11.1 Introduction
Nighttime lighting is so ubiquitous, and such a commonplace component of urban spaces, that it readily fades into the backdrop of daily experience. The historian of technology David Nye (2010) remarked that nighttime illumination has become so normalized that it seems natural, and temporary blackouts now seem unnatural. But it is because of its omnipresence that it must be scrutinized, for artificial illumination is formative to our urban nighttime experiences and resultant moral judgments. Lighting shapes the spaces and defines the boundaries of urban nightscapes, effectively creating city nights on both a physical and symbolic level. Historians of city nights and lighting technologies have shown that illumination has been equally important for its practical applications as for its influence in shaping, and being shaped by, various societal values—for example, safety, policing, nightlife, and progress (e.g., Brox, 2014; Koslofsky, 2011; Nye, 1990; Schivelbusch, 1988; Schlör, 1998). Understood in this way, “Light is far more than “infrastructure” in a narrow sense of technological networks, but encompasses a range of developments including material and symbolic dimensions to state formation, the coevolutionary dynamics of different modes of governmentality, and the delineation of distinctive forms of public culture ranging from the mundane to the spectacular” (Gandy, 2017, p. 1096). In this paper I provide a forward-looking analysis of an additional dimension of increasing importance, namely the environmental values and human-environment relations influenced by artificial nighttime lighting. I will consider how these factors can inform the design of streetlights, and more generally, how we can re-think the design of our urban nightscapes via new technologies and evolving moral concerns.
We are on the precipice of two converging changes to outdoor lighting, which will profoundly change how we light cities at night. The various forms of electric lighting that have dominated the twentieth century are poised to be replaced by light-emitting diodes (LEDs), which has been described as a shift from electric to electronic lighting (Gandy, 2017). Concurrent to LEDs is the introduction of a variety of “smart lighting” applications and systems, adding another layer to the shift towards electronic outdoor lighting. The controllability and, most important, the efficiency of smart LED lighting has fostered the rapid development and uptake of this technology, with an increasing number of cities across the world undertaking lighting retrofit projects.
At the same time as these technological developments, a growing acknowledgment of the adverse effects of artificial nighttime lighting is causing a paradigmatic shift in evaluative judgments. Commonly referred to as light pollution, these negative impacts are far reaching: nighttime lighting has been shown to cost (and waste) billions of dollars and enormous amounts of energy, effect human health and well-being, disrupt ecosystems, and cut off experiences of the natural night sky (Stone, 2017). Growing recognition of light pollution has resulted in a shifted moral landscape, with over-abundant and poorly designed illumination being scrutinized for its inefficiency, as well as the resultant “disappearance of darkness” (e.g., Bogard, 2013). This has led to a re-evaluation of darkness, previously seen as foreboding and dangerous, now increasingly perceived as a threatened source of cultural and environmental value (Stone, 2018b). This complicates the adoption of smart LED lighting technologies, as current retrofit strategies—while championing lower costs and energy efficiency—are expected to exasperate many adverse effects of light pollution. Concerns have been raised regarding their impacts on ecosystems and human health, as well as the likelihood of further degrading dark skies and stellar visibility (e.g., Falchi et al., 2016). Furthermore, despite the promises of smart LED lighting, studies suggest they may ultimately lead to greater energy usage if not accompanied by new policies and strategies (e.g., Kyba, Hänel, & Hölker, 2014; Kyba et al., 2017).
This confluence of technological innovation and changing moral evaluations creates complex challenges for a ubiquitous but critical urban infrastructure. Yet, it also offers a rare opportunity to re-imagine how and why we light our nights, and to envision and enact new strategies. Taking into account the shifting terrain of technical and moral factors, this paper will articulate a morally engaged design strategy for the adoption of (smart) LED lighting. In particular, this paper will focus on how to incorporate environmental values into the next generation of streetlights. To do so, designing for darkness will be introduced as a framework that strives to foster a range of environmental values through the design of nighttime lighting. Though darkness is identified and presented as a design goal, nighttime illumination is not actively de-valued. Rather, the focus is on achieving a better balance of illumination and darkness, and letting dark skies—as a form of ecological restoration—back into our urban spaces. Through applying this framework, I will propose that the functionality of smart LED lighting can be exploited in creative and innovative ways that supersede a narrow focus on efficiency and achieve a broader range of environmental values.
It is important to recognize the momentous and rare opportunity created by the present convergence of technical and moral changes, as well as the stakes. In the longer history of public lighting, we can observe that major technological leaps happen at a somewhat gradual pace, roughly once every century or so. It seems that we are now in the early stages of the next leap, replacing the technologies that have lit the twentieth century and shaped contemporary debates. We can thus assume that the transition to smart LED lighting will come with a large degree of physical and temporal permanence, and may very well shape the next century of urban lighting—technically, politically, and morally. In the face of light pollution, as well as lighting’s contribution to global problems such as climate change, we cannot let this opportunity pass us by. We are encountering a rare moment where we can re-imagine our urban nightscapes, and envision how twenty-first century nights could, and should, look. The values that have driven the proliferation of electric lighting must be met with scrutiny, and re-purposed to fit contemporary needs and goals.
