Renovating outdoor lighting: applications of the « light pollution » decree

October 2021

Agence pour l’Environnement et la Maîtrise de l’Energie (ADEME)

The subject of many economic, political and environmental issues, outdoor lighting, and in particular its management in public spaces, now appears to be a competence in its own right. For the past fifteen years, the price of electricity has been rising steadily, putting a strain on local authorities’ budgets, which amount to 1 billion euros per year in France. With an ageing and energy-intensive lighting stock, the territories have been addressing the issue for several years in order to limit consumption and therefore energy expenditure. Some have implemented coherent and ambitious renovation programmes on their own or on an inter-municipal scale. Despite the 500 million euros of annual investments made by local authorities to renew and modernise their public lighting systems, consumption remains high and the efforts made must be increased. Public lighting is now at the heart of the expectations of citizens, who are increasingly concerned about the way in which the city is administered, but also increasingly involved in environmental protection. Public lighting is a source of light pollution that contributes to the fragmentation of natural habitats. Intelligent management of lighting is therefore essential. The technological tools for this management already exist.

In addition, new needs are emerging in our territories: video protection, wifi terminals, electric vehicle charging stations, etc. Lighting infrastructures are increasingly in demand and should eventually become one of the means of pooling equipment for these new needs.

This is why it is becoming urgent to accelerate the renovation of the network and to make it communicative with a view to the development and planning of future intelligent territories. Public lighting is one of the major players in the ecological transition and a lever for action to limit light pollution and energy consumption. This guide published by ADEME should enable readers to gain a better understanding of the public lighting stock, to better grasp the issues at stake and to become players in its transformation.

To download : ademe-eclairage-exterieur-2021.pdf (3.9 MiB)

The Order of 27 December 2018 is the first specific regulation on artificial light emissions from outdoor lighting installations. The latter, as well as those of indoor lighting voluntarily emitted to the outside, must now be designed in such a way as to prevent, limit and reduce light nuisance, in particular excessive disturbance to people, fauna, flora or ecosystems, but also energy waste and obstacles to the observation of the night sky. Please note: the decree distinguishes between different categories of lighting installations, each with its own specific requirements. There are also some common requirements, as described below. Automatic presence detection and natural light control systems can be used to override any switching-on and switching-off requirements of the decree. If necessary, the managers of lighting installations should discuss the possibility of switching off with the parties concerned. Lighting whose function is mainly to ensure safety or security on a pathway but whose luminous flux does not ensure visibility for traffic is excluded from the scope of the order. Installations with a unit luminous flux of less than 100 lumens are considered to be lighting devices.

Because of the mandatory application of the order, its requirements take precedence over certain provisions of standard NF EN 13201. On the other hand, for the lighting of pathways in ERP (establishments open to the public) and IOP (installations open to the public), the requirements of the decree of 20 April 2017, relating to the accessibility of people with disabilities, take precedence over those of the luminous pollution decree. The requirement is therefore 20 lux on average. Lighting installations must not emit excessive intrusive light in dwellings (particularly disturbing for sleep), whatever the source of this light (public or private lighting, shop windows, illuminated signs, etc., except for event lighting). Direct lighting of water surfaces is prohibited.

A. Lighting for traffic and roads

This refers to exterior lighting intended to promote the safety of movement, people and property and the comfort of users in public or private spaces, in particular roads. This does not include lighting integrated into vehicles, tunnel lighting or lighting installations designed to ensure aeronautical, rail, maritime or river safety. There is no time requirement (on/off) for public lighting. Only lighting installations located in a zone of economic activity, delimited by a physical barrier, are switched off at the latest one hour after the activity has ceased and are switched on again at 7 a.m. at the earliest or one hour before the activity starts if it is carried out earlier. For these installations, when the luminaires are controlled by presence detection systems, it is permitted to light for the time of the passage of persons. This derogation is only tolerated for occasional lighting, i.e. if the device also allows for switching off shortly after the passage of people.

It is for this category, as well as for car parks, that the decree sets requirements for the nominal ULR (upward light ratio: percentage of flux emitted above the horizontal) of luminaires: less than 1%. The lighting installation complies with the mounting conditions recommended by the manufacturer and has a ULR of less than 4%. Luminaires in this category with a ULR greater than 50% must be replaced by January 2025. Stylish lanterns, which reproduce « a model present before 1945 and has been reconstructed from archives [or] is protected as a historic monument or by the regulations of a heritage site [or] is integrated into a protected building or complex » are exempt from the ULR requirements until 31.12.2023. CIE flux code 3 is greater than or equal to 95%. The colour temperature does not exceed 3000 K (several types of sources offer colour temperatures from 1800 K).

