Illuminance data were collected from 18 UK dwellings during 1-week periods in spring 2007, to establish when luminaires were used and to calculate electricity consumption for lighting. Householders were also interviewed about lighting use and choices. The potential for reducing lighting electricity consumption by replacing incandescent bulbs with compact fluorescent lamps (CFLs) is assessed. Mean weekly electricity consumption for lighting was 3.756 kW h and mean proportion of total electricity consumption used for lighting was 6.55%. It is notable, however, that participants generally expressed high levels of environmental awareness and that electricity consumption figures for less environmentally-aware households may differ. On average, households could have reduced lighting electricity consumption by 50.9% if all incandescent bulbs were replaced with CFLs. Even householders making extensive use of efficient lighting technologies expressed concerns about these technologies' performance, but seemed willing to tolerate perceived shortcomings for environmental reasons. However, the study raises questions about whether people without strong environmental motivations can be convinced that efficient lighting technologies will meet their needs. It also raises questions about the effectiveness of policies phasing out general lighting service incandescent bulbs, as there is a risk that householders may switch to tungsten halogen bulbs rather than low-energy options.