Streetlights constitute the primary source of nighttime illumination, making them fundamental to any strategies addressing light pollution and incorporating the positive aspects of darkness into urban nightscapes.1 Globally, there are estimated to be over 100 million streetlights in use. There is an estimated additional 55 million lights used for parking lots in OECD countries alone. Together, these sources make up over 90% of outdoor illumination (with traffic signals, billboards, and airports making up most of the remaining 10%). As could be expected, illumination outputs are not evenly distributed globally—the 35 nations of the OECD use 71% of the energy and produce 75% of the outdoor illumination (International Energy Agency, 2006). Streetlights are especially important for cities, being essential for urban nighttime activities and constituting a significant portion of electricity consumption and costs. In the United States, for example, outdoor lighting is estimated to cost about $10 billion annually (enough energy to power six million homes for a year), and can account for up to 60% of a city’s public amenities electricity bill (Murthy, Han, Jiang, & Oliveira, 2015). Major cities typically have tens of thousands of streetlights, or more. For example: Washington, DC has over 70,000 publically owned streetlights (which are bound for LED retrofit in the coming years), Helsinki has approximately 85,000 streetlights, Milan’s recent LED retrofit saw the installation of 100,000 new lamps, and New York City has approximately 262,000 streetlights. While such numbers serve as useful illustrations of the prevalence of streetlights, most important for this discussion is the recognition that streetlights constitute a massive and critical infrastructure. They are foundational to nighttime illumination, as well as the problems of light pollution.
The paper progresses as follows. The next section provides practical details to inform the later discussion, both introducing and describing the benefits and (potential) harms of LEDs and smart lighting systems. In Sect. 11.3, I articulate a move towards environmentally responsible lighting, using Responsible Innovation as a value-sensitive orientation to guide the development and design of nighttime lighting. Designing for darkness is then presented as a technology-specific form of Responsible (Urban) Innovation (Nagenborg, 2018), and defined via two interrelated components: the substantive environmental values to be fostered and preserved, and the striving for morally engaged nighttime experiences. Section 11.4 then explores how to operationalize a designing for darkness approach. First, it is translated into a tangible design goal aimed at addressing the issue of “shifting baseline syndrome.” Next, three design concepts are put forward as actionable strategies to guide the re-introduction of darkness into urban nightscapes. Throughout, this paper relies on some (basic) lighting terminology—a quick reference guide for these various terms is included as an Appendix.
11.2 LEDs: The Next Generation of Streetlights
Lighting consideration | LED advantages |
|---|---|
Efficacy | • High luminous efficacy (lumens/Watt), with rapid improvements in recent years; assuming that LEDs reach their projected efficacy of 200 lm/W by 2025, this can result in up to 40% energy savings for all lighting by 2030 |
Efficiency | • High efficiency (lower power consumption, lower operating voltage, reduced energy costs); can be up to 50% more efficient than HPS lamps • Longer lifespan; can last 3–6 times longer than HPS lamps |
Environmental impacts | • No mercury; no UV or IV radiation |
Controllability | • Easy dimming control compared to current technologies • Less light spillage, better directional light output |
Lighting quality | • Vivid colour range and control • Cool white light (high CCT) allows for improved colour rendition |
Discussions of potential improvements often use high-pressure sodium (HPS) lamps as a benchmark, as it is the most efficacious and affordable precursor. As of the International Energy Agency’s (2006) report, about 62% of outdoor lighting was high or low-pressure sodium, and 30% mercury vapour.
Alongside the conversion to LEDs, new streetlights are increasingly being fit with “smart” technologies, often with the stated goals of further improving the benefits described in Table 11.1. The label of “smart” for city systems and master plans has been met with scrutiny, for there is no clear consensus about the meaning or boundaries of the label, or its actual benefits (e.g., Kummitha & Crutzen, 2017; Sadowski & Pasquale, 2015). However, at the most general level, smart technologies can be understood as the use of ICT or Internet of Things (IoT) technologies for infrastructure and public services. We can therefore broadly understand “smart lighting” as the incorporation of ICT or IoT technologies to lighting—for example, adaptive controls, sensors, etc.—with the goal of improving performance (e.g., Juntunen et al., 2015; Murthy et al., 2015). For streetlights, this typically means incorporating sensors or cameras to light poles and fixtures towards the goals of increased (cost and energy) efficiency and safety (NAS, 2017). LEDs, given their controllability, are ideal for coupling with smart lighting systems, which has made for a high degree of complementarity between LEDs and smart lighting initiatives (Gandy, 2017). For example, Juntunen et al. (2015) prototyped a smart LED lighting system that was responsive to both natural lighting levels (e.g., increased brightness levels after a fresh snowfall, as well as during sunrise and sunset) and pedestrian activities. Through these innovations they were able to see significant power reductions, and further predict that smart LED lighting can offer up to 70% energy savings—far more than just switching lighting to LEDs.
