- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 19 Jun 2017
According to BRE’s The essential guide to retail lighting:
Illuminance is ‘The level of light on a surface; measured in lux (lx). Previously called the illumination value. It can be used as a reference measurement of the performance of a lighting system as related to the activity.'
It is measured in lux (lx), the ‘...SI unit (the International System of Units) of illuminance or amount of light on a surface. One lux is equal to one lumen per square metre (lm/m^2)’ where a lumen (lm) is the ‘...SI unit of luminous flux, describing the quantity of light emitted by a lamp or received at a surface.’
Average illuminance is ‘The illuminance averaged over a specific area. In practice, this may be derived either from an average of the illuminances at a representative number fo points on the surface, or from the total luminous flux falling on the surface divided by the total area of the surface’
Maintained illuminance is ‘Illuminance at the time when maintenance is expected to take place. Most values of illuminance that are quoted as applicable to a store, eg 500-1000 lx, refer to this value. The time taken to reach the maintained illuminance level would depend on the lamp types and application’.
 Find out more
 Related articles on Designing Buildings Wiki
- Ballast or control gear.
- Colour appearance.
- Commercial lighting.
- Daylight benefits in healthcare buildings.
- Daylight factor.
- Daylight lighting systems.
- Dichroic reflector.
- Discharge lamp.
- Extra-low voltage lamps.
- General lighting v task lighting.
- Lamp efficacy.
- Light pollution.
- Lighting designer.
- Lighting energy numeric indicator LENI.
- Lighting of construction sites.
- Luminaire efficacy.
- Rights to light.
Featured articles and news
New ICE publication recommends pay-as-you-go tax to fund roads and other financing options.
BSRIA launches a White Paper on wearable technology and wellbeing in buildings.
Have the pressures of the market shredded the core values of professionalism?
Lead times are a measure of the amount of time that elapses between initiating and completing a construction process.
Government releases first tranche of funding for removal of unsafe high-rise cladding.
How to ensure UK transport infrastructure copes with severe winter weather.
Location shortlist for controversial new footbridge revealed.
Under the Party Wall Act a property owner has the legal right to do works that might otherwise constitute trespass or nuisance.
BSRIA examine the 'unpredictable' 2018 global air conditioning market.
The rainbow JCB will be making a welcome return to the London Build Expo on 23 and 24 October at Olympia.