The DSFLI must not exceed 35 lm/m² in built-up areas and 25 lm/m² outside built-up areas.

a) the changing road environment

For the last 50 years, the car was the main means of transport in the city. Today, the trend, especially in cities, is for urbanisation to be more cyclist and pedestrian oriented. Lighting is following this trend with purpose-built luminaires placed at a lower height (5 or 6 m). Pavements are dimmed, except in pedestrian crossing areas or where there is interaction with cycle paths. The CRI is a decisive criterion for the quality of the environment for pedestrians and soft transport. Another notable change is that trees have regained their place in the city, with cast shadows and seasonality creating a new way of lighting in volume.

b) Visual comfort

Given these new habits, in particular the lower light heights, glare control has become essential. In order to improve the visual comfort of users, designers are increasingly using accessories such as louvres, low luminance optics and prismatic filters, which were previously used mainly for lighting in buildings. As for the CRI, a minimum of 80 is appropriate in convivial areas.

B. Lighting of heritage, parks and gardens

This concerns the lighting of heritage, i.e. all property, real or personal, belonging to the public or private sector, which is of historical, artistic, archaeological, aesthetic, scientific or technical interest. The perimeter taken into account to enter this framework is defined by the various classifications under the Heritage Code, such as the classification as a historical monument. This chapter also covers the lighting of buildings, as well as private and public parks and gardens accessible to the public or belonging to companies, social landlords or co-ownerships. Lighting is switched on at sunset at the earliest and switched off at 1 a.m. at the latest. Only for parks and gardens are there requirements for the DSFLI: it must not exceed 25 lm/m² in built-up areas and 10 lm/m² outside built-up areas. There are no requirements for other buildings or spaces in this category.

a) Heritage lighting

Architectural lighting has also evolved towards much lower wattages, thanks to new technologies that allow better control of the balance of contrasts, moving towards greater sobriety and leaving aside the large 400 W projectors in favour of miniaturised luminaires. It has thus become easy to reveal the architectural details of façades by placing the luminaires on them without them being directly visible to users. In addition, the lighting is less low-angle and more high-angle, which limits the flow towards the sky.

Colour can also be used more easily without overpowering the building, offering a variety of dynamic lighting possibilities, and also opening up the artistic field through dimming. These tools make it possible to implement several intentions that show other facets of the monuments, at reasonable costs. The work of lighting design is increasingly similar to drawing via video and mapping.

b) parks and gardens

In these areas, the trend is somewhat reversed, as the colour blue should be avoided as it is very disturbing for nocturnal animals. Thanks to the technologies and systems available, it is possible to combine beauty and sobriety without falling into an overly functionalist approach or seeking museum-like performance in public spaces. The emphasis should be on presence detection and appropriate lighting, limiting it to a few pedestrian traffic zones.

C. Sports facilities

This field includes open-air sports facilities or those that can be opened up (stadiums with adjustable roofs). Although the decree does not set out specific obligations for sports facilities as such, car parks attached to sports facilities must comply with the obligations applicable to car parks and detailed below (see paragraph E: Car parks).

D. Non-residential buildings

This refers to the external illumination and internal lighting of these buildings (excluding toll plazas). Lighting installations for access roads to these buildings must comply with the requirements for travel lighting (see p.14). The colour temperature of outdoor illuminations and indoor lighting deliberately emitted to the outside does not exceed 3000 K. For the illumination of buildings, the IFLR should not exceed 25 lm/m² in built-up areas and 20 lm/m² outside built-up areas.

In the case of facades, the vertical surface illuminated must be considered. The interior lighting of premises must be switched off one hour after the end of the activity. Window lighting in shops and exhibitions may be left on until 1 a.m. and must be switched off one hour after the end of the activity. They may be switched on again one hour before the start of business in the morning.

These time requirements are normally met in the case of the majority of buildings whose lighting has been renovated since January 2018, as the Order of 3 May 2007, amended in March 2017, requires, during these renovations, the implementation of automatic devices allowing the lighting to be lowered or switched off if the premises are unoccupied, combined with automatic dimming of the artificial lighting according to the amount of daylight.

