The environmental cost of leaving the lights on

If all UK offices switched their lights off at night the carbon savings could be phenomenal according to recent research. Time to acts writes Henrietta Lynch

Recent research carried out as part of the CaRB (Carbon Reductions in Buildings) programme, at the Bartlett School of the Environment, UCL (University College London) has shown that there may be the potential to save around 1.4–1.6 TWh of electricity each year in the UK, just by turning office lights off when they are not needed after working hours. This corresponds to about 1 million tonnes of CO2 and would be enough to light about 1.5 million homes a year.

The research which was undertaken in conjunction with Worcester Polytechnic Institute, Massachusetts, USA, looked at a sample or around 140 office buildings in the West End of London between the hours of 10pm and 3am in January and February this year. The study involved an analysis of lights being left on during this period with this information being used to generate useful profiles to estimate 24 hour use of lighting in UK office buildings.

Typically offices are only occupied for between 25-30% of the hours in a week so a small percentage of lights left on overnight and through the weekend wastes a huge amount of energy. This study shows that of the total lighting use in offices between 24-30% is being wasted.

There is confidence that the results of this research provide a typical picture of ‘after hours’ office lighting in the UK and could potentially be applied to other similar industrialised nations such as the USA, Australia, New Zealand and Japan where anecdotal evidence points to similar situations.

Typically offices are only occupied for between 25-30% of the hours in a week so a small percentage of lights left on overnight and through the weekend wastes a huge amount of energy

Imagine therefore the huge potential for energy and CO2 savings that could be achieved by turning unnecessary night-time office lighting off! What is more, these savings could be relatively easily achieved through simple and cost effective systems lighting control systems, as well as through a general awareness of the problem.

In today’s environmental and economic climate surely turning unwanted lights off when they are not needed is a no-brainer!

The CaRB project is a £3million project funded by the EPSRC (Engineering and Physical Sciences Research Council) and the Carbon Trust under the Carbon Vision Buildings (CVB) programme. The Bartlett at UCL is part of a consortium of five UK Universities involved with three projects with a total of £5million of CVB funding.