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 and news
Registered building inspectors
Building types and conflicts of interest updates explaineed.
Engineering services still struggle with labour shortages
According to latest quarterly services survey of the sector.
Infrastructure that connect the physical and digital domains.
Harnessing robotics and AI in challenging environments
The key to nuclear decommissioning and fusion engineering.
BSRIA announces Lisa Ashworth as new CEO
Tasked with furthering BSRIA’s impressive growth ambitions.
Public buildings get half a million energy efficiency boost
£557 million to switch to cleaner heating and save on energy.
CIOB launches pre-election manifesto
Outlining potential future policies for the next government.
Grenfell Tower Inquiry announcement
Phase 2 hearings come to a close and the final report due in September.
Progress from Parts L, F and O: A whitepaper, one year on.
A replicated study to understand the opinion of practitioners.
ECA announces new president 2024
Electrical engineer and business leader Stuart Smith.
A distinct type of countryside that should be celebrated.
Should Part O be extended to existing buildings?
EAC brands heatwave adaptation a missed opportunity.
Definition of Statutory in workplace and facilities management
Established by IWFM, BESA, CIBSE and BSRIA.
Tackling the transition from traditional heating systems
59% lack the necessary information and confidence to switch.
The general election and the construction industry
As PM, Rishi Sunak announces July 4 date for an election.
Eco apprenticeships continue help grow green workforce
A year after being recognised at the King's coronation.