, bamboo, wool, or linen clothes. When they wear out, use them as cleaning rags and then toss them on the compost pile.

You can also help by asking your decision makers and political representatives to embrace extended product responsibility for all products. If a manufacturer knows it may have to take a product back, it becomes adept at making it easier to take apart, repair, refurbish, or recycle. Industry is already getting on board with zero waste and research into greener materials and industrial ecologies that mimic natural systems. One of the first was established in Kalundborg, Denmark, more than thirty years ago. Considerable research on developing these types of systems has now been done, but implementation is lagging. Improved consideration of true costs of materials and emissions will drive conversion to these more complete industrial systems.

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Fig. 5.60. The industrial ecosystem of Kalundborg, Denmark.

Packaging Discards

About a third of the waste stream in the United States is packaging, but US government policies and laws generally have not addressed packaging wastes, per se, as a distinct class. These wastes include cardboard, paper, steel, aluminum, and a range of plastics and other materials. The metals, paper, and cardboard are relatively easy to recycle, but the plastics are not. Plastic-coated papers and boxes, often used for food, also pose problems. The growing use of multilayer metal, plastic, and paper containers is also a problem.

You can reduce packaging to some extent by buying in bulk at the grocery store, using cloth or recycled plastic shopping bags, and by buying products that are not overpackaged. Buying at bricks-and-mortar stores or looking for used or recycled products can help reduce packaging at your home but may not reduce packaging waste overall very much. Clothes, for example, often come to the stores overpackaged in small boxes with paper, pins, and cardboard. Retailers could encourage much less wasteful packaging using reusable containers.

The best solution for packaging would be a national law similar to the German Packaging Ordinance (passed in 1991). This requires industry to take back, reuse, and/or recycle packaging material. Germany targeted packaging material because it accounted for about 50 percent of the volume and 30 percent of the weight of municipal solid waste. The German approach allows industry to determine the specific implementation mechanisms, rather than have the government oversee or micromanage the system. The German government has imposed no taxes or fees and is not involved in creating markets for recyclable materials. This strategy has allowed industry to create an alternative take-back packaging system, the Duales System Deutschland (DSD), provided that the system meets specified collecting, sorting, and refilling quotas. The DSD is a privately operated public limited company. Consumers can unpack products and leave the packaging in the store so they can avoid the waste fee at home. This encouraged much more efficient packaging systems. The European Union followed this up with the 1994 Directive on Packaging and Packaging Waste. For all materials other than plastics, most EU member states achieved or surpassed the 1994 directive’s minimum recycling and recovery targets well ahead of the June 2001 deadline.

Hazardous Material Discards

A surprising number of hazardous materials can be found in almost every home. An inventory of the garage, kitchen, bathroom (under the sink and in the cabinets), and workshop will usually include a wide range of hazardous materials. These include corrosive, toxic, ignitable, or reactive ingredients. Household hazardous wastes include certain paints, cleaners, oils, batteries, and electronics. Pesticides, rodenticides, chemical fertilizers, motor oil, antifreeze, batteries, paint thinners, solvents, fluorescent lightbulbs (mercury), computer and TV monitors, printer ink and toner, drugs and antibiotics, medical/biohazard waste, compressed gases (propane), and other highly toxic items should always be treated as hazardous waste. Improper disposal of household hazardous poses a threat to human health and the environment.

Proper Disposal

Many communities offer options for safely discarding household hazardous waste. These may include free disposal days at schools or at a waste site for paints, oil, et cetera. Check your government Web site for local programs. In some cases, these collected materials are recycled or reused. Paints, for example, can often be resold or combined by type and resold. Finding a proper outlet for disposal of unneeded drugs and antibiotics is more difficult, but it is clear that flushing them down the drain (once recommended) is inappropriate. Federal laws should be amended and improved to ensure control of prescription and nonprescription drugs and antibiotics. Guidelines for safer wrapping before disposal in landfills are provided online. California maintains a list of facilities that can accept drugs and is developing a comprehensive plan. Ultimately a product take-back rule with free mailing may be required.

Use Greener, Cleaner Materials and Methods

The many products used around the home are increasingly recognized as a source risk. You can take a quick look at these at the National Institute of Health page, http://hpd.nlm.nih.gov. Soaps, surfactants, disinfectants, and cleaners are very helpful around the home, but they can be harmful for human health and ecosystems. The foams that are frequently seen in many urban creeks are an indication of how much soap and detergent is entering the environment. Soaps tend to be very well tolerated by mammals but can be toxic to insects, both the harmful ones (controlled by soap sprays) and beneficial or harmless insects in aquatic ecosystems.

fig.5.61.eps

Fig. 5.61. Triclosan contamination. Source: EWG.