Despite the potential benefits brought by (smart) LEDs, both scientific researchers and advocates for light pollution reduction have voiced concerns over the rapid proliferation of LED outdoor lighting. At the most general level, seeing LEDs as an environmentally sustainable infrastructure solution “is highly ambiguous because their introduction facilitates the development of more energy-efficient sources of light pollution” (Gandy, 2017, p. 1097). Gandy (2017) further asserts that LEDs, as a more efficient and cheaper source of lighting, could lead to a dramatic increase in light consumption. Kyba et al. (2014) also predict that an adoption of LEDs may not decrease energy consumption, unless linked with strategic and effective policies. A more recent study seems to support these warnings, finding that at a local scale there may be savings, but at a global (and often national) scale this is not the case—likely due to rebound effects and the installation of lights elsewhere (Kyba et al., 2017). There is also concern that LEDs will increase skyglow, the ambient atmospheric brightness caused by nighttime lighting, arguably the most conspicuous form of light pollution. It has been estimated that the replacement of current technologies with cool white LEDs could more than double skyglow levels in Europe (Falchi et al., 2016), further cutting off experiences of the night sky, especially in cities. Finally, there are concerns about the long-term health impacts caused by blue-rich white LEDs (American Medical Association, 2016), as well as the ecological impacts (Schoer & Hölker, 2017a). A proposed solution is to promote warmer colour temperatures, which may mitigate some of the harmful effects to humans as well as skyglow. However this decreases efficacy, and a recent study suggests this will not decrease the ecological impacts of LEDs (Pawson & Bader, 2014).
In sum, we can observe that LED outdoor lighting is being met with both optimism and scrutiny. As with any large-scale infrastructure, they carry a range of (potential) positive and negative effects. While the extent to which LEDs will exasperate negative environmental effects is still under debate, as is the exact costs of wasted light, these concerns nevertheless signal that there is a broad range of environmental issues at stake. And, the exact impacts will likely not be known with certainty until a greater number of LEDs have been installed and in operation for a longer period of time. Of course, by then the possibility of reversing any negative effects will be much more difficult. Regardless of these debates, it seems that barring some dramatic and unforeseen policy or market shift, their widespread adoption will continue over the coming years. We should therefore see this moment as an opportunity to anticipate downstream issues and explore alternative pathways that supersede a shortsighted focus on efficiency. For this, I propose that we strive to proactively incorporate moral values into the design and use of this new technology, without dismissing the potential benefits that LEDs (and smart lighting systems) can provide. By doing so, we can actively search for ways to reframe existing debates, take into account a full range of environmental concerns before the infrastructure’s design and use is solidified, and articulate a value-sensitive framework for the adoption of this new technology.
11.3 Designing for Darkness: A Value-Sensitive Approach to Responsible Nighttime Lighting
How then to incorporate the instrumental benefits of new innovations, while also avoiding downstream detrimental impacts, in the development and design of new lighting technologies? To orient such an approach to urban nighttime lighting, I use Responsible Innovation as a starting point. At its most general level, this concept adds the qualifier of responsibility (via transparent, inclusive processes and the articulation of ethical end goals) to innovative practices (e.g., van den Hoven, 2013; Stilgoe, Owen, & Macnaghten, 2013). Nagenborg (2018), in the context of urban technologies, defines Responsible (Urban) Innovation via three key features. First, it requires that the ethical and societal implications of products and projects be considered. Second, it emphasizes a non-instrumental view of technologies, asserting that they are not value-neutral but instead value-laden. Third, innovations should strive for ways to include values in the design process that do not at the same time have a negative impact on other moral values. This problem of satisfying conflicting obligations or moral values is referred to as moral overload (van den Hoven, Lokhorst, & van de Poel, 2012). However, the very notion of Responsible Innovation—to innovate in a way so as to “expand the set of relevant feasible options regarding solving a set of moral problems” (van den Hoven, 2013, p. 82)—is conceptualized as a way to overcome such conflicts. Importantly, this necessitates a shift in how we conceptualize innovation—no longer just about technical improvements but also about ethics and moral values (van den Hoven, 2013). When applied to technologies embedded in urban contexts, this can take the form of either the responsible design and use of a technology in the urban environment, or more constructively exploring how new innovations can be developed to address specific urban challenges (Nagenborg, 2018).
As an example of an urban challenge specific to nighttime illumination, we can briefly look at the tensions between darkness and safety. In helping to avoid injury and find your way at night, lighting serves a necessary functional requirement for urban nightscapes. But beyond these basic practical functions, the effects of lighting are a debated issue. Recent studies examining the contentious relationship between crime and lighting—as well as the complex relationship between feelings of safety, actual safety, and fear of the dark—tend to show that while actual safety may not increase with more illumination, feelings of safety often do (e.g., Boomsma & Steg, 2012; Fotios, Unwin, & Farrall, 2015; Gaston, Gaston, Bennie, & Hopkins, 2015; Haans & de Kort, 2012; Marchant, 2004; Li et al., 2015; Pena-Garcia, Hurtado, & Aguilar-Luzon, 2015). Further, the associations between lighting and safety are deeply embedded connotations, with the goals of safety and security (as well as policing and surveillance) inexorably tied to the very foundations of modern public lighting efforts (e.g., Schivelbusch, 1988; Schlör, 1998). This relied on both a practical and symbolic interpretation of safety, as artificial illumination inherited a much longer history of lighting-as-good and darkness-as-evil cultural metaphors (Ekirch, 2005). We can thus appreciate that lighting-as-safe and darkness-as-dangerous associations are deeply embedded perceptions. However, neither are essential or static concepts, but influenced by our lighting practices. It would therefore appear that we are confronted with a situation of moral overload, and thus a challenge for responsible lighting strategies. While an in-depth analysis of the relationship between safety and darkness is outside the scope of this paper, Sect. 11.4 will put forward innovative approaches to incorporating darkness into urban nightscapes without necessarily compromising safety.
