Lamp efficacy
According to BRE’s The essential guide to retail lighting:
Lamp efficacy (or luminous efficacy) is ‘The ratio of the light output from a light source to the power consumed; measured in lumens per Watt (lm/W). The higher the efficacy value of a lamp or lighting system, the more energy-efficient it is.’
‘For example, the efficacy of a 60 W incandescent light bulb is 12 lm/W, and of an 11 W CFL (compact fluorescent lamp) is 55 lm/W. For a 36 W fluorescent tube it is 91 lm/W. This last figure is a lamp efficacy; it excludes the power consumed by the ballast that is needed to run the discharge lamps.’
Ballast or control gear, is ‘Part of the control equipment of fluorescent or discharge lamps, used to stabilise the current. The older, traditional main-frequency ballast can consume up to 20-25% of the total lamp current. A modern electronic ballast working at high frequency consumes about 30% less current, and can be used to regulate or dim the lamp output.’
See also: Lighting efficacy
[edit] Related articles on Designing Buildings Wiki
- Artificial lighting.
- Ballast or control gear.
- Colour appearance.
- Colour Rendering Index CRI.
- Daylight benefits in healthcare buildings.
- Daylight factor.
- Daylight lighting systems.
- Dichroic reflector.
- Discharge lamp.
- Extra-low voltage lamps.
- General lighting v task lighting.
- Illuminance.
- Lamps.
- Light pollution.
- Lighting.
- Lighting efficacy.
- Lighting energy numeric indicator LENI.
- Lighting of construction sites.
- Luminaire efficacy.
- Lux.
- Rights to light.
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Listed structures on the rail network
Heritage interests and operational requirements must be balanced.
Historic England publishes research into embodied carbon when retrofitting traditional buildings.
New Prime Minister delivers on ECA call for cut in electricity costs.
CIOB reacts to the announcement of Andy Burnham as Prime Minister.
Heritage and conservation science workforce survey - Have your say.
England's Suburbs 1820-2020. Book review.
New, more proportionate and targeted approach for higher-risk building assessments.
Government brings British Steel into public ownership.
UKCW Birmingham returns with bold new theme and focus.
New guidance published on competence requirements for self-certification schemes.
Construction Management, 8 July
NEETs crisis drives interest in trades, but apprenticeships barriers remain.
Passive fire protection webinar
MEP services penetration seals.