A fair comparison of CO2 emissions requires a more detailed analysis

The diverse uses of public buildings make measuring efficiency a complex task

Philip Steadman
The Guardian, Tuesday 12 January 2010
Your article reported some useful data on carbon emissions (Red faces as hospitals and prisons rank bottom in public buildings CO2 audit, 1 January). These come from the energy certificates that all public (but not yet private) buildings must display.
There are huge opportunities for improvements here, some of them simple changes in behaviour, others needing investment in fabric, heating systems, air conditioning and lighting. But your analysis by average emissions per building is misleading.
You label New Scotland Yard "the most polluting police station" and praise the station at Whetstone as "one of the most efficient". But Scotland Yard is a much bigger building. Broadly speaking, energy use in buildings increases with floor area, so one needs to calculate figures per square metre as a more meaningful basis for comparing efficiencies.
Although floor area and other factors are taken into account in the energy certificate scores A to G which you report, these distinctions are lost by taking averages. You pick out prisons and hospitals as "the biggest polluters on average", while "schools are relatively energy-­efficient". But the average hospital in England and Wales has more than five times the floor area of the average school.
Then there are the different uses to which buildings are put. Hospitals and prisons are not only large institutions, they run 24 hours a day, 365 days a year, and use a lot of energy for cooking, laundry and hot water – unlike, say, law courts or citizens' advice bureaux. Given their special functions, it is possible that some individual prisons and hospitals are relatively efficient in their own terms.
A more comprehensive approach is needed. Since 1990 I have been working with colleagues on energy use in the entire non-domestic building stock of England and Wales. The task is complex because of the diversity of activities, the range of sizes of buildings, and the fact that many commercial buildings contain mixtures of shops, offices, clubs, restaurants, etc. Many private sector buildings – which are much more numerous – are possibly even less efficient than those in the public sector.
One hears much rhetoric about Britain's post-industrial economy but, by our estimates, industrial buildings in England and Wales use around 60,000 gigawatt-hours annually (for the ­buildings only and excluding industrial processes). This compares with some 55,000 gigawatt-hours for schools, ­hospitals and offices put together.
In an excellent initiative, the Department of Energy and Climate Change is developing two new databases that will link information on floor area and activities for all buildings in the country – domestic and non-domestic – to their energy bills. The domestic database is well advanced, the non-domestic at the pilot stage. Our team at the UCL Energy Institute is helping and advising. These databases will make it possible to compute national average levels of energy use per square metre, against which the efficiency of any individual building can be compared. And it will be possible to estimate the likely impact of future programmes and to monitor them as they are implemented.