Taking Responsible (Urban) Innovation as an orientation for light strategies requires a re-framing of the goals driving innovations to nighttime lighting, moving beyond technical improvements as the primary goal for future lighting systems. The current focus on efficiency and cost-savings are certainly important goals for a municipality, however a value-sensitive approach emphasizes that other “non-functional” requirements also be incorporated into the development, design, and adoption of technologies and systems (van den Hoven, 2013). We must therefore begin with a value-level discussion, and then ask how these technical capabilities can be developed to serve desired goals. Only then, with goals clearly identified, can we judge the responsible usage of new lighting technologies, and how they may address the environmental impacts of nighttime lighting. For this, we need a framework that articulates morally relevant values as a starting point and uses them to better elucidate the “good” we can strive to achieve with smart systems and LED streetlights. Put otherwise, it forces us to ask, exactly what we are designing for?
A framework for responsible urban lighting must respond to the unique historical, social, and technological context of nighttime illumination. For conceptualizing the environmental values at stake, I propose the adoption of darkness as a key design feature to be sought after in future nighttime lighting strategies. To understand exactly what it can mean to design for darkness, and what such an approach would entail, I first present the substantive values associated with darkness. This leads into a longer discussion about how meaningful experiences can be wrought out of our urban nightscapes through a conscientious (re)introduction of dark skies. While focused on the positive features of darkness, this approach is not meant to de-value lighting or the various benefits nighttime illumination undoubtedly brings. Rather, it is about highlighting the many benefits that darker nights, combined with a restrained and conscientious use of lighting, can bring. Hence, it is ultimately about situating darkness as a design criterion and value-level consideration in nighttime lighting, and in the process achieving a better balance of lighting and darkness (Edensor, 2015, 2017). However, given the over-illuminated state (or at least poorly-designed illumination) of most of our cities, this requires an explicit focus on re-introducing darkness into our urban nightscapes. Also important to emphasize is that this approach is focused on elucidating and realizing environmental values. This is not to say that social or procedural values are less important, or should not be considered in future innovations to outdoor lighting, only that environmental impacts are the topic at issue here.
11.3.1 Valuing Darkness
The nine values of darkness translated into prima facie obligations to consider in the design of nighttime lighting; adapted from Stone (2018b)
Value of darkness | Prima facie obligation derived from value |
|---|---|
Efficiency | The responsible use of lighting where and when needed; money-saving |
Sustainability | The responsible use of lighting where and when needed; energy-saving and preserving non-renewable resources |
Ecological conservation | The protection and preservation of species and biodiversity; habitat conservation efforts |
Healthiness | Promoting and fostering human health; physiological well-being |
Happiness | Promoting and fostering happiness; emotional well-being |
Connection to nature | Preserving a connection to the more-than-human world |
Stellar visibility | Preserving conditions for access to the firmament |
Heritage and tradition | Preserving the cultural heritage of the night sky for future generations |
Wonder and beauty | Preserving the aesthetic appeal of the natural night sky |
Towards operationalizing for the design and use of LED streetlights, the value of darkness can be further refined in two ways. First is a consideration of how darkness, as an environmental good, should be weighed in comparison with other values associated with both darkness and lighting. For incorporating darkness into this broader landscape of concerns, the nine values are further translated into prima facie moral obligations that future lighting strategies should—at the least—take into consideration (Table 11.2). Thus, each is presented as a first-order requirement in the design process, even if each obligation may not be achievable in every case. However, this creates an important shift in the burden of proof—to show why not to incorporate the obligation, and give justifiable cause for that choice (Stone, 2018b, pp. 622–623).
Second is a consideration of how to weigh and prioritize the nine identified values internal to darkness. Darkness has instrumental value, both from an anthropocentric and non-anthropocentric point of view. For example, it can be economically valuable, saving money and reducing energy usage, and can promote eco-tourism via “dark sky reserves.” And, it is beneficial for many nocturnal species. Darkness also has intrinsic value, in the sense that there are reasons to preserve darkness for non-instrumental reasons. Certain phenomena and experiences, such as the starry night sky, are an inherent and inseparable quality of dark nights. In such cases, darkness is not a means to an end, but a facet of the end goal itself. These intrinsic qualities, I assert, should be the focus of a designing for darkness approach on two grounds. First, they are more robust, in the sense that they offer enduring, powerful experiences that are not contingent on external goals (e.g., cost-saving efforts). Second, achieving them will necessarily lead to instrumental benefits. Achieving darker skies offers the possibility of reconnecting urban spaces with their natural settings, but it will also lead to a reduction in energy usage, cost savings, and health and ecological benefits. To the contrary, installing energy-efficient lighting may achieve instrumental benefits while remaining neutral, or even having a negative effect, on access to the night sky. Thus, the cluster of values associated with dark skies (ecological conservation, connection to nature, stellar visibility, heritage and tradition, and wonder and beauty) is prioritized as the main goal for environmentally responsible urban lighting.
