A Pragmatic Approach to Lighting Policy Incorporating Behaviour: The Example of Light Pollution

Abstract

The use of light at night may contribute to the inappropriate or excessive use or presence of artificial light known as light pollution. Light pollution wastes huge amounts of electricity and money and contributes to global warming as well as having significant impacts on wildlife. There is a recognition that many of the issues that drive light pollution should be engaged by local, often pragmatic, governments. Lighting policies need to manage light pollution while also providing the intended services. To achieve this, local governments could develop policies and interventions in terms of three main considerations: functionality, technology, and the behaviours that comprise social usage. To determine to what extent this is being done, the lighting policies of the local governments of greater Melbourne are investigated, along with the related Australian Standards associated with lighting. Very few of the local governments in greater Melbourne had an explicit policy addressing light pollution and none of them considered the likelihood of behavioural issues such as rebounds in energy use. The results of this study suggest that policies that reduce light pollution, with controls to avoid behavioural complications such as rebound effects, should reduce costs for local governments and reduce greenhouse gas emissions.

1. Introduction

Outdoor Artificial Lighting at Night (ALAN) has fundamentally changed human activity in cities, providing extra time for work and leisure and some freedom from natural light cycles. ALAN includes lighting in car parks, sporting and entertainment venues, roads, paths, and lights outside houses [1]. The widespread availability of light is generally seen as essential for maintaining a lifestyle that is active across more of the hours in the day and has become taken for granted to such an extent that it is particularly noted when that lighting fails [2], indicating that lighting is an essential service. However, the widespread use of light at night is also the primary source of light pollution.

Light pollution can be defined as the inappropriate or excessive use or presence of artificial light [3]. Although light pollution may not appear to be as obviously toxic as a chemical spill, light is one of the most widespread pollutants in the world, with estimates that 99% or more of Europe and the contiguous states of the United States of America have some degree of light pollution [2] and the situation has been on a steady trajectory of growth for many years. Analyses of satellite data between 2012 and 2016 show that light pollution was increasing at around two percent per annum [4]. However, this is likely to be an underestimate given that those analyses were based on measures that excluded blue light. That is, light pollution is widespread, especially in developed countries, and likely to be growing. Light pollution exacerbates air pollution and global warming due to the energy that is wasted, and results in lost money as energy is wasted [1].

Although lacking recent data on the true extent of the impact, estimates from 2010 suggest that for the United States of America alone the cost could be about USD 7 billion per year and 66 million tons in carbon dioxide equivalent terms [5]. Meanwhile, more recent reports from DarkSky International, unsupported by peer-reviewed publications, put global estimates of upwards of USD 50 billion dollars per year being spent on outdoor lighting, with more than 35% of this wasted light that contributes to light pollution. This would equate to more than USD 17.5 billion dollars being wasted per year, contributing about 1% of global GHG emissions, figures largely in line with those of the earlier work of [5].

The main forms of light pollution include overlighting, light trespass, glare, and skyglow [5]. Overlighting occurs when more light is provided than necessary, either due to having too many light fittings (technically known as luminaires) or the selection of luminaires that are too bright [6]. Overlighting can also apply to the duration of light, for example, leaving lights switched on in an office overnight or when the space is not in use [7]. Light trespass is any light that is shining in an unwanted area, such as streetlights shining through your living room window [8]. Glare is light that results in discomfort or functional impairment, due to being too bright or being angled into your line of sight [9]. Another phenomenon related to glare is flicker, which can lead to irritation and discomfort [10] but is often neglected in light pollution considerations [11]. Flicker involves a repeated change in brightness of a light source. In turn, each of these forms of light pollution can contribute to a further form of light pollution known as skyglow if the light is directed or reflected upwards, creating a diffuse glow [6]. Skyglow is sometimes considered to be the characteristic symptom of light pollution, where skyglow results in the loss of visibility of the night sky, covering large areas of the globe and affecting more than 80 percent of the world’s population [12].

Light pollution is of such a scale that symptoms such as skyglow can cover massive areas and it is often studied using satellite data, leading to a growing recognition that many of the issues that drive light pollution should be engaged at a local level [13]. Local governments are a level of government where many specific actions progressing sustainability could take place [14] and are directly responsible for most of the public sources of lights (for example, street lights). Consequently, the cities that local governments manage are often considered as a key focus where sustainability policies and practices could be proactively advanced [15]. However, with varying levels of understanding about light pollution or other sustainability issues across and within local governments, as well as changing political agendas as elected officers change, efforts toward sustainability may not always be progressing or even present in local governments [16]. That is, public managers in local government have been presented with the opportunity to use sustainability as a vehicle for transformative reform, but many are not seizing that opportunity, with sustainability efforts across local governments considered to be, at best, uneven [17].

These uneven results may be because strategic, transformative approaches to sustainability for local governments may be difficult to achieve, needing to be built on appropriate capabilities and enablers, while overcoming the constraints and uncertainties associated with transformative change [15]. However, there are a lot of changes local governments can make without substantial alterations to their strategy and culture, without embracing a sustainability ideology, and addressing light pollution is a good example for demonstrating how such policy could be considered.

2. Informing and Assessing Lighting Policies

Many countries have begun regulating lighting to reduce light pollution and concerned institutions have emerged with a range of recommendations [18]. In Australia, government policies regarding light pollution controls were relatively scarce until the introduction of the National Light Pollution Guidelines for Wildlife [19]. Those guidelines are considered world-leading in terms of their treatment of different lighting conditions, depending on the wildlife inhabiting the local environment [20].

There are other broad guidelines regarding light pollution, with a few Australian Standards (AS) referring to lighting, but those standards themselves are not laws. However, if state and Commonwealth (federal) laws require conforming to a standard, then that standard becomes mandatory in order to comply with that law [21]. In most cases, Australian state and federal laws do not require adhering to those Australian Standards that deal with lighting and/or light pollution. Consequently, local government policies that refer to the standards might be rare. However, this has not been previously examined in the literature.

In the USA, some local governments have taken responsibility for lighting cities, although their efforts to regulate the more intrusive forms of lighting at night have been sporadic and the substantial majority of local governments are silent about light pollution [20]. The lack of light pollution policy by local governments and cities is occurring despite model ordinances proposed by various bodies, including by the International Dark Sky Association (now Darksky International) developed with the Illuminating Engineering Society (e.g., [22]).

A key initial distinction in local governments developing lighting policy is that they have often used a system of zoning [18] or have reflected the policies of specific zones such as those enacted by broader levels of government. For example, the efforts of institutions focussing on broad issues such as astronomy have led some rural local governments to enact regulations specifically to protect areas for astronomical activity around the world, such as in the USA [20] and Australia (e.g., in the Warrumbungle area and others, as listed by the [23]).