E. Car parks

This refers to the lighting of uncovered or semi-covered, private or public car parks. Lighting whose function is mainly to ensure safety or security on a pathway but whose luminous flux does not ensure visibility for traffic is excluded from the scope of the Order.

Installations with a unit luminous flux of less than 100 lumens are considered to be lighting devices. There is no requirement to switch on and off for public car parks. On the other hand, the lighting installations of car parks in an economic activity zone are switched on at sunset at the earliest and are switched off two hours after the end of the activity. These lights may be switched on again at 7 a.m. at the earliest or one hour before the start of the activity if the activity takes place earlier.

However, when the lighting installations are coupled with detection devices, the decree allows these installations to light for the time that people are passing. This derogation is only tolerated for occasional lighting, i.e. if the device also allows the lighting to be switched off shortly after the passage of people. The nominal ULR of the luminaires is less than 1%. The lighting installation complies with the installation conditions recommended by the manufacturer and ensures a ULR of less than 4%. As for travel lighting, style lanterns are exempt from ULR requirements until 31 December 2023, and luminaires with an ULR of more than 50% are replaced before January 2025. CIE flux code 3 is greater than or equal to 95%. The colour temperature does not exceed 3000 K. The DSFLI must not exceed 25 lm/m² in built-up areas and 20 lm/m² outside built-up areas. For semi-covered car parks, the ULR, colour temperature, CIE flux code and DSFLI requirements only apply to the uncovered levels of the building. Covered levels must comply with the requirements for non-residential buildings.

F. Event

Outdoor events are temporary light installations used for artistic, cultural, commercial, sports or leisure events. Given the ephemeral nature of events, there are no temporal conditions or technical requirements, with the exception of the ban on intrusive light in dwellings. There is no limitation on colour temperature.

G. Building sites

The requirements for construction sites are as follows: lighting on at sunset at the earliest; lighting off at the latest one hour after the end of the activity.

H. Protected areas

In these areas (nature reserves, national parks, natural parks, astronomical observation sites), the prefect may reinforce the requirements by setting more restrictive obligations, both in terms of timing and technical requirements, after consulting the parties concerned. Within the perimeter of the national parks, the maximum colour temperatures for lighting are 2,700 K in built-up areas and 2,400 K outside built-up areas. The 56 territories labelled « Regional Nature Parks » are home to numerous plant and animal species (the National Inventory of Natural Heritage mentions approximately 183,000 species present in France) and are intended to support the economic and social development of the territory, while preserving and enhancing the natural, cultural and landscape heritage. In particular, they ensure that light pollution is limited. Some of them have been awarded the « International Dark Sky Reserve » (IDSR) label by the International Dark Sky Association (IDA).

There are three RICEs in France:

Within the perimeter of the astronomical observation sites, the DSFLI technical prescriptions, defined for the zone outside the urban area, apply. The nature parks help municipalities to reduce light pollution by assisting them in renovating their public lighting: for example, via conferences to explain the standards and regulations (decree of 27 December 2018 in particular) and the rules of the art (avoiding light halo, defining colour temperature, glare, etc.), and via night-time outings that allow the discovery of existing fauna and flora. In association with other actors, within the framework of a multidisciplinary approach, they can accompany the renovation of public lighting, explain the lighting project and advise them on finding the necessary financing.


To go further

bibliography (french)

  • Dépenses énergétiques des collectivités locales, ADEME, Caisse des Dépôts, FNCCR, AITF, CEP. 2019.

  • Guide de l’élu local et intercommunal. Éclairage public. FNCCR. 2021.

  • Publications de l’Association française de l’éclairage relatives à l’éclairage extérieur.

  • Trame noire - Méthodes d’élaboration et outils pour sa mise en œuvre, par Romain Sordello, Fabien Paquier et Aurélien Daloz. Publié par l’Office français de la biodiversité, mars 2021.

  • Annexe SSL : Solid State Lighting, Association internationale de l’énergie.

  • Les défis de l’éclairage public, par Roger Narboni, Concepto, et Fanny Guerard, responsable éclairage public, smart city et environnement, ville d’Asnières-sur-Seine. Territorial Éditions. 2021.