Facade and Outdoor Lighting: How to Light a Building After Dark
Facade and Outdoor Lighting: How to Light a Building After Dark
A building has two designs. One is what the architect drew for daylight. The other only exists after dark, and almost nobody draws it with the same care.
That is a genuine opportunity, because facade lighting is one of the few remaining places in architecture where doing it properly is still rare. Most buildings at night are either unlit, lit by whatever happened to spill out of the windows, or lit by a few floodlights aimed up the wall with no more thought than that. A building lit with intent, where the material reads correctly, where the light has a hierarchy, and where it stops precisely at the edge of the site, still stands out.
This guide covers how to do that. It also covers something most facade lighting content leaves out entirely, which is that the rules governing outdoor lighting are almost never about how bright your building should be. They are about how much of your light is allowed to leave it.
Two Techniques That Do Opposite Things
Nearly every facade decision comes down to one question: do you want to reveal the texture of this surface, or flatten it into a smooth plane?
The answer determines everything else, and the mechanism is simply distance.
Grazing puts the fixture right up against the wall, aimed along it. Because the source sits so close, light strikes at a shallow raking angle, and every joint, bump and grain throws a small shadow. This is why grazing works so beautifully on stone, brick, board-marked concrete and timber. It makes texture visible at night in a way that flat midday daylight often does not.
It is also completely unforgiving. Grazing a badly finished wall does not hide the flaws. It catalogues them.
Washing does the opposite. The fixture sits further back with a wider beam, and the light arrives closer to straight-on, filling in shadows rather than casting them. The surface reads smooth, even and uniform. This suits render, painted surfaces, glass, and any building meant to be read as a clean volume rather than a textured one.
The manufacturer BEGA puts the threshold plainly in its technical guidance: a narrow beam distribution is the right choice for grazing when the fixture is mounted roughly 46cm (18 inches) or less from the surface, and that same narrow distribution is the best option for very tall facades. Wider or asymmetric distributions belong further back, for washing.
There is a third move worth knowing, and it is the one that produces the most memorable images. Silhouette lighting ignores the object entirely and lights what is behind it, so a balustrade, screen, tree or sculptural element reads as a dark shape against a glowing backdrop. It is the only one of the three techniques where the thing you care about receives no light at all.
How Far Back, and How Wide
Once you know which technique the material wants, two numbers follow.
Grazing wants a narrow beam, broadly in the 10 to 30 degree range, mounted close, within roughly that 46cm threshold.
Washing wants a wide or asymmetric beam, generally above 60 degrees, mounted further out. The rule of thumb in common use is to offset a ground-mounted wall washer from the building by one third to one half of the facade height, which stops shadows from balconies and cornices stretching absurdly up the wall.
| Facade height | Offset at one third to one half |
|---|---|
| 6m, a two-storey house | 2 to 3m |
| 12m | 4 to 6m |
| 20m | 6.7 to 10m |
Two honest caveats. This offset rule is widely repeated design practice rather than a published standard, so treat it as a starting point. And it collides with reality constantly, because the space it asks for is usually a pavement, a road or somebody else's property. Half the craft of facade lighting is negotiating that gap.
On tall buildings, the whole approach changes. Lighting twelve storeys from a single row of ground-level fixtures produces a bright, over-lit base and a weak, patchy top, which is the most common failure in the whole discipline. The fix is to break the height into stages, mounting additional fixtures on balconies, ledges or setbacks so each section of the building is lit from a sensible distance rather than thrown at from far below.
Colour Temperature, and Why It Matters More Outside
The colour temperature rule that governs interiors applies outdoors too, but the stakes are higher, because the comparison a viewer makes is not to the room next door. It is to the night sky and the street.
2,700 to 3,000K is the standard choice for buildings in warm, organic materials: brick, timber, natural stone, terracotta. Warm light on warm material reads as a single coherent thing.
Cooler temperatures can suit contemporary palettes of glass, metal and polished concrete, but they carry a risk that is easy to underestimate. Cool white light against a warm-lit street and a warm night sky rarely reads as modern. It reads as institutional, and it is the difference between a building that looks designed and one that looks municipal.
Consistency matters here exactly as it does indoors. A warm-lit facade with a cool white entrance canopy or signage band produces a visible seam that undoes the whole scheme, and it is one of the most common defects on otherwise well-considered buildings.
Lighting Glass Without Turning It Into a Mirror
Glass is the material most often lit badly, because the intuitive approach is close to the worst available.