11.3.2 Experiencing Darkness
Darkness, as presented above, can be understood as an evaluative concept to define and categorize the environmental goods to be strived for in nighttime lighting. However, darkness is also a quality of lived experience—there is a physicality and spatiality to darkness, just as there is one to lighting. And, it is through such experiences that meaning ultimately arises. We must therefore understand darkness as both an evaluative concept and an experiential goal. This means that in addition to articulating darkness as something of value, we must also explore how darkness can be realized in urban nightscapes in ways that foster morally transformative, or at least morally engaged, experiences.
To properly situate the positive features of darkness into the context of lived urban spaces, it is important to understand the relationship between lighting and darkness, and how nighttime illumination shapes our perceptions of darkness. A basic presupposition of Responsible Innovation is that technologies are value-laden, and lighting is no exception. The many histories of nighttime illumination (e.g., Schivelbusch, 1988; Schlör, 1998) have done excellent jobs of highlighting the various values that have shaped, and been shaped by, nighttime lighting—a topic I summarize elsewhere (Stone, 2017). Here though, I will not discuss these various values further, but rather focus on the phenomenology of human-technology-environment interactions; or more specifically, the interaction between nighttime experiences, lighting technologies, and darkness. This requires that we appreciate the moralizing role lighting plays in shaping our perceptions and evaluations of darkness, and the capacity of lighting technologies to either foster or hinder those valuable aspects of darkness described above.
To understand the profound influence that technologies have on our morality, we can draw from recent work in technological mediation (Verbeek, 2011). Focused on human-technology relations, it interprets our actions and perceptions as “always closely interwoven with the material environment in which they play out” (Verbeek, 2011, p. 22). Technology is not something out there to be dealt with. Instead, our interactions and uses of technological artefacts play an active role in constituting our reality. Hence, we experience the world—and morality—through or by way of technological artefacts (Verbeek, 2011).2 Urban infrastructures thus act as external constraints, limiting our ability to perceive beyond them, both figuratively and literally, as well as shaping how we see ourselves in relation to the natural world (King, 2000).
As discussed in the introduction, streetlights dominate our nights. They are the most prominent source of illumination, both historically and in contemporary cities, effectively creating nighttime spaces (Major, 2017). Streetlights are an encompassing technology that not only mediate perceptions, but are foundational to our experiences and understanding of the city at night. They provide the backdrop and ambient lighting for all nighttime activities. In this sense, streetlights actively constitute our nights, both literally and figuratively. They are at the crux of the question of how darkness is perceived, and ultimately evaluated. Any attempt to re-introduce and re-imagine darkness must therefore begin with the lighting technologies themselves. To design for the value of darkness, we must focus on our lighting. Only by first appreciating that our cities are understood from within the illumination created by streetlights, can we move to re-design them in a conscientious way.
A designing for darkness approach must therefore acknowledge the profound mediating power of nighttime lighting, and strive for the incorporation of meaningful experiences of darkness through the design of streetlights. Given the hierarchy of substantive values identified above, such designs should strive to incorporate the intrinsic, future-oriented values of darkness into urban nightscapes. For hints at how such meaningful experiences could look, here I draw on the idea of a re-envisioned nocturnal sublime discussed in more detail elsewhere (Stone, 2018a). It is argued that focusing on incorporating the desirable aspects of dark nights—namely the starry night sky—into urban settings can engender aesthetic responses that are relevant to fostering an environmental ethic. The proposed re-envisioned nocturnal sublime is further situated as a form of holistic urban restoration (de-Shalit, 2003; Stone, 2018a). On a practical level, it helps to mitigate the negative impacts of light pollution, and satisfies the instrumental benefits of darkness (e.g., a reduction in energy usage). Yet it also attends to the moralizing effects of lighting infrastructure, in the process fostering the intrinsic value of dark skies. It allows for a glimpse beyond the lighting that now envelops our urban nightscapes, and opens the possibility of cities and their inhabitants (re)discovering an ecological and cosmological sense of place. Speaking about the future of “green” design generally, the architect James Wines (2005, p.18) stated, “The mission now in architecture, as in all human endeavour, is to recover those fragile threads of connectedness with nature that have been lost for most of the century.” Experiencing the sublime night sky in cities can help to re-discover one of those “fragile threads” of connectedness with nature, and bring it back into our urban spaces. Thus, we can extend ideas of “greening” cities to also include “darkening” city nights as a form of environmentally restorative urban design.
11.4 Designing for Darkness: Practical Possibilities for (Smart) LED Streetlights
Designing for darkness provides a value-sensitive framework for urban nighttime lighting, articulating a range of substantive environmental values that can be fostered through the achievement of darker night skies. It also situates darkness as a form of urban (ecological) restoration, which can help to create meaningful experiences for city inhabitants. A necessary next step is to translate these abstract philosophical ideas in actionable design requirements, and explore how smart LED streetlights can be put towards these goals. Thus, here I take preliminary steps in operationalizing designing for darkness. To do so, I first identify a target issue of relevance to our evaluations and experiences of darkness, namely shifting baseline syndrome. This is followed by three possible designing for darkness scenarios, presented as a means to overcome shifting baselines and re-introduce darkness into our cities.
