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
efficiency)
- Evaluating success of savings measures
- Detecting faults in heating systems and their control
- Preparing annual budgets
The Degree days for energy
management (CTG004) publication provides an introduction
to degree days and shows how simple analysis can be a powerful tool
in understanding weather-related energy consumption.
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
supplementary heating.
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
temperature of:
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
available from:
University of Oxford
Environmental Change Institute (ECI): Degree day downloads
(opens in new window).
Download Degree
days for energy management (CTG004)