Circuit-watt
According to the Domestic Building Services Compliance Guide published by HM Government in 2013, the term ‘circuit-watt’ refers to:
| The power consumed in lighting circuits by lamps, and where applicable, their associated control gear (including transformers and drivers) and power factor correction equipment. |
'Lamp lumens per circuit-watt is the total lamp lumens summed for all luminaires in the
relevant areas of the building, divided by the total circuit-watts for all the luminaires.'
'Luminaire lumens per circuit-watt is the (lamp lumens x LOR) summed for all luminaires
in the relevant areas of the building, divided by the total circuit-watts for all the luminaires.'
Ref Non-domestic Building Services Compliance Guide For Scotland, 2015 Edition v1.1, published by the Scottish Government, Building Standards Division in April 2018.
NB Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments, suggests that circuit-watt: ‘Refers to the power consumed in lighting circuits by lamps and, where applicable, their associated control gear (including transformers and drivers) and power factor correction equipment.’
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