Recommendation(s) | Suggested policies |
|---|---|
Reduce skyglow, light trespass, and glare | • Properly positioned installations—for overhead lights, angled below 70° from the downward vertical • Fully shielded lighting luminaires to further direct light |
Eliminate unnecessary lighting | • Switching off or dimming lights when not in use, to both reduce light pollution and save energy consumption and costs |
Proper illumination levels | • Establish proper levels of illumination required for safety and visibility. Research suggests only 1–3 lx required for facial recognition and visibility (save for roadways with higher speeds); current streetlights have illumination levels of 10–60 lx |
Proper colour spectra | • Avoid cold white light due to effects on ecosystems, human health, and skyglow; use “warm” or filtered LEDs with a CCT below 3000 K |
Ecological sensitivity | • Maintain naturally unlit areas while promoting and enforcing “dark sky reserves” • Harmonize light levels with the needs of local flora and fauna |
11.4.1 Shifting Baseline Syndrome
A designing for darkness approach can take many forms, and respond to the values and experiences articulated in Sect. 11.3 in varying ways, and to varying degrees. However, it does require a specific orientation: that we assess new innovations to, and uses of, artificial lighting via both their quantifiable impacts and as a manifestation of social and environmental values. For translating darkness into an actionable design goal for LED streetlights, the abstract ideas of “connection to nature” and “mediation” require a tangible focal point for design interventions. For this, I will elaborate on a specific facet of urban nights that makes evident the mediating (and moralizing) capabilities of nighttime lighting, and can be directly addressed through new technological innovations: shifting baseline syndrome. It has been applied to issues of light pollution by Lyytimäki (2013), and is a term originating in ecological conservation research (Papworth, Rist, Coad, & Milner-Gulland, 2009). Lyytimäki (2013, p. e46) explains that, “Shifting baseline syndrome refers to the changing human perceptions of biological systems due to loss of experience of past conditions. Simply put, people may view the current situation as the typical or normal state, even when the ecosystem is considerably degraded compared to earlier states.” Broadly, there are two types of shifting baseline syndrome: generational and personal amnesia. Generational amnesia occurs when previous experiences are not passed on to new generations, causing past conditions to be forgotten; personal amnesia occurs when individuals forget or “update” their own experiences, and come to believe that current conditions are the same as past ones, and thus normal (Lyytimäki, 2013; Papworth et al., 2009). In both cases, it causes a shift in perceived baselines, and thus an evaluative shift in accepted norms.
Lyytimäki (2013) posits that the loss of the night sky, and experiences of (especially urban) nights, cause of both types of amnesia. This assumption is largely supported by scientific evidence that investigates the brightness (and brightening) of our contemporary nights. It is estimated that 83% of the world’s population, and over 99% in the USA and EU, live in areas considered to be above the “polluted” threshold, and in cities the artificial brightness can be several magnitudes greater. The Milky Way—arguably the key feature of the sublime starry sky—is no longer visible to 60% of Europeans and almost 80% of North Americans (Falchi et al., 2016). This trend is only increasing, with nighttime brightness estimated to be increasing 3–6% annually on a global scale (Hölker et al., 2010). And, as mentioned in Sect. 11.2, these trends are not expected to decrease with the adoption of white LEDs, unless new policies are enacted.
In applying shifting baseline syndrome to nighttime lighting, Lyytimäki is mainly concerned with addressing the effects on ecosystem services, typically known as ecological light pollution (Longcore & Rich, 2004), and how this effects value-level discussions about the need and use of artificial lighting. However, Lyytimäki’s argument provides much broader and profound possibilities, offering a new perspective on urban darkness. Shifting baselines of darkness can be understood as the manifestation of lighting technology’s mediating presence in our perceptions of nighttime environments. The repercussions of nighttime lighting on our baseline understanding of darkness can be considerable, as living in constant artificial brightness can lead to perceptions of darkness as unnatural or unsafe (Lyytimäki, 2013). Yet it also reveals that darkness—as both a normative and phenomenological concept—is not essential or static. It highlights the relative nature of everyday perceptions of “darkness” and calls into question evaluative categories such as “too dark.” Such labels are not absolute, but shaped by our abilities to see (or not see) past our current conditions, and our tendencies to update our accepted and expected norms of illumination levels. As nights continue to get brighter, and we introduce new, more efficient technologies, we risk continuing to increase our generational and personal baselines. However, with the controllability offered in new lighting technologies, we can actively challenge this trend. Thus, shifting baselines are where a designing for darkness approach can focus: on seeking to reverse our baselines and re-introduce darker nights, while still maintaining sufficient levels of illumination for nighttime activities. This can allow for meaningful experiences to emerge, as well as the achievement of the intrinsic (and instrumental) values associated with darkness. And importantly, it can allow for the achievement of these goals without creating (or exacerbating) a situation of moral overload between darkness and safety.