The zoning approach to light pollution regulation is based on the belief that areas with different usage require different levels of lighting [13]. Zoning and other regulations in some cities have often focused on the historic role of ALAN to promote safety, navigation, advertising, and recreation, possibly with some restrictions to manage light spilling over property boundaries [20]. These categories of activities also give an indication as to which issues are important considerations in designing lighting policy.

2.1. Informing and Assessing Policy in Terms of Function, Technology, and Behaviour

Local governments tend to be inherently pragmatic, with consideration of long-term issues, while routinely tackling everyday problems [16]; thus, the issues reviewed below take a pragmatic approach. That is, from a pragmatic point of view, excluding issues associated with taking a strategic approach to sustainability, local governments could assess policies and interventions in terms of three main considerations: functionality, technology, and behaviours.

Lighting policies need to manage light pollution while also providing the intended services [10]. That functionality includes the costs of providing the service (especially financial, which will often line up with environmental impacts) and safety. Second, the characteristics of the technology being implemented need to be considered. Third, and perhaps the most surprising of these principles to be applied to policies such as light pollution, is that the impact of the behaviours that reflect the social usage of the relevant technologies can have negative consequences when the change was intended to make positive changes. All three of these principles are inter-related.

2.1.1. Functionality

Bear in mind that a key consideration is that light pollution is wasted light, light that is not functional, not providing a benefit—and it costs the city money. That is, the best approach for minimizing the impacts of light pollution is to not produce the excess light in the first place [10]. Further, because the costs of the production of light are a function of energy efficiency, then reducing costs will also reduce greenhouse gas emissions [18], but as noted above, emission reductions may not be a key focus where a local government is taking a pragmatic approach and is not necessarily attempting a strategic approach to sustainability. However, the importance of costs to a pragmatic approach reflects that the key driver of decisions to address light pollution, despite sustainability mandates aimed at reducing greenhouse gas emissions, is to save money by reducing costs [24]. Hence, it is the financial drivers that are most likely to spur action.

The second aspect of functionality is that of safety, both in terms of road safety and personal safety, often referred to in terms of crime. Motives and rationales for lighting regulations, when they exist, typically emphasise public safety, especially as work and leisure activities grew at night [20]. Underpinning the presence of light pollution is the belief that more light is better, particularly in terms of safety, whether for those driving on roads or the personal safety of those not on the roads. Yet, that belief has been repeatedly challenged across many studies (e.g., see examples at [25]).

Local governments seem keenly aware of road safety as a lighting concern, but have not factored in to their considerations that improvements in the headlights of cars and road design have reduced the levels of lighting needed for roads [24]. Similarly, although light levels may affect perceived safety [1], the associations between lighting and safety are not always as expected [26]. Assumptions that ALAN improves visibility and thus safety are often not true, with poorly designed lighting simply being light pollution, not safety-enhancing [5]. Indeed, early studies trying to link increased lighting with safety have been criticised substantially [27]. Recent studies confirm that brighter light is not necessarily associated with safety [26,28]. Indeed, the converse is often true—glare can create safety concerns, because if the eye has to adjust to brighter light levels, it may be unable to perceive potential threats [25].

At a macro level, studies using satellite data have also found no effects on crime when lighting levels were increased [10,29]. The pattern across studies appears to be that the effects of lighting on safety are non-linear, where lighting beyond a certain level has no effect on safety [1]. Efforts to assess what that level should be often defaulted to national standards, but were not necessarily based on any informed analysis [24]. In short, the misconception is that more lighting is safer, whereas the reality is that well designed lighting is safer [25].

2.1.2. Technology

Part of the effort to achieve well designed lighting relies on the use and nature of relevant technologies, the second main aspect of the pragmatic approach. Technological solutions to improve lighting outcomes and reduce light pollution include shielding, dimming, timers, controlling colour, and using more efficient luminaires [25]. That is, the use of smart technologies, such as computer-managed systems, may enable a more efficient and targeted way of providing public services, where the ability to dim or turn off streetlights may lead to substantially less energy being used [24]. Despite all of the technological solutions to light pollution and improved lighting outcomes being well established and extensively researched, many local governments seem to be either unaware of these technologies, or unwilling to implement them, possibly fearing the costs associated with transforming their lighting systems.

In addition, a cautionary tale about the choice of technology is that of light emitting diodes (LEDs). The adoption of LEDs for streetlighting has been driven by their energy efficiency and longevity, which can lead to substantial cost savings, along with reduced maintenance costs and enhanced adaptability by being more easily dimmed and controlled [20]. The potential for LEDs to save energy [18] is augmented by the array of tools such as software that can often double that energy saving [30].

A concern, though, is that LEDs, at least the initial waves of LEDs used, can create a spectral shift because they tended to emit more of the shorter, bluer, wavelengths in their white lights [2], which can increase light pollution and particularly affect human health [3], such as through suppressed melatonin levels. Furthermore, short wavelengths scatter more and thus disproportionally exacerbate skyglow [11].

Not only does the choice of technology need to include considerations such as colour, but the extended life of LEDs also increases the pressure to get the choice of technology correct, because the technology chosen may operate for a long time [24]. Thus, a more nuanced approach to the consideration of new technologies is needed, such as reducing the blue spectrum in streetlighting through the use of narrow spectrum amber LEDs or phosphor converted amber LEDs [20]. The desire to reduce the blue spectrum light emitted by LEDs is only the first, more technological, cautionary aspect of the use of LEDs. The second and more interesting aspect of the cautionary tale regarding LEDs is more about how the LEDs are used.

2.1.3. Behaviours

In practice, technologies are adopted in a social context where the actions and practices of local governments, as well as the behaviour of the people who install and/or interact with those technologies, need to be considered. Perhaps the classic case that highlights the need for the consideration of practices and social usage continues with the introduction of LED technology in street lighting.

The availability of more energy efficient luminaires has led to a phenomenon known as the ‘rebound effect’. The rebound effect is where rather than simply upgrading to more energy efficient products, local governments have increased the number of lights that are running, due to the lower cost per unit [31], a rebound that may be worse in higher income neighbourhoods [13].

For example, analyses in the UK have found that despite the increased energy efficiency of lighting over the past century, the rebound effect and consequent overlighting, led to an overall increase in energy use [4]. Evidently, without better design or policy that restricts light levels, the increasing energy efficiency of LEDs will be meaningless, and to improve policy, the actual and likely behaviours of the parties, including the local governments, which may increase the number of LED luminaires, need to be considered.

The direct impact of the rebound effect occurs because the new technology enabled paradoxical behaviour, where efforts toward sustainability and/or cost efficiency have led to the uptake of LEDs, and because the LEDs are so much more efficient, the local governments have introduced many more of them, thereby increasing the amount of light pollution. Yet the rebound effect arising from not having considered the behaviour of the local governments and populace may have consequences worse than increased light pollution due to indirect effects.

