Façade lighting: techniques and standards

Lighting a façade is a balancing act between aesthetics, technical performance and regulatory compliance. Done well, it reveals the architecture without dazzling or wasting energy. This article details the main façade lighting techniques, the ingress protection ratings to be respected outdoors and the obligations arising from the French order of 27 December 2018 on light pollution.

Lighting techniques

Each façade calls for an approach according to its material, its reliefs and the effect sought. Four techniques make up the lighting designer's toolbox.

Grazing light (wall grazing)

The luminaire is placed very close to the wall, at the foot or top of the façade, so that the light skims it at an acute angle. Reliefs are heightened and shadows marked: it is the ideal technique for dressed stone, brick, textured concrete or mouldings. Grazing enhances the material rather than the surface.

Uniform wall washing

Conversely, the luminaire is moved away from the wall to spread the light in a soft, even gradient, from top to bottom. Wall washing erases surface defects and suits flat façades that are to be displayed as a regular luminous background, without hot spots.

Backlighting (silhouetting)

By lighting the background rather than the object, the silhouette of an element is drawn like a shadow puppet: colonnade, ironwork, vegetation. Backlighting creates depth and mystery, and works very well on openwork elements.

Spot lighting (accent)

A directed beam isolates a precise detail · porch, sculpture, sign, remarkable balcony. Spot lighting establishes a hierarchy in the reading of the façade and focuses attention on its strong points.

These techniques are readily combined on the same building. For an overview of the architectural approach and dynamic control, see our article on architectural building lighting.

Withstanding the outdoors: IP and IK ratings

A façade luminaire is subjected to rain, dust, temperature variations and, sometimes, impacts or vandalism. Two standardised ratings qualify its robustness:

The IP rating (Ingress Protection): two digits describing protection against solid bodies (1st digit) and water (2nd digit). For an exposed façade, IP65 (dust-tight, protected against water jets) is a minimum; IP66 reinforces protection against powerful water jets from all directions, recommended on very exposed sites.
The IK rating: it quantifies resistance to mechanical impacts. On a façade accessible to the public or exposed to vandalism, a high IK rating secures the installation and limits maintenance.

Beyond the ratings, thermal management and corrosion resistance determine the real lifetime (L70/L80) of the luminaires. Robust devices such as the REXPACK-300 are designed for these constraints. Find our solutions in the outdoor architectural lighting range.

Complying with the order of 27 December 2018 on light pollution

All outdoor lighting in France is governed by the order of 27 December 2018 on the prevention, reduction and limitation of light pollution. This text applies in particular to the lighting of heritage sites and buildings. Its main requirements:

Limitation of light emitted towards the sky: the share of flux emitted above the horizontal is strictly limited (a very small proportion), in order to reduce light pollution and the lighting of the night sky.
Switch-off periods: the lighting of façades and buildings must be switched off within defined time slots (as a general rule no later than one hour after the end of occupation of the premises, except in special cases), in order to limit the duration of night-time lighting.
Regulated colour temperature: for many outdoor uses, the shade is limited towards warm white (the text caps certain lighting at 3000 K, for example), which steers aesthetic choices.
Limitation of intrusive light: lighting must not cause excessive nuisance in neighbouring homes.

Exemptions exist for certain heritage sites and events. It is essential to check the framework applicable to your municipality and your project before any installation: a study takes these constraints into account from the design stage.

Controlling nuisance is not just an obligation: well-directed lighting, without spill or overconsumption, is also more economical and more respectful of residents and biodiversity.

Project method

Successful façade lighting follows an approach: analysis of the building (material, reliefs, surroundings), choice of techniques, selection of luminaires with the right IP/IK ratings and the right colour temperature, integration of regulatory constraints, then validation by a photometric study. The latter checks illuminance, uniformity and the absence of glare before any purchase, and guarantees the compliance of the result.

FAQ

What IP rating for a façade luminaire?

IP65 as a minimum for a façade exposed to bad weather. On sites very exposed to heavy water spray, favour IP66. If the installation is accessible to the public, add a high IK rating for impact resistance.

Can a façade be lit in cool white?

French regulations on light pollution restrict cool shades outdoors and cap many uses towards warm white (up to 3000 K depending on the case). Warm or neutral white should therefore be favoured, after checking the applicable framework.

Am I obliged to switch off façade lighting at night?

Yes, in most cases. The order of 27 December 2018 imposes switch-off periods for building lighting, with regulated exceptions. Control with time programming makes compliance easier.

Does grazing suit all façades?

No. Grazing enhances reliefs and textures, but it also accentuates the defects of an uneven surface. For a flat façade that is to look uniform, wall washing is preferable.

Need a photometric study? Designing your façade lighting is the work of a lighting design office: we recommend the expertise of the Luminance Consulting agency, the lighting design office that contributes to developing our ranges of luminaires based on an in-depth analysis of the needs of the most demanding customers. Rexylum supplies you with luminaires with suitable IP/IK ratings: contact us.