Point a floodlight at glass and you do not illuminate it. You get hotspots, mirror-like reflections and glare, because glazing reflects far more than it reveals. The building ends up looking like it has been caught in headlights.
The approach lighting designers actually use on contemporary glass buildings is indirect. Light the structure around the glass rather than the glass itself: wash or graze the mullions, fins, structural framing and spandrel panels, which articulates the facade's rhythm and geometry without a single reflective hotspot. Backlighting behind frosted or fritted panels, or linear light concealed at floor and ceiling junctions behind curtain walling, turns a glazed volume into a softly glowing form rather than a dark reflective slab.
Watch colour temperature carefully on tinted or coated glazing, since the glass itself shifts the colour of anything seen through or reflected in it. A source that reads perfectly on adjacent stone can read distinctly wrong once filtered through green-tinted glass a few metres away.
The Thing Nobody Tells You About Outdoor Lighting Rules
Here is the point that reframes this entire subject.
There is no standard telling you how bright your facade should be. Interior lighting has prescriptive tables everywhere: an office needs this many lux, a retail sales floor needs that many. Decorative facade lighting has no equivalent. How much light a building carries at night is, almost entirely, a design decision.
What is regulated, and increasingly tightly, is how much of that light escapes. This is called obtrusive light, and once you know the framework, a great deal of otherwise confusing planning feedback starts making sense.
The leading international reference is CIE 150:2017, Guide on the Limitation of the Effects of Obtrusive Light from Outdoor Lighting Installations, published by the International Commission on Illumination. It works by first asking a question about your site rather than your building: how dark is it here already?
That produces five environmental zones:
| Zone | Description | Example |
|---|---|---|
| E0 | Intrinsically dark | Dark sky parks, major observatories |
| E1 | Dark | Relatively uninhabited rural areas |
| E2 | Low district brightness | Sparsely inhabited rural areas |
| E3 | Medium district brightness | Well inhabited urban and rural settlements |
| E4 | High district brightness | Town and city centres, commercial areas |
Each zone then caps the upward light ratio (ULR), the share of a fixture's total output that escapes above the horizontal and lights nothing but the sky. Guidance published by the Institution of Lighting Professionals, quoting CIE 150's own table, gives these maximums:
| Zone | Maximum ULR |
|---|---|
| E0 | 0% |
| E1 | 0% |
| E2 | 2.5% |
| E3 | 5% |
| E4 | 15% |
Notice what those first two rows mean in practice. In genuinely dark environments, the permitted upward light is zero. Not minimal. Zero. A fixture that meets this is called full cutoff, emitting nothing above the horizontal plane at all, and it forms part of the IES BUG rating system (Backlight, Uplight, Glare) used to classify outdoor luminaires.
In the United States, the parallel framework is the Model Lighting Ordinance, developed jointly by DarkSky International, formerly the International Dark-Sky Association, and the Illuminating Engineering Society, first approved in 2011. It uses an equivalent five-zone system, LZ0 to LZ4, which individual municipalities adopt into local code. Thousands of US jurisdictions now have some form of outdoor lighting ordinance built on it.
In Europe, note that EN 12464-2 covers outdoor work places, things like loading bays and yards. It is a different document from the obtrusive light framework and does not set decorative facade levels. The two get confused often.
Local rules add real numbers on top of all this. To give one example rather than a universal figure: San Bernardino County in California caps light trespass at 0.5 footcandle at a residential property line, tightening to 0.1 footcandle in its mountain and desert regions. The figure that applies to your project is set locally and has to come from the planning authority, not from a guide like this one.
One last practical note that increasingly decides schemes: many jurisdictions now impose a curfew, a time after which decorative facade lighting must dim or switch off entirely. Specifying that control at design stage costs almost nothing. Retrofitting it after a planning condition lands is a different conversation.
The Bird Problem Almost Nobody Mentions
This section deserves its place because the numbers are far larger than most designers expect, and because the fix is genuinely cheap.
Peer-reviewed research estimates that between 365 and 988 million birds die each year in the United States from collisions with buildings and glass. That figure comes from work by Loss and colleagues and is cited directly by the US Fish and Wildlife Service. Artificial light at night is a major contributing factor, because nocturnally migrating birds are drawn toward and disoriented by lit structures.