To better assess and inform lighting policy, the social use of lighting needs to be considered. Policy needs to consider both the likely behaviour of local government and the responses of individuals, such as increasing the number of LED luminaires to a level of overlighting. The need to socially inform regulations has been raised in other industries, including finance and fintech, where behaviourally informed regulation has been argued to be able to improve regulations (e.g., see [32]).

Assessing the efficacy of regulations should consider their limitations and how they will be implemented [33]. Focussing on the outcomes of regulations can identify issues that may suggest amendments that are needed [34]. Further, designing and assessing regulations should factor in behaviours, both in terms of how the involved organisations may act and the consumers’ behaviours in response to the regulations [35]. Expanding the consideration of regulation to include how organisations and people will respond leads to a behaviourally informed approach that may improve regulations.

More comprehensive forms of assessing policy consider materials and practices, along with combinations of actors and their inter-relationships, known as an assemblage [24]. Yet, the reality is often that reducing costs in the context of austerity politics is the key driver of lighting decisions [10]. Thus, considering the key criteria above—functionality, the technology, and the likely behaviour of local governments and people—presents a comprehensive, integrative approach to informing and assessing policy that may be a parsimonious form of assemblage and a stepping stone beyond focussing only on cost. Just as with assemblage, how the more parsimonious set of issues (functionality, technology and behaviour) comes together and how well they fit together is important.

Applying these criteria may result in some issues being universal, such as limits on total illumination per unit area, that all technology use shielding and reduce the presence of blue-violet wavelengths (applying [20]), but the details may need to be fine-tuned and adjusted over time. Fortunately, local governments have a relatively high degree of autonomy with urban infrastructure such as lighting [24], which allows them to conduct trials of combinations of functionality, technology, and behaviour as experiments. Local governments can then learn from trials across their and others’ cities, which may help to spread innovations.

Lighting policy can be informed by considering functionality in terms of costs, the nature of the technology, and the associated behaviours. Notably, a behaviourally informed approach to regulation considers the social use of technologies, not only how the populace uses the lighting but also the behaviour of the local governments and their cities.

In summary, light pollution can be reduced through more effective lighting design and better lighting policies. To understand the current state of lighting policy in Australia, particularly metropolitan greater Melbourne, in the state of Victoria, the extent of local, state and federal legislation and standards related to light pollution will be investigated. That current state of practice across metropolitan Melbourne will also be compared to international exemplars, leading to suggestions for improvements in lighting policy.

3. Materials and Methods

This study adopts a mixed methods approach to assess lighting policies in metropolitan Melbourne and overseas. First, the lighting policies of each local government (often known locally as councils) in metropolitan Melbourne were sourced and analysed. The websites, planning documents, and zoning codes for each council were identified and reviewed in June and July of 2024. Content was thematically coded based on relevant terms, measures, and parameters. Although the original intent of this part of the study had been to conduct a detailed coding of the nuances of each of these various documents in terms of their elements of lighting policy, very little lighting policy was found beyond that of the national guidelines and Australian Standards. The little lighting policy there was by local governments was classified into a hierarchy that delineated the key characteristics of the lighting policy at each level of classification (

Table 1. Categorization of the outdoor night lighting policies of Melbourne councils (as of July 2024).

Council	Classification
Kingston City	Has a specific lighting policy that explicitly addresses light pollution
Melbourne City
Bayside City
Stonnington City
Wyndham City	Has a specific lighting policy that acknowledges light pollution
Moreland City
Maroondah City
Hume City	Light pollution is acknowledged in other policies
Knox City
Whitehorse City
Monash City
Boroondara City	Has a specific lighting policy but does not acknowledge light pollution
Port Phillip City
Glen Eira City
Casey City
Nillumbik Shire	Lighting and light pollution are not specifically mentioned in any policies
Yarra City
Darebin City
Frankston City
Maribyrnong City
Brimbank City
Hobsons Bay City
Manningham City
Melton Shire
Banyule City
Greater Dandenong City
Moonee Valley City
Whittlesea City

). Of these, only four councils had explicit lighting policies that also addressed light pollution, and these were analysed in more depth.

Next, this study sourced and analysed Australian standards relevant to lighting. Australian standards were accessed through the Techstreet database. In Australia, the relevant standards are AS1158 for public spaces [36], AS1680 for interior and industrial lighting [37], AS2560 for sports complexes [38], and AS4282 for control of obstructive effects of outdoor lighting [39]. At a federal level, there is no mandated light pollution practice, but there are guidelines designed to protect wildlife from light pollution.

For both the lighting policy and Australian Standards data analyses, a document analysis was performed as the primary research approach. Document analysis is a well-developed and commonly applied research approach that is appropriate for extracting meaningful data and insights from data sources such as the policy documents studied here. For more background on the use of document analysis as a research method see [40].

Finally, this study sought case studies of international best practice in lighting and light pollution policy from the scientific literature. Specifically, this study adopted a narrative literature review approach, where studies similar in scope and intent to this study were sought, that is, studies that investigated lighting and light pollution policies for global cities. The search encompassed Scopus, Google Scholar, and Google, with key search terms including dark skies, light pollution, policy, regulation, and case study, with searches limited to sources published in the last 5 years. Only three such studies were found across all three platforms [20,41,42] that identified international examples of cities or regions that had adopted light pollution policies. Each of the cities and regions identified in these sources were analysed here.

4. Results

The first step in the analysis was to determine whether, and to what extent, the local governments in the greater Melbourne area had explicit lighting policies and whether those policies, if present, directly addressed or acknowledged light pollution. Only the cities of Melbourne, Bayside, Kingston, and Stonnington had specific lighting policies which explicitly addressed ways to combat light pollution. The cities of Maroondah, Merri-bek, and Wyndham had lighting policies which acknowledged (but did not address) light pollution. The cities of Hume, Knox, Monash, and Whitehorse acknowledged light pollution in other policies, but do not have specific lighting policies. The cities of Boroondara, Casey, Glen Eira, and Port Philip have specific lighting policies which do not acknowledge light pollution. The other 13 councils do not mention light or light pollution in any policies. The categories for each council can be found in Table 1.

Many of the councils, either explicitly or by omission, simply defer their lighting requirements to the Australian standards. For the purposes of this study, only the councils which explicitly address light pollution in their policies were examined further. These councils were Melbourne, Bayside, Kingston, and Stonnington. The cities with a light pollution policy are detailed in

Table 2. Classifications of councils with specific light pollution policies.

