Earthen HomesUsing reclaimed materials is a great way to reduce
our homes’ ecological footprint, and reclaimed materials
can also work as a perfect complement to several
forms of green building. Here, we’ll discuss some of the
green building options available to builders and ways
to improve a home’s efficiency and the affordability
of its maintenance over time.
CONSIDER YOUR CLIMATE and your wishes and desires before choosing a building system. If you live in an extreme climate, a building method that includes thick, highly insulating walls is a good option. Consider examining your region’s vernacular building styles — before the advent of cheap heating and air conditioning, people relied on wise building methods to keep their homes comfortable year-round. Studying this vernacular architecture can give you excellent input on the way to site and design your home to work with your climate. For example, in the South, long, narrow buildings with ventilation on either side encouraged breezes. Large porches shaded interiors, and detached kitchens kept the heat of cooking fires away from the main living space. In the American Southwest, Spain, Greece and Italy, light-colored–adobe structures reflected sunlight, keeping interiors cool. In the frigid Northeast, rounded rooftops on Shaker buildings were designed to shed winter snow. On the plains, long sod homes helped insulate and protect interiors from heavy winds.
Two key elements when considering any building style are insulation and thermal mass. Insulation refers to the amount of conditioned air the home keeps out, while thermal mass refers to the walls’ ability to store and release heated and cooled air. Thermal mass helps regulate temperatures. For example, in summer, a home with high thermal mass walls will cool down overnight, then release cool air as the space warms in the heat of the day. Thermal mass has the opposite effect in cold temperatures, storing the day’s heat and releasing it when nighttime temperatures drop.
Earthen Homes
Earth is one of the world’s oldest building materials. Several models of earthen homes exist. Their thick earth walls can hold and release heat, but they don’t have high insulative properties, making them excellent for warm climates, but not ideal for extreme cold. One of the most recognizable types of an earthen home is the Southwest’s adobe structure that is constructed from bricks. A clay mixture is baked (often in the sun) to form these bricks. Another type, “rammed earth” homes, uses forms that are filled with layers of compacted moist mineral soils. When the forms are removed, the walls are able to support loads. A common method of vernacular building, rammed earth was “rediscovered” as an alternative building method in the 1970s and has been standardized and modernized, according to Rammed Earth Works, a California company. Cob building combines clay, sand and straw to make a slurry that is shaped into walls without machinery. Cob allows for creative structural home construction — walls can be formed to be nearly any shape, and cob creates a charming feel reminiscent of Old World cottages. The straw content in cob gives walls a higher level of insulation, but it is still not ideal for extremely cold weather. Cob has been used for centuries, and medieval cob homes still stand in both Europe and the Middle East.
Straw Bale
Straw bale building is excellent for cold climates because of its thick, well-insulated walls. In these buildings, straw bales are stacked to form walls, which are then covered with thick earthen plaster. The straw bales offer insulation, while the plaster provides thermal mass. Sometimes, building authorities require straw bale walls to have a conventional post-and-beam supporting structure, with the stacked bales as wall filling. Straw bale associations across the country often host work parties, in which group members come together to stack bales and apply plaster. Participating in work parties can offer a hands-on way to learn the building method. Straw bale walls are dense, and frequently straw bale builders include a “truth window” — a small section where earthen plaster is not added so you can peek at the bales on wall interiors. Straw bale is considered a healthy home option because the straw and clay naturally moderate humidity levels, and the breathable walls don’t trap toxins inside. Straw bale is typically not appropriate for extremely humid climates.
Concrete Forms
In any discussion of green building methods, you are likely to hear about ICFs (insulated concrete forms) and SIPs (structural-insulated panels). ICFs are rigid foam forms reinforced with steel and filled with concrete. SIPs are panels of oriented strand board that sandwich a piece of foam insulation. Both products provide excellent insulation and durability, though they do not provide thermal mass — the ability to store and release cooled or heated air. It’s vital that these efficient methods employ excellent ventilation techniques, because the highly insulated walls aren’t breathable. Factory-formed, neither is ideal for the do-it-yourselfer, and they can both be expensive materials, though prices can match those of conventional timber-frame construction due to decreased labor costs, and their extreme efficiency mean these homes can save energy over time.