Now the part that overturns the usual assumption. Most people picture a mirrored skyscraper when they hear about bird strikes. The research says otherwise: roughly 56 percent of collision mortality occurs at low-rise buildings of four to eleven storeys, around 44 percent at urban and rural residences, and well under 1 percent at high-rises.
It is not the towers. It is ordinary buildings, at ordinary heights, of the kind most architects actually design.
The scale of the lighting effect has been measured. A 2021 study in Chicago found that halving the number of lit windows in large buildings reduced bird collisions by somewhere between six and eleven times. Cities including New York, Chicago and Philadelphia have since introduced or debated lights-out programmes during migration season.
What to actually do about it, none of which compromises a good scheme:
Put decorative lighting on a curfew. The NYC Bird Alliance recommends switching off exterior floodlights, spotlights and decorative lighting from 11pm to 6am during peak migration, which it defines locally as April 1 to May 31 and August 15 to November 15. Those dates are specific to New York's position on the Atlantic Flyway, so check what applies in your region, but the principle travels.
Shield and aim precisely. This is the same discipline that obtrusive light control already demands. Light that lands only on the facade, with nothing spilling upward, is both compliant and less disorienting.
Favour warmer colour temperatures, which are understood to be less disruptive to migrating birds than cool, blue-rich light. Conveniently, that is the same conclusion the material and atmosphere argument reached earlier.
Take extra care near vegetation and water, which concentrate bird activity, particularly where lit glazing sits nearby.
The overlap here is the useful part. A scheme with tight upward light control, sensible curfews and warm colour temperature is already most of the way to being bird-considerate. The same discipline serves both ends.
Facade Lighting Design Checklist
Before designing
- Facade material identified: does it want grazing, washing, or both on different elements?
- Facade height measured, to inform mounting offset for washing
- Environmental zone (E0 to E4, or local equivalent) established for the site
- Local outdoor lighting ordinance checked with the planning authority
- Curfew or dimming requirement confirmed, if any applies locally
- Proximity to water, significant vegetation or a known migration corridor noted
Technique and fixtures
- Grazing fixtures at a narrow beam, roughly 10 to 30 degrees, mounted close to the surface
- Washing fixtures at a wide or asymmetric beam above 60 degrees, offset per facade height
- Tall facades broken into stages with intermediate mounting, not lit from ground alone
- Glass lit indirectly via mullions, fins or framing, never floodlit directly
- Colour temperature consistent across facade, signage and entrance
- Fixtures selected with a stated ULR and BUG rating suited to the site's zone
Compliance and neighbours
- Upward light ratio checked against the applicable zone limit
- Light trespass at the property boundary checked against local limits
- Fixtures full cutoff or shielded where the zone requires it
- Timer, curfew or dimming control specified at design stage
- Scheme reviewed against migration guidance where region and site warrant it
Six Mistakes in Facade Lighting
1. Washing a surface that wanted grazing. A textured stone or brick facade lit with a wide, distant wash goes flat and loses the exact quality that made the material worth using.
2. Floodlighting glass head-on. Hotspots and mirror glare instead of illumination. Light the frame or what sits behind it.
3. Lighting a tall building from one row of fixtures at the base. Bright bottom, weak top. Break the height into stages.
4. Ignoring upward light. A scheme with no stated ULR is a scheme that has not asked where its light actually goes, and increasingly one that fails a planning condition.
5. Leaving it all on until dawn. The biggest single lever on bird collision risk, and the fix is a timer rather than a redesign.
6. A cool white sign on a warm building. A visible seam that quietly undoes an otherwise careful scheme.
Frequently Asked Questions
What is the difference between wall washing and wall grazing? Grazing places the fixture very close to the wall, roughly within 46cm (18 inches), using a narrow beam of about 10 to 30 degrees, so light strikes at a shallow angle and reveals texture through small shadows. It suits stone, brick, timber and board-marked concrete. Washing places the fixture further back with a wide or asymmetric beam above 60 degrees, producing smooth even illumination with little shadow, which suits render, painted surfaces and glass. The two are not interchangeable: washing a textured facade flattens the very quality worth showing, and grazing a smooth one can look patchy.
How far should a wall washer be from the building? A widely used starting point is to offset the fixture by roughly one third to one half of the facade height, which keeps shadows from balconies and cornices from stretching too far up the wall. On a 12m facade that is around 4 to 6m. This is design practice rather than a published standard, and site constraints such as a narrow pavement or a close boundary frequently override it. On tall buildings a single ground-level throw rarely lights the full height evenly, so fixtures at intermediate levels are usually necessary.