Council	Light Pollution Controls
Bayside City	Treats the entire council as an A0 environmental zone per AS4282 [39]
Melbourne City	Specifies fully cutoff light fixtures. All else per Australian standards
Kingston City	Per Australian standards
Stonnington City	Per Australian standards

. The Victorian Department of Transport and Planning also specifies some controls on digital outdoor signage, which are to be used in addition to AS4282.

Given that the main mechanism for executing lighting policy, by the few local governments with some specific lighting policy in greater Melbourne, referred to Australian Standards, the details of the relevant standards are reviewed. The Australian Standards pertaining to public lighting design are as follows: AS1158 Lighting for Roads and Public Spaces (Vehicular and Pedestrian), AS1680 Interior and Workplace Lighting, AS2560 Sports Lighting Specific Applications, and AS4282 Control of Obtrusive Effects of Outdoor Lighting. For the purposes of this study, only AS1158 and AS4282 will be considered, and their main characteristics with regards to light pollution are summarised in

Table 3. Light pollution controls in Australian Standards (AS).

Source	Controls for Light Trespass	Controls for Overlighting	Controls for Glare	Controls for Sky Glow
AS1158.1.1 Lighting for Roads and Public Spaces-Vehicular Traffic	Refer to AS4282	N/A	Includes adaptation distances for transitioning between different speeds	Maximum ULR 3% for conventional lamp, 1% for LED
AS1158.3 Lighting for Roads and Public Spaces-Pedestrian Area	Refer to AS4282	N/A	Limitations on luminous intensity (cd) depending on viewing angle and lamp height	ULR 4% (local roads traditional lamps), 1% (local roads LED), 5% (public areas traditional lamps), 3% (public areas LED) Fixtures with ULR > 40% are prohibited and ULR > 20% are discouraged
AS4282 Control of Obtrusive Effects of Outdoor Lighting	Maximum vertical illuminance, EV, for a property boundary or surface (lx): 0 (exclusion permitted for safety) (A0); 2 (A1); 5 (A2); 10 (A3); 25 (A4); no limit (TV)	Curfew default time 23:00–06:00 with 80% reduction in maximum illuminance Maximum vertical illuminance, EV for road and pedestrian lighting during curfew (see remarks) (lx): 4 (V); 1 (R1); 2 (R2); 4 (R3); 4 (RX)	To be reduced by design choices by “a competent lighting designer”	Prefers (does not mandate) CCT < 3000 K unless there is a safety reason to use 4000 K Maximum ULR: 0 (A0, A1); 1% (A2); 2% (A3); 3% (A4); 8% (TV)

Note: N/A = not applicable.

. AS2560 is out of scope due to its specificity, and AS1680 is out of scope because it does not address outdoor lighting, only indoor lighting. Most of the lighting standards came into effect in 1997 and have been revised over time (e.g., AS1158.1.1 came into effect in 1997, with the revised AS1158.3.1 coming into effect in 2020 and AS4282 originally came into effect in 1997, with the latest update released in November 2023).

The standards and later tables often refer to technical measurements that are briefly detailed here, but in themselves are not the focus of this study. To start, a luminaire is a lighting fixture made up of a light source, housing, optics, and shielding. The lay term of brightness is technically known as luminous flux, which indicates the total light emitted from a lighting source in all directions and is measured in SI units of lumens (lm). However, surface brightness (illuminance) is measured in terms of lux (lx), where one lux is equal to one lumen per square metre. Illumination levels range from around 1 millilux on a clear moonless light to 0.25 lux for a full moon, whereas road lighting is typically in the range of 5–30 lux [10].

There is also a parallel set of measures associated with lighting. For example, the luminous intensity refers to the light that shines in one direction and is indicated in terms of candela (cd), where relative to illuminance above, one candela equals 4π lumen. Similarly, luminance is an indication of surface brightness at a particular viewing angle and is measured in terms of cd/m² or nit [30]. For example, lighting levels that typically cause glare are on the order of 103 cd m⁻² for discomfort and 105 cd m⁻² for functional impairment [43].

The colours in visible light are characterised in terms of correlated colour temperature (CCT), which is measured in Kelvin (K). A light source with CCT around 2000–3000 K will appear warm (orange), around 5000 K will appear neutral white, and over 6500 K will appear cool (blue). Finally, one measure of a luminaire’s impact on sky glow is the upward light ratio (ULR).

Note that AS4282 does not apply to public lighting other than roads and pedestrian areas. There is no specified maximum vertical illuminance (the illuminance on the vertical face of a building or structure), EV, for road and pedestrian lighting outside curfew hours. For the standards, the relevant property boundary or surface is situational, although a maximum setback of 10 m and a measurement height of 1.5 m is specified if there is no structure closer to the boundary. Australian standards also provide environmental zoning in AS4282 as per

Table 4. Environmental zoning per AS4282.

Environmental Zone	Ambient Light Conditions	Description/Example
A0	Intrinsically dark	UNESCO starlight reserve IDA dark sky park, reserve, or sanctuary Major optical observatories Other accredited dark sky areas, e.g., areas of importance for astrotourism or wildlife protection Note: Some lighting may be required for safety
A1	Dark	Relatively uninhabited rural areas (terrestrial, marine, aquatic, coastal)
A2	Low district brightness	Sparsely inhabited rural and semi-rural areas where roadways are unlit (other than at intersections)
A3	Medium district brightness	Suburban areas in towns and cities where roadways are fully lit
A4	High district brightness	Town and city centres and commercial areas Residential areas near commercial areas Industrial and port areas Transport interchanges
TV	High district brightness	Vicinity of major sporting and event stadiums during TV broadcasts

Note that zones A0 and A1 typically have a minimum area of 50 ha (0.5 km²), although smaller environmentally sensitive areas may exist.

, and zoning categories based on road types are in

Table 5. Zoning for road and pedestrian lighting per AS4282.

Environmental Zone	Ambient Light Conditions	Description/Example
V	Traffic routes	Residences near major roadways near street lighting
R1	Local roads with significant setback	Residences near local roads where the window line is >10 m away from the property boundary
R2	Local roads	Residences near local roads where the window line is <10 m away from the property boundary
R3	Roundabouts or local area traffic management devices	Residences near roundabouts or local area traffic management devices where the window line is <10 m away from the property boundary
RX	Pedestrian crossings	Residences near pedestrian crossings where the window line is <10 m away from the property boundary

.

International Case Studies

Of the lighting policies of the 18 cities summarised in

Table 6. Light pollution controls in exemplar international cities/regions: Controls for light trespass.