Cordwood
Cordwood building uses short round pieces of wood (like firewood), stacked and mortared into place. The wood provides good insulative properties, while the mortar offers thermal mass. The wood used in cordwood building would otherwise be considered a waste product in the construction industry, as it’s not in the form of a board. One can also incorporate other materials into cordwood walls, such as glass panels to admit light. The method is fairly easy to achieve without much training.
Timber-framed Construction
German in origin, timber-frame is the ancestor of our conventional building method today, but it uses larger posts that extend from the floor all the way to tall ceilings, and all joints are formed with mortise-and-tenon joinery rather than nails or screws. Generally, the beautiful woodwork in a timber-framed home is left exposed. Though they are beautiful and can be made green using sustainably forested wood, high levels of insulation and alternative energy systems, timber-frame requires an advanced set of building skills. These homes are typically very expensive and very durable.
Light-frame Construction
Light-frame construction is the conventional building method used for most homes in the US. Walls are made of wood/particleboard forms filled with insulation. If using reclaimed boards and healthy insulation, light-frame can work well with reclaimed materials. If you use subcontractors, this is the type of building they will be most familiar with. It is also possible to combine light-frame with other building methods, such as cob or straw bale.
Earthships
Though earthships aren’t a building type per se, they are a design system that incorporates many natural and recycled materials. They follow six main design principles:
• Thermal solar heating and cooling. Earthships rely upon the sun and the Earth’s stable temperature to moderate indoor temperatures naturally.
• Solar and wind electricity. Earthships produce their own electricity with a prepackaged photovoltaic/wind power system.1
• Contained sewage system. Earthships reuse all household waste in treat-ment cells that feed food gardens and landscaping.
• Building with natural and recycled materials. The most important quality in earthship construction is that the main building materials have high thermal mass. Earth, stones, concrete or other thermally massive materials could all be employed. Earthships also use sustainable, indigenous and reclaimed materials. Many are built using reclaimed tires that are filled and tightly packed with earth then stacked.
• Water harvesting. Earthships capture stormwater for use in the home and gardens.
• Food production. All earthships incorporate at-home food production.
The Importance of Design
No matter which building method you choose, it is key to sustainability that our homes are efficient and affordable to maintain. Using reclaimed materials reduces a building’s environmental footprint in terms of materials used. Making smart choices in design and materials selection can go a long way toward improving a home’s affordability and efficiency over time.
If you’re designing a home from scratch, the first consideration is site selection and home orientation. Position a home to take advantage of the sun’s ability to aid in the heating and cooling of homes, a method known as passive-solar design. South-facing windows capture the sun’s heat in winter and direct it to thermally massive interior elements such as concrete and stone, which hold the heat during the day and release it slowly over time. In summer, overhangs block heat gain from the sun, and thermal mass holds cool evening temperatures and releases them during the warmer day. Several building methods that complement the use of reclaimed materials create thermally massive walls. Straw bale is an excellent insulator and provides thick, thermally massive walls. As we’ll see in Chapter 7, the Phoenix Commotion achieves thermally massive walls by incorporating reclaimed materials into concrete.
It’s also important to consider wind speed and direction and other natural phenomena as you site your home. Well-placed windows can help achieve natural ventilation, reducing the need for air conditioning. Ensuring your home is filled with natural light can help reduce energy use from electric lights. Skylights or high clerestory windows help bring sunshine deep into interiors, as do open floor plans.
Proper insulation levels are essential to an efficient home. Plenty of recycled- content and natural insulation options exist. Energy Star offers guidelines for insulation levels in attics and floors.2 In new or renovated homes, achieving high insulation levels is key to creating an efficient home.
Windows and doors are also essential elements of a home’s efficiency. Reclaimed doors are excellent for efficiency. Generally made of solid sturdy wood, antique doors are often more insulating than modern doors, which are often hollow and made from particleboard. Windows are a bit trickier. Though beautiful, historic windows are usually single-pane and very inefficient. Modern low-emissivity, dual- and triple-pane windows provide much better insulating properties than antique versions. High-quality storm windows can help improve the efficiency of older windows, but they can’t achieve the efficiency of new windows.