11.4.2 Realizing Darkness
As a practical strategy for realizing darker nights—and specifically realizing the values and experiences elucidated in Sect. 11.3—we can thus explore possibilities that directly address our personal and generational shifting baselines. Here three design concepts for darkening cities are presented with these goals in mind. As with any urban planning strategy, a great deal more research into the feasibility and place-specific manifestations is required. However, here these concepts are presented as broadly applicable guiding visions that could be included in planning instruments such as a lighting master plan, as a means to speculate on the real-world potentials of designing for darkness. Each concept should, in principle, incorporate the instrumental benefits of smart systems and LEDs (energy savings, etc.), but also go much further in helping to re-position the relationship between lighting and darkness in urban nightscapes.
11.4.2.1 Concept 1: Incremental Darkening
A straightforward design solution is to quite simply turn down the lights. Current lighting practices typically give rise to street-level illumination of between 10 and 60 lx, which is several magnitudes greater than natural conditions. With no artificial light, a clear sky with a full moon provides an illumination of circa 0.1–0.3 lx, a clear moonless starry sky circa 0.001 lx, and an overcast night sky as low as circa 0.0001 lx (Gaston et al., 2012). Further, current lighting is often very inconsistent in the amount of brightness depending on distance from the light source—something that can be addressed via the uniform lighting distribution of LEDs (Gaston et al., 2012). Recent studies have found that only 1–3 lx is necessary for visibility and facial recognition, although roadways with higher speeds require higher levels (Schoer & Hölker, 2017b). This would suggest that the lighting levels on many of our streets and public spaces could be significantly reduced without necessarily compromising visibility or nighttime activities. This would have a range of economic and ecological benefits, as well as potentially avoiding downstream health issues. And, it would decrease skyglow and allow for increased stellar visibility.
For realizing an incremental darkening strategy, we can take inspiration from other domains of urban planning—for example, Copenhagen’s initiative to reduce vehicle traffic and increase cycling. For several decades, Copenhagen has been gradually “removing driving lanes and parking places in a deliberate process to create better and safer conditions for bicycle traffic” (Gehl, 2010, p. 11). This has been combined with investments in cycling infrastructure, yielding positive results: bicycle traffic doubled between 1995 and 2005 (Gehl, 2010). A similar lighting strategy can be enacted that conscientiously slows, and potentially reverses, shifting baselines. A radical or abrupt change in lighting levels would likely cause concern, and may not be socially accepted. If shifting baselines create the perception that current levels are the norm, any drastic reduction could seem “too dark,” and decrease feelings of safety. To avoid this, we can exploit the potentials of this new technology, and specifically its dimming capabilities, to gradually reduce brightness. Both illumination levels, as well as colour temperatures, could be uniformly reduced in incremental steps, in a way that is not overly impactful on daily experiences. Like Copenhagen, this could be done over several years, and could include regular feedback loops with public input as well as studies on crime and safety. Importantly, such a strategy should be planned and implemented citywide after smart LED retrofits, to ensure a uniformity of gradual darkening and colour changes. Otherwise, this may lead to increased contrast between adjacent spaces, which may have the reverse effect on perceptions of darkness, and perhaps cause (or reinforce) segregation between spaces or neighbourhoods. In sum, this concept positions the act of darkening cities as a long-term process implemented uniformly across an entire city or region, to reverse our shifting baselines and gradually re-introduce darkness into our lived spaces.
11.4.2.2 Concept 2: Environmentally Responsive Lighting
A central goal of designing for darkness is to reconnect cities, and their inhabitants, with an ecological and cosmological sense of place. In doing so, the act of darkening cities can become a form of holistic urban restoration, that lets the night sky back into urban experiences. The smart sensors and systems that offer increased controllability and real-time responsiveness can be developed towards this goal. Illumination can thus be responsive to changing natural conditions (moonlight, clouds, etc.), creating a lighting strategy closely attuned to seasonal cycles and weather.
These technological capabilities already exist, or are under development. Street lighting has traditionally been controlled by a clock, with modern systems often controlled by a photoelectric cell to detect daylight and adjust operating times accordingly. Still, such systems are limited because they operate as binary on/off systems. However, with LEDs, greater control is now possible (Juntunen et al., 2015). Tests have been done in which lighting levels respond to changing environmental conditions. For example, a study in Helsinki found that lighting levels could be significantly reduced when there was fresh snowfall, due to ambient brightness. The same study found that lighting could similarly respond to the brightening sky during sunrise (Juntunen et al., 2015). A similar approach has been suggested elsewhere as a strategy for mitigating light pollution, positing that future lighting systems could respond to changing lighting conditions during twilight hours (Schoer & Hölker, 2017b). Future systems could even incorporate more creative or informative dimensions that are unique to local geographies and social circumstances. For example, lighting could be developed that changes colours or brightness in the minutes before rainfall, or in response to wind speeds, as both a warning system and safety measure.
The key here is to develop sensors towards the explicit goal of illumination that is responsive to, or symbiotic with, natural brightness levels; to see lighting not as eliminating the night, or of pushing back darkness, but of responding to it. At the very least, this will save energy and costs. More optimistically, it can re-connect lighting infrastructure—and city inhabitants—to diurnal and seasonal patterns. In this sense it is less about “darkening” in a literal sense (as in Concepts 1 and 3), but rather attuning cities to their environment’s natural rhythm. Instead of leaving cities awash in a static, uniform illumination from sunset to sunrise, cities respond to their nocturnal context and its idiosyncrasies.