Antimicrobial compounds are even more of a concern. Widely used materials such as triclosan have been approved by the EPA for use on more than 140 products without adequate testing. Triclosan persists in the environment, breaks down into substances highly toxic to wildlife, pollutes the human body, and poses health risks that are barely studied and poorly understood. This might make sense if it worked well, but a review of studies on the efficacy of triclosan in soap revealed that it did not reduce bacterial counts on hands significantly more than plain soap unless used repeatedly and in relatively high concentrations (greater than 1 percent, compared with the 0.1 to 0.45 percent in consumer antibacterial soaps; Aiello et al., 2007*).

Norway’s national consumer council and food safety authority called for a ban on products containing the antibacterial compound triclosan in 2005. The Environmental Working Group has been working for a ban on triclosan in personal care products and any other products used at home for the United States. This is in line with the conclusion of the Canadian and American Medical Association’s belief that common antimicrobials for which resistance has been demonstrated should “be discontinued in consumer products unless data emerge that conclusively show that such resistance has no effect on public health and that such products are effective at preventing infection.”

Be Informed

Read labels carefully and try greener alternatives around the home. Many books are now available with a wide range of green cleaning techniques using readily available and safe materials such as vinegar and lemon juice. A wide range of cleaner, greener paints are now available as well. You can use compost or compost tea on lawns and gardens instead of chemical fertilizers. Cedar chips or cedar cupboards can replace mothballs. Biocontrols and organic treatments can be used in the garden. And boric acid can replace commercial ant and roach killers.

Ecotoxic Materials

Ecotoxic materials are a special concern for sustainable buildings. Many materials are not harmful to people, but can be very disruptive for ecosystems. These include materials that can be leached from roof materials or paints, such as copper, zinc, and lead, biocides and fertilizers from landscaping, biological wastes, drugs and personal care products in sewage (which is still often dumped in rivers untreated during high storm flows in communities with combined storm and sewage systems), and biocides and cleaners from around the house and garage. Cars and driveways also leak oils, gasoline, antifreeze, and other ecotoxic materials. Most families discard cleaners, solvents, paints, pharmaceuticals, and personal care products (PPCPs) that make their way to our local lakes and streams from landfills and sewage.

In 2000, the US Geological Survey sampled downstream from wastewater treatment plants in thirty states and found at least one pharmaceutical in 80 percent of 139 streams. In some streams, hormones and hormone mimics have led to unisex fish populations that do not reproduce. Triclosan was one of the most frequently detected compounds. Even more worrisome was that fact that when researchers added triclosan to river water and shined ultraviolet light on the water, they found that between 1 and 12 percent of the triclosan was converted to dioxin in the water, leading to fears that sunlight could be transforming triclosan to extremely dangerous dioxin in the environment.

Zero Waste

The sustainable home or building is a building that minimizes discards and facilitates reuse and recycling. Materials should be clean, green, and durable, requiring little or no maintenance. When maintenance is required, it should be with safe materials and processes. The design of the building and landscape should also minimize stormwater contamination and stormwater runoff and would include space and support for recycling, repair, reuse, and return to nature with composting. Neighborhood, community, and state-level support can make it easier and more attractive to minimize discards, ensuring that discards are reused, repaired, recycled, or returned to nature. Minimizing the discard stream is desirable and can be advantageous to the pocketbook as well as to health and the environment. Nature provides the best examples of zero waste.

Zero waste can be difficult to achieve, but 90 percent reduction is possible and proven. Industry has led the way with many facilities now seeking, and sometimes achieving, close to zero waste on-site. These include production of cars (Subaru, Indiana), tea (Lipton, Virginia), electronics (Xerox, New York), and wines (Fetzer, California). David’s parents came close, reducing their trips to the landfill to one garbage can a year.

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Fig. 5.62. Choose wisely: a toilet bowl cleaner warning label.

Landscape Regeneration

Regenerative Design of Places

In his book Regenerative Design for Sustainable Development, John Lyle describes most environmental design as being either part of a degenerative process that degrades the environment or part of a regenerative process that helps maintain our environment. Sustainable design is, by definition, regenerative design as well. Our impacts have been so great that a significant design effort must be made to regenerate degraded environments and landscapes while simultaneously providing for human activities and needs. This is similar to the relationship between life-cycle assessment and life-cycle optimization where the goal of doing “less harm” is expanded to doing “more good.”

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Fig. 5.63. The landscape context of each building project should be analyzed in regard to the scales of place as described in The Importance of Place. This is to determine how each project can be a working part that enhances the whole.

To allow landscape regeneration to become part of our design processes, we need to once again acknowledge how dynamic natural environments really are. This is important in facilitating the modification of two mind-sets that get in the way of a successful practice of regenerative design.

