Light pollution: the rules to know for your site
The outdoor lighting of a commercial building is governed by switch-off times, a colour temperature limit and a ceiling on flux emitted towards the sky. Here is what the site manager must check and how the choice of luminaire makes compliance easier.
5 min read
A local resident writes to the town hall: the floodlight in the neighbouring company's car park lights up their bedroom all night. On this occasion, the site manager discovers that its outdoor lighting falls under a specific text and that the complaint is well founded. The subject is better dealt with before the letter than after.
The French regulatory framework for night-time lighting
The prevention of light pollution is set out in the French Environmental Code, in articles L583-1 et seq. The implementing text is the order of 27 December 2018 on the prevention, reduction and limitation of light pollution. It covers the outdoor lighting of non-residential buildings, car parks, outdoor construction sites, heritage lighting and the lighting of parks and gardens.
The order acts on three levers: switch-off times, a colour temperature limit and a ceiling on the flux emitted above the horizontal. These three points can be checked on a data sheet and on a clock, without any measuring instrument and without a design office.
Enforcement is the responsibility of the mayor and the prefect. A formal notice requires the installation to be brought into compliance, which may mean changing an orientation, changing a shade or replacing entire luminaires.
Shop windows, signs, façades: who is concerned
The regimes overlap, which explains much of the confusion on the ground. Façade lighting, shop window lighting and the indoor lighting of business premises fall under the 2018 order. Illuminated signs fall under the national advertising regulations, also in the Environmental Code, with their own times.
The same shopfront can therefore combine three distinct obligations: the window, the sign and the façade lighting. Each has its own schedule, and nothing requires them to coincide, unless you want to simplify the programming of the control panel.
Business buildings are concerned in the same way as shops. A lit-up commercial headquarters, an employee car park or a logistics area lit all night fall within the scope of the text.
Switch-off times and exceptions
| Installation | Switch-off | Switch-on |
| --- | --- | --- |
| Indoor lighting of business premises | at the latest one hour after occupancy ends | at the earliest one hour before occupancy begins |
| Lighting of building façades | at the latest at 1 am | at the earliest at sunset |
| Shop windows | at the latest at 1 am, or one hour after occupancy ends | from 7 am, or one hour before activity begins |
| Uncovered car parks | at the latest two hours after occupancy ends | at the earliest one hour before occupancy begins |
| Illuminated signs | between 1 am and 6 am | outside this period, unless there are local regulations |
Exceptions exist: the eves of public holidays, locally defined festive periods, authorised exceptional events, sites with continuous activity. Lighting strictly necessary for the safety of people and the surveillance of premises is dealt with separately, but it does not justify leaving an entire car park lit at nominal level all night.
Flux directed towards the sky and floodlight orientation
The share of flux emitted above the horizontal distinguishes a luminaire designed for outdoor use from a floodlight mounted at an angle. It is capped by the order, with a stricter threshold outside built-up areas and in protected areas. It is read on the data sheet, provided the luminaire is actually installed flat.
A floodlight tilted upwards sends part of its flux directly into the sky, whatever the quality of its optic. The practical rule fits in one sentence: you light a surface, not a volume. Outdoor and road lighting luminaires are designed for horizontal installation and a distribution directed towards the ground.
For lighting a building, downward lighting from a bracket or a canopy complies with the text better than a ground-mounted floodlight aimed upwards. When the latter remains essential, the beam must be contained by the façade itself, with anti-spill accessories and precise aiming at installation.
Colour temperature and protection of biodiversity
The order caps the colour temperature of outdoor installations at 3000 K in mainland France. The threshold drops to 2700 K around astronomical observation sites and to 2400 K in protected natural areas.
The logic is ecological: the blue component disrupts the orientation of insects, bats and migrating birds, and alters the cycles of vegetation close to light points. The limit applies whatever the type of luminaire.
It is checked at the order stage, not at handover. An outdoor luminaire at 4000 K, very common in general catalogues, is not suitable. The shade must appear explicitly on the purchase order and in the as-built file.
Choosing a luminaire that limits intrusive light
Intrusive light is light that leaves the area to be lit and enters the neighbour's property. It is combated through the optic and the layout, not through power.
- An asymmetric distribution makes it possible to bring the light right up to the property boundary without crossing it.
- Visors, barn doors and anti-glare louvres cut the beam in the troublesome direction only.
- A closer, lower light point creates less spill than a single very tall mast responsible for covering everything.
- An accent luminaire with a narrow beam lights the architectural feature without spilling around it: see the outdoor architectural lighting solutions.
Controls complement the optic. Reducing power in the middle of the night and detection in little-used areas reduce the nuisance and the consumption, without removing the lighting useful to the people present.
Evidence to keep in case of inspection
The inspection covers the installation, but the discussion relies on documents. An up-to-date file avoids having to demonstrate compliance luminaire by luminaire, ladder in hand.
- The data sheets of the luminaires installed, with colour temperature and photometric distribution.
- The layout plan, with the orientations chosen and the mounting heights.
- The programming of the timers and circuits, dated and signed.
- The handover report and any measurements carried out.
- A record of complaints received and the action taken on them.
On a site that is already equipped, a compliance check of the lighting installation identifies the points to be reworked, and an audit of the existing lighting costs the replacements to be planned.
Schedule a night-time survey from the property boundaries, camera in hand, before placing any order.
Then select luminaires designed for outdoor installation in the outdoor lighting category.
Further reading: Façade lighting: techniques, IP/IK ratings and compliance with light pollution rules and Renovating public lighting: what a municipality must check. Reference: French order of 27 December 2018 on light pollution (Ministry for Ecological Transition, in French).
In the Rexylum catalogue: REXPACK-300 · High-Performance Wall Pack and the Car parks range. To size the installation: the photometric study by Luminance Consulting.