What colour temperature should facade lighting be? 2,700 to 3,000K for buildings in warm, organic materials such as brick, timber, stone or terracotta, since warm light and warm material read as one coherent thing. Cooler temperatures can suit contemporary glass and metal, but carry a real risk of reading institutional rather than modern against a warm-lit street. Keep colour temperature consistent across the entire scheme, including signage and entrance lighting, because any mismatch produces a visible seam.
How do you light a glass building without it looking like a mirror? Do not light the glass directly. Glazing reflects far more than it reveals, so a floodlight aimed at it produces hotspots and glare rather than illumination. Light the structure around it instead: wash or graze the mullions, fins, structural framing and spandrel panels, or backlight frosted and fritted sections. This articulates the building's rhythm and geometry without a single reflective hotspot. Take particular care with colour temperature on tinted or coated glazing, which shifts the colour of anything seen through it.
What is obtrusive light and how is it regulated? Obtrusive light is light escaping beyond where it is needed, contributing to sky glow, glare or trespass onto neighbouring property. The leading international framework is CIE 150:2017, published by the International Commission on Illumination, which defines five environmental zones from E0 (intrinsically dark, such as observatories) to E4 (city centres), each with a maximum upward light ratio: 0% for E0 and E1, 2.5% for E2, 5% for E3, and 15% for E4. In the United States the equivalent is the Model Lighting Ordinance, developed by DarkSky International and the Illuminating Engineering Society and adopted locally using a parallel LZ0 to LZ4 system. Local ordinances usually add specific numeric limits, which must be confirmed with the relevant planning authority.
Is there a standard for how bright a facade should be? Not in the way there is for interiors. Indoor standards set specific illuminance tables for offices, shops and other named spaces, but decorative facade lighting largely falls outside that kind of prescriptive coverage, and how much light a building carries is primarily a design decision. What is regulated, increasingly tightly, is how much light escapes the site as sky glow, glare or trespass, governed by frameworks such as CIE 150 and by local ordinances rather than by any facade brightness table. Note that EN 12464-2 covers outdoor work places such as loading bays and yards, not decorative facade lighting, and the two are often confused.
Does facade lighting really affect birds? Yes, and at a scale most designers underestimate. Peer-reviewed research cited by the US Fish and Wildlife Service estimates between 365 and 988 million birds die annually in the United States from building and glass collisions, with artificial light at night a significant contributing factor because it attracts and disorients nocturnal migrants. Counterintuitively, it is not mainly skyscrapers: roughly 56 percent of mortality occurs at low-rise buildings of four to eleven storeys and around 44 percent at residences, with well under 1 percent at high-rises. A 2021 Chicago study found halving the number of lit windows in large buildings cut collisions by roughly six to eleven times.
When should facade lighting switch off for bird migration? The NYC Bird Alliance recommends turning off exterior floodlights, spotlights and decorative lighting from 11pm to 6am during peak migration, which it defines as April 1 to May 31 and August 15 to November 15. Those dates reflect New York's position on the Atlantic Flyway, so the specific window varies by region and by which species migrate locally, but the principle applies broadly. Specifying a timer or curfew control at design stage, rather than relying on somebody remembering to switch things off, is the only reliable way to achieve it.
Notice
This article is published by Archlior for general information and educational purposes. It is written for architects, interior designers and specifiers as an introduction to facade and outdoor lighting design.
It is not professional lighting design advice, engineering advice, ecological advice, or a statement of regulatory compliance for any project.
Outdoor lighting regulation, including obtrusive light limits, environmental zone classification, light trespass thresholds and curfew requirements, is set locally and varies significantly by country, region and municipality. Figures in this guide, including the CIE 150 environmental zone and upward light ratio values, are drawn from published standards summaries and professional guidance as indicated in the text. Any specific local limits mentioned are illustrative examples rather than universal requirements. All figures must be verified against the applicable local planning and lighting authority before a project proceeds.
Guidance on bird-safe lighting reflects published research and conservation organisation recommendations at the time of writing, and migration timing varies by region and species. It is not a substitute for advice from a qualified ecologist where a project warrants it.
Archlior accepts no liability for any loss, cost or damage arising from reliance on the information in this article. Readers act on it at their own discretion and remain responsible for compliance with all applicable regulations.
Last reviewed: August 2026.