Using degree days for energy management
Four valuable uses of degree days in energy management are:
- Constructing control charts that compare benchmarked and actual
energy usage (the closer they are, the greater your energy
- Evaluating success of savings measures
- Detecting faults in heating systems and their control
- Preparing annual budgets
The Degree days for energy
management (CTG075) publication (updated from CTG004)
provides an introduction to degree days and shows how simple
analysis can be a powerful tool in understanding weather-related
Degree days: technical details
The base temperature used to calculate degree days in the UK is
15.5ºC, because at this temperature most UK buildings do not need
Degree days is a measure of the difference between the baseline
and the actual outdoor temperature multiplied by the number of
days. For example - the temperature measured hourly records a
7.5ºC for 48 hours the degree days total would be: (15.5 - 7.5)
x 2 = 16
Note - it is not possible to have a negative degree day value as
when the outdoor temperature exceeds 15.5ºC no heating is needed.
When the outdoor temperature does exceed the 15. 5ºC baseline, then
the degree days are set to zero.
Download degree day data
The Carbon Trust no longer supplies this data, but it is freely
University of Oxford
Environmental Change Institute (ECI): Degree day
downloads(opens in new window).
days for energy management (CTG075)
Support for energy efficiency
If you're looking to cut energy costs and improve energy
efficiency of your organisation, see our services to find out how we can
help. This includes financing and implementation support for
organisations seeking to invest in energy efficient equipment.
Visit our regional web pages for Scotland, Wales and Northern Ireland to get details
of our government-funded support.