11.4.2.3 Concept 3: Urban (Dark) Acupuncture
The previous two ideas are more gradual, aimed at incremental changes to ambient brightness, and should be implemented somewhat uniformly across a city or region. Another option is to strive for more radical or transformative experiences aimed at a direct and explicit confrontation with darkness, bringing artificial lighting out of the backdrop of daily life. For this, specific spaces—public squares, pedestrian streets, parks, etc.—could be explicitly and conspicuously left dark, perhaps not without any lights, but at near natural levels to contrast our current (perceived) norms. Through this, we can create moments of accentuated darkness throughout cities, to give inhabitants a glimpse of another possibility for urban nightscapes.
As inspiration for such an approach, we can draw from Jaime Lerner’s idea of urban acupuncture (Lerner, 2014). This planning theory posits that a few well-placed “pricks” of a certain service, amenity, or structure can begin a process of urban renewal. The concept is most often applied to social concerns, such as safety, or of “restoring the cultural identity of a place or community” (Lerner, 2014, p. 9). This could mean, for example, strategically placing a new public amenity such as a library so as to stimulate visitors to the surrounding neighbourhood (and thus economic activity, educational services, safer streets, etc.). As another example, Lerner discusses nighttime lighting as a means to accentuate a space and create dynamic, interactive moments. Why not attempt to likewise accentuate a public square or bridge with darkness (perhaps accompanied by some explanatory or educational materials)? Alternatively, a darkened space can serve as a backdrop for a lighting installation, highlighting both the presence of darkness and the beauty of illumination (as well as their complementarity). The controllability of the brightness and directionality of LED lighting could be developed so as to make such moments possible. As an even more radical approach, we can explore how other new and emerging technologies, such as autonomous vehicles, can allow for novel experiences of darkness—an idea discussed in detail elsewhere (Stone, Santoni de Sio, & Vermaas, 2020).
Experiencing darkness—or alternatively, purposeful illumination within a darkened space—could allow moments where people glimpse past the lighting that now mediates our urban lives, and see a nighttime space oriented otherwise. In doing so, we could be forced to confront our (often unquestioned) expectations and perceptions of lighting, and possibly plant the seeds for a new version of darkness to permeate though our cities.
11.5 Conclusion
This paper has presented a forward-looking analysis of nighttime lighting, and in particular streetlights, a critical and formative urban technology. It focused on two interrelated issues: the rapid introduction of smart LED outdoor lighting, and the incorporation of environmental values into the design of public nighttime lighting. To do so, the challenges posed by the introduction of these new technological innovations were re-framed using Responsible Innovation, to argue for a shift from “smart” to responsible lighting. This requires a shift in thinking regarding new lighting strategies—away from efficiency as a primary goal and towards the proactive inclusion of a broader range of values into the development and design processes. Designing for darkness was then put forward as a value-sensitive, and technology-specific, framework for incorporating substantive environmental values and meaningful experiences of dark skies into city nights. Potential strategies for realizing designing for darkness were put forward by first identifying shifting baseline syndrome as a target concern, and then presenting three design concepts that utilize the features of smart LED lighting systems: incremental darkening, environmentally responsive lighting, and urban (dark) acupuncture.
Re-introducing darkness into cities is the primary goal of the approach defined here, as a means to both address the costs and impacts of light pollution, while also more fundamentally re-imagining urban nighttime lighting. However, this goal does not de-value or wholly dismiss the importance of nighttime illumination. Rather, it strives to foster an appreciation of the quantitative and symbolic goods that can be achieved through a better balance of light and dark. It is thus about learning to appreciate the value of darkness, and to experience it—not as dangerous or evil—but as a feature that can reconnect with us with natural rhythms and the starry night sky. For cities, this will not be an impenetrable pitch dark, but a better lighting-darkness balance. “The presence of urban darkness, like a phantasmogoric manifestation of “weeds,” has been characterized as a symbol of disorder, neglect, or abandonment, but there is an intermediate spectrum of illumination that lies between a disorientating gloom and the incessant glare of late modernity” (Gandy, 2017, p. 1102). Through this process, the power and spectacle of artificial lighting can also be re-appreciated. Instead of being seen as a pollutant, the new era of electronic lighting can revitalize the positive symbolism of nighttime lighting, but with the added dimension of environmental values.
Walking in cities at night, therefore, enables us to sense, connect and think with the city around us. We are able to give things our undivided attention, a welcome respite from the ongoing erosion and subdivision of our time and sense of belonging in the world. Deliberately moving out of the glare and stare of our commoditized and highly structured daily routines and into the rich shadows and patina of our cities at night may be one of the few truly beautiful and sublime practices available to us. Far from being dead hours, for the wakeful the night affords investigation and liberation.
In sum, it would seem that a darker future might indeed be on the horizon for our urban nightscapes.
Earlier versions of this paper were presented at the Forum on Philosophy, Engineering and Technology at the University of Maryland in May 2018, and the Philosophy of the City Colloquium at the University of Twente in June 2018. In addition to thanking the audiences for their feedback, I wish to thank Pieter Vermaas and the anonymous reviewer for their written comments on earlier drafts of this paper.