Location	Controls for Light Trespass
Seoul, South Korea [41]	N/A
Beijing, China [41]	Light trespass should be considered in design phase Maximum surface brightness on windowsill of residential buildings and hospitals (lx): 10 (not adjacent to streets), 25 (adjacent to streets). After 23:00: 2 (not adjacent to streets), 5 (adjacent to streets) Maximum intensity for a luminaire in a window (cd): 2500 (not adjacent to streets), 7500 (adjacent to streets). After 23:00: 1000 (not adjacent to streets), 2500 (adjacent to streets)
Guangzhou, China [41]	Curfew on advertising lighting between 23:30 to 07:30 If floodlighting is used on residential buildings, it is to be shielded from windows
Shanghai, China [41]	Fixtures to be shielded or directed away from properties Maximum surface brightness on residential windowsill (lx): 2 (E1), 5 (E2), 10 (E3), 25 (E4). After 23:00: 0.5 (E1), 1 (E2), 5 (E3), 10 (E4) Maximum intensity luminaire in a window (cd): 2500 (E1), 7500 (E2), 10,000 (E3), 25,000 (E4). After 23:00: 10 (E1), 500 (E2), 1000 (E3), 2500 (E4) Floodlighting beyond or around the illuminated building not to exceed 25% of the fixture’s output Maximum surface brightness on a building (cd m−2): 0 (E1), 20 (E2), 60 (E3), 150 (E4) Advertisement signs maximum luminance (cd m−2): 800 (commercial centre), 600 (public area), 300 (residential area)
New York, NY, USA [20]	Lighting should be shielded off surrounding residential buildings, community facilities, and streets
Jacksonville, FL, USA [20]	Maximum illuminance at residential property boundaries 5.5 lux, non-residential property boundaries 11 lux
Chicago, IL, USA [20]	Parking garages and gas stations to shield their luminaires off adjacent property
Nashville-Davidson, TN, USA [20]	Luminaires to be directed off adjacent properties (does not require shielding) Maximum illuminance 5.5 lux across property boundary of a religious institution
Omaha, NE, USA [20]	Luminaires to be directed off adjacent properties (does not require shielding) Parking garages to have screens
Houston, TX, USA [20]	Luminaires in outdoor amusement areas should be shielded off residences Maximum illuminance 5.5 lux at property boundaries of cafes and vending machines
Seattle, WA, USA [20]	Luminaires to be shielded and directed off adjacent properties Lighting to be directed away from wetlands
Los Angeles, CA, USA [20]	Lighting to be shielded off residential properties Sports field light posts maximum height 75 feet and shielded off neighbouring properties Maximum illuminance 21 lx at residential property boundaries Maximum illumination from signs 32 lx at property boundary No more than 1 lux to escape 15 feet beyond property boundary
Flagstaff, AZ, USA [20]	Sign lighting to be fully shielded with no light directed beyond the sign (Zone 1)
Ringsaker, Norway [42]	Light is only permitted at the entrance to properties, not roads or carparks
Slovenia [42]	Maximum 10% of lighting of cultural monuments can fall beyond the monument itself
France [42]	Light trespass into residential buildings is prohibited
Belgium [42]	N/A

Note: N/A = not applicable.

,

Table 7. Light pollution controls in exemplar international cities/regions: Controls for overlighting.

Location	Controls for Overlighting
Seoul, South Korea [41]	Maximum illuminance 10 lux, 25 lux for industrial areas
Beijing, China [41]	Maximum surface brightness on a building (cd m−2): 10 (low light), 20 (moderate light), 45 (high light)
Guangzhou, China [41]	Curfew on public lighting between 22:00 and 06:00 Floodlighting on building facades is prohibited on public buildings
Shanghai, China [41]	Requires ratio of brightest to darkest spots to be less than 1:6 on lawns, gardens, and playgrounds Minimum illuminance (lx): 2 (lawns), 5 (gardens), 10 (playgrounds)
New York, NY, USA [20]	N/A
Jacksonville, FL, USA [20]	N/A
Chicago, IL, USA [20]	N/A
Nashville-Davidson, TN, USA [20]	Curfew on recreational areas such as ballparks and amphitheatres after 22:00 Lighting infrastructure to be appropriate for the current population density
Omaha, NE, USA [20]	Recreational fields curfew: 1 h after last event
Houston, TX, USA [20]	N/A
Seattle, WA, USA [20]	Artificial lighting should be avoided near shorelines where possible
Los Angeles, CA, USA [20]	Sports fields to have automatic timers
Flagstaff, AZ, USA [20]	Lamps more than 700 lumens prohibited in residential areas Curfew for businesses 30 min after close until open Curfew for sporting facilities 21:00 (Zone 1), 23:00 (Zone 2) Curfew for advertising signs 21:00 (Zone 1), 23:00 (Zone 2)
Ringsaker, Norway [42]	Lighting only turned on when property is in use Maximum 3 outdoor light sources per property Maximum 470 lumen fixture Light is only permitted at the entrance to properties, not roads or carparks
Slovenia [42]	Façade or cultural monument lighting maximum 1 cd m−2 Curfew on all non-safety lighting between sunset to sunrise Advertising curfew between 24:00 and 05:00
France [42]	Maximum 35 lux for suburban and 10 lux for rural areas for any installation Lighting of waterways at night is prohibited Curfews near astronomical sites
Belgium [42]	Dynamic freeway lighting which controls brightness in response to traffic

Note: N/A = not applicable.

,

Table 8. Light pollution controls in exemplar international cities/regions: controls for glare.

Location	Controls for Glare
Seoul, South Korea [41]	Advertisement signs maximum luminance (cd m−2): 50 (class 1), 400 (class 2), 800 (class 3), 900 (class 4 semi-industrial), 1000 (class 4 commercial) Decorative lighting maximum luminance (cd m−2): 20 (class 1), 60 (class 2), 180 (class 3), 240 (class 4 semi-industrial), 300 (class 4 commercial). Mean luminance (cd m−2): 5 (class 1), 5 (class 2), 15 (class 3), 20 (class 4 semi-industrial), 30 (class 4 commercial)
Beijing, China [41]	N/A
Guangzhou, China [41]	N/A
Shanghai, China [41]	Accent lighting of trees and water bodies should not produce glare Advertisement signs maximum luminance (cd m−2): 0 (E1), 200 (E2), 500 (E3), 1000 (E4) Illuminance of advertising signs at 1.5 m (lx): 1 (E1), 3 (E2), 8 (E3), 15 (E4)
New York, NY, USA [20]	N/A
Jacksonville, FL, USA [20]	Signs which flicker or are brighter than 40 lumens are prohibited
Chicago, IL, USA [20]	Signs within 200 feet of a roadway must not flicker or strobe
Nashville-Davidson, TN, USA [20]	Any signs that flicker or cause glare near any roadway are prohibited
Omaha, NE, USA [20]	Electronic signs should not flicker or cause glare. Maximum brightness 5200 cd m−2 during the day, 500 cd m−2 from dusk to dawn
Houston, TX, USA [20]	Attention-getting devices such as searchlights are illegal
Seattle, WA, USA [20]	Video signs, festoons, searchlights prohibited in most areas
Los Angeles, CA, USA [20]	Flashing or strobing signs prohibited Distracting lighting at public streets is prohibited
Flagstaff, AZ, USA [20]	Signs with flicker or motion prohibited
Ringsaker, Norway [42]	N/A
Slovenia [42]	Advertising signs can only be lit if the nearby area is brighter than 3 lx, and there are various light flux restrictions based on the size of the sign
France [42]	Use of searchlights, lasers and other beams is prohibited
Belgium [42]	LED billboards near traffic are regulated to reduce glare and improve safety

Note: N/A = not applicable.

and

Table 9. Light pollution controls in exemplar international cities/regions: controls for sky glow.