Be sure to consider efficiency when choosing household appliances, as well. Eschewing a clothes dryer can completely eliminate one source of household energy use. Consider a clothesline (several non-permanent, retractable versions exist) outdoors and/or in the laundry room and a drying rack. For most appliances and fixtures, including clothes washers, refrigerators and toilets, buying a new efficient version is worth its investment in energy savings over time.
Residential sources of renewable energy can reduce maintenance costs over time, especially as unstable energy prices go up in the future. Obtaining low-cost building supplies may help make room in your budget for alternative energy; even if you can’t afford it now, consider designing your home to accommodate future alternative energy systems. Simple design tweaks such as making sure wiring is easily accessible can greatly reduce the cost of adding alternative energy systems, as technology improves and systems become more affordable.
Water savings and processing is another key consideration. Many economists predict that major worldwide water shortages will be our next most pressing environmental challenge. Water use also requires energy; transporting water in and out of your home requires energy, and as much of our water use is hot water, decreasing our water use also decreases our energy spent heat- ing it. Building in ways to manage this increasingly precious resource will help reduce a home’s maintenance costs and improve its environmental footprint.
Several very simple water-saving measures exist: Choose low-flow showerheads and faucet aerators, along with dual-flush, low-flow or composting toilets. Simple graywater systems use water from faucets, showers and clothes washers to irrigate landscapes. You can also design systems that reuse sink water to flush the toilet.
Your landscaping can also be designed to help process water, reducing the amount of water sent to area treatment plants. Select permeable paving or gravel instead of hardscaping. It allows water to go through plants’ natural filtration process and seep into the water table, rather than running off into street gutters and on to treatment facilities. Also consider the grade surrounding your home when designing landscaping. If gutters lead directly to paved areas or the street, you are directing rainwater to sewage systems. Attempt to design your home so rain from gutters flows onto your yard and through a system of plantings, soaking into the ground. You don’t want gutters to dump water right next to the house. Grade landscaping down as it moves away from your home to direct rainwater away from foundations. You can also attach rain barrels to downspouts to collect rainwater for landscape irrigation.
Landscape plant selection also influences your home’s energy efficiency and resource conservation. Choose native plants that are naturally resistant to local pests and are adapted to your climate to reduce the amount of irrigation they require. You can landscape to enhance your home’s efficiency by planting deciduous trees that block summer sun but admit winter sun, planting windbreaks upwind of drafty areas and using plants and trees to shade overly sunny areas and more. You can read more about it in Natural Home & Garden magazine.3
As you plan your home design, reduce its environmental footprint by carefully considering how much space you really need. Limit square footage by using smart, multifunctional design and incorporating lots of storage. Well-designed outdoor spaces also can enhance living area without increasing your home’s square footage. Long views and high ceilings make homes feel bigger. It’s often more environmentally friendly to build up rather than out, limiting the amount of land you develop. If you have spaces you only use occasionally, such as a guest house for children who have moved away or a part-time or seasonal workshop or workspace, you can reduce your main home’s footprint by placing those spaces in an outbuilding not attached to the main home.
The health of your home is also an important element of its sustainability over time. No one is going to want to live in a toxic home. Try to reduce home items that include formaldehyde and formaldehyde-containing glues. Particleboard often includes toxic chemicals. Using reclaimed materials brings its own set of health concerns. Reclaimed materials are more likely to be made of natural materials such as solid wood, and they’re less likely to be chemically treated. However, reclaimed materials with paint on them are likely to contain lead. Don’t attempt to remove lead-based paint. Either paint over it with new zero-VOC paint, or retain its aged look by sealing it with a clear non-toxic sealant (AFM Safecoat makes a few varieties). Carpet often contains synthetic materials and chemical glues; choose natural wool carpet or opt for hard-surface flooring such as reclaimed wood. Carpet can also harbor chemicals tracked in from outdoors.