The first of these mind-sets is the tendency to think of natural landscape as being in equilibrium outside of human effect. Accordingly, protection and continued stability are viewed as the goal. Federal policies in the United States with regard to fire prevention and flood protection have been large-scale examples of this mind-set, since flood and fire are assumed to be destructive natural disasters. But fire and flood control have created new, more costly extreme wildfires and floods. We have recently discovered that some non-equilibrium is a critical aspect of the health of many ecosystems. Thus, these federal policies are slowly being modified to create “controlled burns” in some national forests and “controlled floods” in areas downstream from some large dams. We are slowly coming to realize that the occasional disturbances we call “natural disasters” are an important part of the maintenance and operation of ecosystems and landscapes.

Life-cycle and regenerative design as applied to site is necessary in many settings, including regional, urban, town, suburban, and rural. Some argue that sustainable design, particularly architecture, should be strictly concentrated in existing built-up areas, leaving more rural areas intact. It is true that more urban areas need a great deal of attention, and the distinction between urban and rural places should be maintained and strengthened. We need to recognize, however, that very few rural areas are pristine, intact, and healthy; and that the urban edge is the area of most extensive impact. Industrialized mining, agriculture, and recreation practices have affected all our places except, perhaps, a few we designate as wilderness. Even these have been affected by climate change, nitrogen deposition, acid rain, and other pollutants. Therefore, sustainable design using life-cycle and regenerative principles needs to be applied almost everywhere. The differences are only in the specifics of landscape, relationship to density, and infrastructure.

This does not mean the continuous disturbances accomplished by existing degenerative design are desirable. Instead, it means that occasional disturbances are often an essential part of the system. There can be fires, earthquakes, and landslides in Mediterranean biomes; fires, floods, and intense grazing by hoofed animals in grassland biomes; floods, droughts, and tornadoes in the midwestern United States; ice storms in the Northeast; hurricanes and typhoons in coastal subtropical and tropical areas. Disturbance and regenerative processes are occurring constantly at multiple scales. We, too, in fact, must become a part of this dynamic process. All we have to do is tune in to the specificity of place to understand some part of it, and then design can be a regenerative, rather than degenerative force. We can’t ever know everything that is involved and we can’t control nature. It is far more important to hear the music and start to dance. With familiarity and practice, the steps will improve.

Example of Integrated Design for On-Site Resources

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Fig. 5.64. The Trout Farm, 1995–1997. (a) North facade straw bale wall. (b) Aerial photo. (c) Site plan. (d) Facility plan.

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Fig. 5.65. (a) Micro-hydro power unit. (b) Milling lumber from trees killed by the fire. (c) Infrastructure and material flow plan.

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Fig. 5.66. (a) West facade. (b) Structure, finishes, and furniture made from milled trees. (c) Straw bale wall plan.

Our final example of integrated design for these topics is a multiuse complex near Santa Margarita, California. This design in figures 5.64–5.66 responds to the requirements of providing a home and office, healing the site after a severe wildfire, and addressing some of the problems found in the greater Trout Creek watershed from damage done from 1910 to 1979 by mining, grading, and motorcycle racing. Sporadic wildfires are also a major design factor in this location. Healing the watershed required controlling erosion caused by all these factors to the point where water flows are regenerative rather than degenerative. In addition, infrastructure, energy production, and materials used for construction were drawn from the existing conditions.

The dead trees from the wildfire in 1994 were milled on-site, yielding more than 20,000 board-feet of high-quality custom lumber at a reasonable price. Regeneration of the landscape occurred in waves, starting with specialized fire-following plants like fire poppies, progressing through herbs and low shrubs to larger shrubs and brush to regeneration of the forests. In seven years, the landscape took on much of its previous character.

The architectural program for this site is for a mixed-use complex of offices, research, and residential facilities. The complex is designed to draw most of its energy for heating, cooling, lighting, and electrical generation from the site by passive means. In addition, 80 percent of the wood used in construction was obtained from the site.

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Fig. 5.67. The Trout Farm section drawing.

Summary: Harvesting On-Site Resources

As has been stressed throughout this book, the passive approach to green building and sustainability is an integrative approach. Historically, the passive approach dealt just with thermal issues such as heating and cooling; then environmental issues such as ventilation and natural lighting were included, as well as materials and construction processes. But today, this approach to design is also dealing with resource use and production issues such as water, food, waste, and much more. The more expansive considerations include the responsibility of the building to landscape, ecosystem, and planet. In addition to these are the social dimensions and issues of sustainability.

All of these concerns are exemplified in the Tierra Nueva Cohousing community in Oceano, California. This twenty-seven-unit community utilizes many of the techniques described in this chapter—passive heating, cooling, natural ventilation, natural drainage, separate automobile areas, green roads, multiple community facilities, open space, a community solar photovoltaic array, and a mature sustained landscape. Beyond incorporating all these are the social aspects that enliven living there. In the words of Jim Leech, co-housing developer, “Community is the hidden dimension of sustainability.”

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Fig. 5.68. Tierra Nueva Cohousing. (a) Site plan. (b) Green access road. (c) Retention basin playground. (d) View from common house to units below. (e) Interior of residential unit.