Location	Controls for Sky Glow
Seoul, South Korea [41]	N/A
Beijing, China [41]	N/A
Guangzhou, China [41]	Public and residential buildings to have surface reflectance less than 0.2
Shanghai, China [41]	Maximum ULOR: 1% (E1), 5% (E2), 10% (E3), 25% (E4)
New York, NY, USA [20]	Fully cutoff shielding (proposed), current 5% ULR and 80% of the light should fall below 80° Public lighting maximum CCT 3000 K
Jacksonville, FL, USA [20]	No light emitted above the horizontal plane near Outlying Fields
Chicago, IL, USA [20]	N/A
Nashville-Davidson, TN, USA [20]	N/A
Omaha, NE, USA [20]	Minimise adverse impacts on night sky views
Houston, TX, USA [20]	Highly reflective surfaces are prohibited
Seattle, WA, USA [20]	Future plans to restrict reflective materials
Los Angeles, CA, USA [20]	Exterior signs ULR < 5% Fully cutoff luminaires
Flagstaff, AZ, USA [20]	Fully cutoff fixtures required for lamps over 1750 lm, preferred for lamps under 1750 lm in industrial areas Maximum CCT 2700 K (C1), NSA LEDs required (C2), any fixture permitted (C3)
Ringsaker, Norway [42]	Maximum CCT 2700 K Fully cutoff luminaires
Slovenia [42]	ULOR 0%, can be a maximum 5% if lamps are <20 W. No ULOR limits for cultural monuments Beams directed towards the sky are prohibited
France [42]	Maximum CCT 3000 K, 2700 K for suburban areas, 2400 K for protected areas ULOR restrictions near astronomical sites
Belgium [42]	N/A

Note: N/A = not applicable.

, each addressed light pollution in varying ways. In a similar manner to most of the local governments in metropolitan Melbourne, Tianjin was the only international city reviewed with no specific measures in place whatsoever.

Most cities utilise environmental zoning to apply different lighting regulations based on the needs of the area. However, the definitions of each environmental zone, and the extent to which they are used in the regulations, vary significantly. Shanghai follows the CIE zoning recommendations as follows: E1, national parks and reserves; E2, suburbs and residential; E3, areas “outside the sub-centre of the city”; and E4, city centre and commercial. Guangzhou and Beijing separate zones into “low light” (residential and recreational areas), “moderate light” (public areas), and “high light” (urban and commercial centres) environments. Flagstaff employs two lighting zones which are dictated by proximity to the naval observatory.

Fifteen cities had controls in place for light trespass. Six cities specified maximum illuminance levels across property boundaries, nine cities required shielding or directing light away from neighbouring properties or roads, and four did both. The controls for light trespass in Beijing, Guangzhou, and Shanghai were the most prescriptive. They were also the only cities to specifically regulate the amount of light that can shine across a windowsill or through a window.

Of the 18 cities studied, 13 had controls in place for overlighting. Seoul, France, and Shanghai specified maximum surface brightness for various types of land use, ranging between 5 and 45 lx. Flagstaff extended this by specifying maximum light intensity density (lumens per acre). Beijing and Slovenia regulated the surface brightness on the walls of buildings. Six cities implemented various types of curfews, either between certain times or when areas were not in use. The dynamic freeway lighting in Belgium was also unique and notable.

Of the 13 jurisdictions which had measures in place for glare, 11 were to do with electronic signs. The exceptions were France and Houston, which do not restrict electronic signage, but do prohibit attention-getting devices such as searchlights and lasers. Seattle also had similar restrictions. Shanghai also specifies that decorative lighting of trees and waterways should not cause glare.

Eight of the 18 cities have controls in place for sky glow. These include minimising reflective surfaces and specifying fully cutoff fixtures. Additionally, Los Angeles required advertising signs to have a ULR < 5%. New York, Flagstaff, Ringsaker, and France were the only regions to control colour. New York specified a maximum colour temperature of 3000 K while Flagstaff, Ringsaker, and France specified a warmer maximum colour temperature of 2700 K. France additionally had the most restrictive control on colour, with a maximum CCT of 2400 K in environmentally protected areas.

Some regions had controls in place to address specific local issues. For example, Ringsaker has a high concentration of investment properties which are not always in use, and during these times lights are to be switched off. Similarly, in Slovenia lighting of cultural monuments is restricted to avoid light spill.

5. Discussion

Considering the elements of functionality, the nature of the technology, and likely behaviours, the lighting policies of the local governments of metropolitan greater Melbourne do not compare well. The City of Bayside was the only council to adapt the Australian environmental protection light pollution guidelines into their own policy. Twenty-one of the 28 councils in metropolitan Melbourne have not even acknowledged the existence of light pollution, let alone written specific policies to avoid it. The only council with a standalone document with light pollution regulations is the City of Melbourne. However, even that document does not build on the regulations in Australian standards. Beyond specifying fully cutoff luminaires and colour temperatures, the City of Melbourne’s policy does not specify any technical lighting parameters. Overall, even the councils with the “best” lighting policies in metropolitan Melbourne explicitly addressing light pollution simply defer to Australian Standards and those standards do not appear to be behaviourally informed, nor up to date with evidence.

The standard controlling obtrusive effects of outdoor lighting, AS4282, was overhauled in 2023. However, the Australian Standards focus more on specifying minimum, not maximum, lighting levels, which obstructs attempts to implement best practice lighting policy. That focus on having more light may reflect misconceptions about links between lighting and safety that need to be changed (e.g., per [26,28]).

