In short
- People judge brightness by what they see: walls, faces and objects. Most of that is vertical. Floors and desks are horizontal.
- A room lit on its walls feels brighter, larger and calmer than a room with more lux on the floor and dark walls.
- Design for luminance in the field of view, then check task illuminance, not the other way round.
Lux on the floor, darkness on the walls
Many lighting layouts are driven by a grid of downlights and a horizontal lux target at floor or desk level. The calculation passes. The room still feels dim.
The reason is simple: we look at walls, not floors. The surfaces in the field of view, and how bright they appear, shape our sense of how lit a room is.
- Horizontal illuminance (lux on a floor or desk) matters for tasks.
- Vertical illuminance (lux on walls and faces) matters for perception, orientation and recognition.
- Luminance (how bright a surface appears, which depends on light and reflectance) is what the eye actually sees.
Narrow-beam downlights, covered in our beam angle guide, put light on the floor efficiently. They rarely light walls well unless placed and aimed for it.
What lit walls do
- Perceived brightness rises even when total lumens stay the same or drop.
- Spaces feel larger. Lit boundaries push walls outward visually; dark walls close in.
- Glare reduces. Bright downlights against a dark ceiling and walls create high contrast; lit walls lower it.
- Faces become readable. Vertical light on people improves recognition and conversation.
- Materials appear. Stone, timber and textiles are vertical surfaces in most rooms.
Ways to light a wall
| Technique | Effect | Detail |
|---|---|---|
| Wall washing | Even, flat light across the wall | Asymmetric washers or lensed slots, set back from the wall |
| Grazing | Strong texture, raking shadows | Source close to the wall, narrow or linear |
| Scalloping | Pools and rhythm | Downlights near the wall; intentional, not accidental |
| Indirect from a cove | Soft light on upper wall and ceiling | Cove at the wall head |
| Accent on objects | Focus on art and features | Narrow beams; see our beam angle guide |
Washing versus grazing
- Wash smooth plaster, art walls and paint finishes. Uniformity is the aim, and texture is hidden.
- Graze stone, brick, timber battens and textured plaster. Texture is the aim, and every bump in a flat wall will also show. Grazing on poor plaster reveals defects.
Distances
- Washers usually sit around a quarter to a third of the wall height away from the wall (convention), with spacing close to the setback.
- Grazers sit close to the wall, typically within 100–300 mm.
- Check the manufacturer’s photometry for the specific fitting.
Choosing which walls
Not every wall needs light. Choose:
- The wall you face on entering. It sets the first impression.
- The far wall of a deep room. It draws people in and makes depth legible.
- Walls with material value. Stone, timber, art.
- Walls behind people. A lit wall behind a sofa or a reception desk separates figures from background.
Leave other walls lower. Contrast between lit and unlit walls is part of the design.
Offices and workspaces
- Lit walls reduce the “cave effect” of open offices lit only by downlights or panels.
- Vertical light on faces matters for meetings and video calls.
- Combining wall washing with lower horizontal levels can feel brighter with less glare. See Beam Angle in Office Lighting.
Residences
- Living rooms benefit from washing one or two key walls and lowering ambient downlights.
- Bedrooms feel calmer with a soft wall wash behind the bed rather than overhead light.
- Double-height spaces need vertical light to stay legible; see Double-Height Spaces.
Reflectance matters
- A light wall returns much more light than a dark one. A dark feature wall will absorb a wash and look dull.
- Matt finishes give even washes; gloss mirrors sources.
- Choose finishes and lighting together.
Specification notes
- Set targets for vertical illuminance on key walls, not only horizontal lux.
- Identify the walls to light on plan: entry view, far wall, material walls, walls behind people.
- Use washers for smooth walls and grazers for texture; check plaster quality before grazing.
- Place washers by photometry; record setbacks and spacing on the drawings.
- Coordinate wall finishes and reflectance with the lighting design.
Frequently asked questions
What is vertical illuminance?
The amount of light falling on a vertical surface such as a wall or a face, measured in lux. It drives how bright a room feels, even though most standards focus on horizontal illuminance.
Why does my room feel dark with plenty of downlights?
Downlights put light on the floor. If the walls and ceiling stay dark, the surfaces you actually see are dim. Lighting one or two walls often fixes this.
Should I wash or graze a feature wall?
Wash smooth surfaces for even light; graze textured stone, brick or battens to reveal texture. Grazing exaggerates every imperfection, so check the wall finish first.
Continue the series
- Beam Angle in Lighting Design
- Beam Angle in Living Spaces
- Double-Height Spaces
- Light as a Line
- Glare Beyond UGR
About the author
Prem Rout, Founder of JMAP Solutions, set up in 2022 to deliver lighting, automation and building management solutions from Bhubaneswar. Over 15 years of experience in building products, construction and project business development across Mumbai and Odisha, working where design intent meets specification and site delivery. Connect on LinkedIn.