5.1. Light Trespass

Light trespass seems to be a basic focus of lighting policy in the non-Australian exemplar cities. Most of the international cities implemented restrictions on the maximum surface brightness at a property boundary, although the limits varied between 0 and 25 lx depending on environmental zoning. Many cities in the US required the same limit of 5.5 lx at a residential property boundary, although Jacksonville allowed 11 lx for non-residential property boundaries. Los Angeles distinguished between illuminance from advertising signs, which can illuminate 32 lx at a property boundary, and allows 21 lx at a residential property boundary for ordinary luminaires. This is brighter than all similar restrictions. However, Los Angeles also specifies a buffer distance of 15 feet (4.5 m) over the property line where light must reduce to 1 lx. Flagstaff, often regarded as being a world leader in light pollution, does not specify any restrictions on light at a property boundary. In Australia, the upper limit for commercial areas is 25 lx at a property boundary while for the less inhabited A1 and A2 zones, this reduces to 2 and 5 lx. Those lighting levels place Australia in line with international practices, where the Australian Standards are mandated, in terms of light trespass. Yet, policy should proactively reduce light trespass levels rather than simply provide methods to measure it.

In technological terms, the simplest way to reduce light trespass is by designing lighting layouts that only direct light towards the areas that are intended to be lit, which would enhance their functionality and reduce costs. Such shielding can also be used to prevent glare [26]. Shielding can be particularly useful if the geometry of the lighting layout is such that light spill into unwanted areas cannot be avoided. Almost all the exemplars in the USA, as well as Guangzhou and Shanghai, require that lights are either directed away from properties or that shielding is used to prevent light spill on them. Australian standards do not directly specify this, as long as the minimum light trespass controls along the property boundary are met. Attempts are made to write requirements for shielding and direction of luminaires into some council policies such as the City of Melbourne. However, a more specific policy which mandates the use of shielding would be beneficial and a key step toward managing light pollution.

Given that light pollution is wasted light, light that is not functional, and costs the city money, the best approach for minimizing light pollution is to not produce the excess light in the first place [10]. Despite this, the likely reduced costs that would come from reducing light pollution was not an emphasis in any of the lighting policies from the local governments of greater Melbourne. Technological considerations, with some indirect consideration of functionality, appeared to receive the most attention, mostly because that is the emphasis of the current Australian Standards.

5.2. Overlighting

Overlighting can be avoided by using only the amount of light that is necessary for the task. This can be achieved in policy by a combination of specifying maximum light levels and involving curfews, timers, and sensors to dim lights when the area is not in use [8,25]. Some scientific reports neglect to include overlighting as one of the main types of light pollution. Not considering the importance of overlighting to light pollution may have led to incorporating maximum specified brightness levels in policy being overlooked in Australian policy.

AS4282 begins to address the problem of overlighting by introducing maximum surface brightness levels and controlling the amount of light spilling off the roadway onto adjacent areas. These quantitative controls against overlighting specify maximum light levels for road and pedestrian areas during curfew hours. Furthermore, during curfew hours, the light across a property is to be reduced by at least 80% of maximum permissible values. Yet, while AS4282 is a step in the right direction for dark skies in Australia, it does not solve many of the problems pertaining to light pollution. Depending on the road and pedestrian zone type, the maximum permissible surface brightness ranges from 1 to 4 lx. Those levels are quite restrictive, as they should be, given that road lighting is one of the key contributors to light pollution [2] and is an improvement on the focus on minimum lighting levels in previous regulatory supports. However, it is important to note that those restrictions only apply to road and pedestrian lighting. More needs to be done to ensure that residential and commercial areas are also not over lit. Simply dimming the light near the property boundary while keeping the main lighting at the regular intensity would be compliant but undesirable. Furthermore, when interpreting the pedestrian and road lighting zones in AS4282, a kind of “rebound effect” should be avoided. There is a concern that the standard could be interpreted as mandating a certain light level for those types of roads. Rather, the intention of the standard should be that if lighting is deemed necessary, then controls should be put in place. Applying the basics of functionality suggests that the preference should always be to begin with darkness first and then add the minimum light that is necessary for the task.

Only three of the international exemplars studied in this case specified maximum surface brightness for any areas. These were Seoul, Shanghai, and France. Maximum brightness ranged significantly depending on land use: from 2 to 5 lx for parks and gardens in Shanghai; 10 lx for residential areas in Seoul and rural areas in France; 25 lx for industrial areas in Seoul; and 35 lx for industrial areas in France.

In general, the Australian standards were comparable in many respects with the international exemplars in engaging overlighting in terms of functional and technical specifications. The specification of maximum lux levels across a property boundary are a step in the right direction, as are the use of timers for facilities such as sports fields. Yet there are other areas where the Australian Standards could be improved.

5.3. Sky Glow

Light that is directed above the horizontal plane (indicated by the ULR), which directly causes skyglow, is restricted in the Australian standards, with different values of ULR for different environmental zones with maximum permissible ULR ranging from 0 to 8%. Exemplars such as New York and Los Angeles required fully cutoff shielding, meaning no light is directed upward from the luminaire, in all applications. Requiring full shielding is the most impactful restriction on sky glow. However, given that sky glow is a culmination of all light directed upwards, it is necessary to reduce the number of contributing luminaires appropriately in all zones (applying [13]), which would be a good addition to the Australian Standards.

Whether the ULR levels in the Australian Standards will notably impact well-lit, reflective commercial areas remains to be seen. The need for ULR to always be set to zero, even in commercial areas, is particularly important because commercial areas are often the brightest areas and thus the largest contributors to sky glow [2]. Considering technology and behaviour may help. The use of sensors to decrease the light intensity when the area is not in use potentially helps to reduce sky glow [26].

A more behaviourally oriented tool that was used to manage lighting in some of the non-Australian exemplars was the use of curfews. Some curfew periods are specific to the land use activity. For example, Omaha, Flagstaff, and Los Angeles require sports fields to turn lights off when not in use. The most interesting application of sensors and timers is in Belgium, where freeway lighting is dynamic and can dim in response to traffic levels. Some regions specify a maximum luminous intensity for light fixtures. Arizona goes a step further and prescribes maximum “luminous intensity density” or fixtures per acre. However, these controls are less effective as the figure of luminous intensity is relative to the situation. A floodlight, for example, will tend to have a higher luminous intensity, but because the light is spread out over a larger area, the optics and positioning of the luminaire could lead to a lower surface brightness than if many fixtures of a lower intensity were used. In short, it is prudent to specify maximum surface brightness and allow lighting designers to adapt the system to meet that criterion using a wider choice of luminaires.

5.4. Glare

There is also room for improvement for the light pollution issues of glare and colour in the Australian Standards and thereby the few lighting policies of the local governments of greater Melbourne that went as far as referencing those standards. For example, the qualitative controls for glare could have included more on avoiding flickering or strobing displays. Some international regions prohibit attention-getting devices such as lasers, searchlights, and beam lights. In Australia, these are regulated by the Civil Aviation Safety Authority. Seattle also prohibits festoon lights, although festoons are comparatively low-risk luminaires. A simple solution to glare involves qualitatively specifying luminaires that are fit-for-purpose, only lighting the intended area and at the appropriate intensity. Giving primacy to the functionality of lighting design is a key approach to implementing appropriate controls that could address more than one type of light pollution, such as overlighting and glare, simultaneously.

Policymakers should extend the scope of AS4282. Currently, the standard only applies to road and pedestrian areas, but it should be expanded to include further public lighting installations such as outdoor malls, parks, and recreational areas. The 20 km rule for wildlife protection in National Light Pollution Guidelines should also be increased, given that the effects of sky glow can be seen at much greater distances. Policy should also be expanded to include more specific benchmarks for light pollution, such as mandating the use of shielding and directing light only toward the area of interest; specifying fully cutoff luminaires (ULR 0%) in all environmental zones, especially in commercial areas which are the brightest and hence contribute the most to sky glow; expanding the requirements for sensors and timers; and specifying warm colour temperatures, ideally less than or equal to 2700 K.

In terms of colour control, AS4282 currently prefers, but does not mandate, CCT 3000 K luminaires, and allows for bluer colour temperatures of 4000 K if there is a safety reason to do so. The lack of controls on blue light appears to be a missed opportunity to eliminate short wavelength light from roads and public lighting because it is likely that lighting installations will continue to use 4000 K luminaires until forced to do so. For the international exemplars reviewed, only New York, Flagstaff, Ringsaker, and France specify maximum colour temperatures. The limits are mostly 2700 and 3000 K, although France requires even warmer luminaires at 2400 K for protected environmental zones. Another emerging technology is narrow-spectrum amber LEDs, which were specified only in Flagstaff. Policymakers are advised to consider specifying narrow-spectrum amber LED technology (per [20]), especially in areas where wildlife may be particularly vulnerable.

5.5. Functionality, Technology and Behaviour

A key aspect of the exemplars included in this study is that those that are local government-focused have driven their lightning policies on their own initiative, without state or federal regulations or standards that require such solutions. This suggests that the Australian local government areas investigated in this study could also choose to improve their ambition with respect to light pollution, despite the fact that they are not required to do so by Australian state or federal legislation, and irrespective of the fact that the Australian Standards that deal with lighting and light pollution are not very ambitious. To take such initiative, however, requires drivers beyond those that local governments seem to be responding to, and we argue that the pragmatic approach offers such a driver.

More broadly though, beyond the specific parameters that may be included in lighting policies, whether the policy is created and implemented at all will still often come down to cost savings (per [24]). A pragmatic approach to lighting policy acknowledges that a key focus is on reducing costs and those cost reductions can be obtained by lighting design that considers the inter-related principles of functionality, technology, and behaviour. The combination of these issues can also be applied to future issues. For example, the behaviours associated with LEDs that led to the rebound effect could require better lighting design with the use of power factor varying technology. But how should local governments respond if other future technologies are widely introduced?

What if there was interest in a city in suggestions such as the use of the free capacity of the power systems of street lighting during the day for something like (e.g., see [30]) widespread electric vehicle charging? There would probably need to be pre-conditions before that situation arose, such as widespread electric vehicle uptake and the dominant power generators being renewable, but how should a local government react and what policies could it implement if presented with that suggestion? The potential policies in that situation could be designed and interrogated by considering the functionality of the systems, a broader array of issues associated with the technology, and the likely behaviour of the city and the populace.

More broadly, the relatively high degree of autonomy held by local governments for such policies [24] would mean that that city’s response would be a trial that other cities may learn from, which would help to spread innovations. Explicitly considering the likely behaviour of the parties involved should help accelerate the learning of local governments both before a policy is introduced and afterward, when the policy is being learnt from.

6. Conclusions

Cities and local governments are charged with providing the services desired by their populace. At the same time, the lived infrastructure of local governments that serves the populace, such as lighting policy, often comes down to reducing costs, within the options presented by the available technology [24]. Some local governments are taking a strategic approach to sustainability and face a range of challenges in attempting such transformative change [15]. For those local governments not taking a strategic approach to sustainability, there are a lot of changes local governments can make without substantial changes to their strategy and culture and without embracing a sustainability ideology, and addressing light pollution is a good example for demonstrating how such a policy could be considered.

Considering a relatively parsimonious set of issues in developing policy for lived infrastructure such as lighting enables the assessment of combinations of issues without becoming too complex. The combinations of the issues of functionality, technology, and behaviour are a comprehensive set of characteristics to use for informing and assessing policy.

Although cost is often used as they key criterion, much of the attention in the consideration and design of lighting policy focuses on the options presented by technology. Spectrum-controlled LEDs, in combination with computer-managed control systems (e.g., for dimming), present energy efficient (and cost effective) options for streetlighting. But to avoid phenomena such as the rebound effect, the likely behaviours of local governments and people need to also be considered.

The consideration of likely behaviours is perhaps the most interesting of the suggested key criteria. Policies can be improved by considering behaviours, both in terms of how the involved organisations may act and the consumers’ likely behaviours in response to the policy [35]. The consideration of behaviours may help to avoid or ameliorate rebounds in energy use and can work in combination with the other key criteria to improve policy.

There are many ways the key issues combine. Basic technology such as shielding directly reduces the amount of light that could become light pollution but also improves functionality in terms of personal safety by reducing the effects of glare (e.g., see [22]). Technology such as spectrum-delimited LEDs with dimming controls and power factor compensation can be more effectively utilised such as with situation-customised dimming (e.g., when the area is not in use). Yet, beyond these simpler applications of the key criteria, the real value of the use of these criteria, especially for pragmatic local governments, is their application to future situations.

Benefits could also be seen through a more considered focus on light pollution that adopts a range of specific policy objectives that can demonstrably reduce light pollution. These include specifying luminaires that are fit for purpose in different applications, mandating shielding, directing light towards areas of interest, restricting most lighting applications to warm colours (below 2700 K), and extending existing policies to cover a wider array of public lighting.

Future challenges for the lived infrastructure of cities, using the available power from current lighting systems as an example, include the impacts of electric vehicles and the resolution of potential contradictions, such as (from [10]) the use of dark-coloured surfaces to reduce reflectance, apparently contradicting the calls for lighter-coloured roofing and pavement to reduce urban heating effects. There will also be many other technologies in the future that will need assessment for the policy of local governments. The assessment and improvement of future policies will be facilitated by cities learning from each other when they conduct trials.

Even if a local government is not adopting a strategic approach to sustainability, policies that reduce light pollution, with controls to avoid behavioural complications such as rebound effects, should reduce costs for the local governments and reduce greenhouse gas emissions. A pragmatic focus on being able to provide the desired services, while maintaining costs, given the technologies available and the likely behaviours of the city and its people, provides a powerful, parsimonious approach to informing policy.