Degree day analysis helps organisations to evaluate energy performance

Deciphering the impact of efficiency measures on your energy consumption from the noise of seasonal influence can be challenging.  All it takes is one harsh winter and all reduction targets are off. One method for improving your understanding of anticipated and actual energy consumption is to undertake an exercise known as degree day analysis.

For those new to the topic, degree days are a measure of the severity and duration of adverse weather, both hot and cold. Every degree Celsius above or below a set base temperature counts as a degree day. The cumulative degrees days for a specific day, month or year gives an indication of what the weather was like during that period. More importantly, they can tell us how hard our heating systems are working to compete with fluctuation in outside temperature.

Fortunately the winter of 2013/14 has been mild, resulting in reduced gas and electricity heating bills across the board. A question to ask is, have you reacted and adjusted your current energy management to benefit from potential cost, resource and emission savings? Using degree days to monitor the influence of weather on energy consumption profiles will identify opportunities for savings and isolate anomalies from expected consumption (i.e. increased consumption due to renovation works, a faulty meter, a busy visitor period, etc.).

Carbon Smart recently completed degree day analyses with the Home Office and the Religious Society of Friends to understand how the harsh winter of 2012/13 impeded their energy saving efforts. For the Home Office, the results concluded that despite the harsher weather, they achieved a 41% reduction in carbon emissions compared to forecasted levels. Our evaluation also highlighted that under favourable weather conditions a further 30% reduction could have been achieved. The analysis provided confirmation that the energy savings measures had been a success and strengthens the argument to continue their efforts going forward.

How can degree day analysis help you?

  • Degree days can inform adjustments for thermostat set point and Building Management Systems to reduce overall building        energy consumption
  • Identify expected and forecasted savings from actual consumption
  • Understand performance improvements against year on year targets as a result of energy efficiency measures and forecast          ongoing trends
  • Isolate anomalous data and highlight potential energy savings opportunities

For further details on how degree day analysis can support and interpret your energy saving efforts, contact Becky at or call 0207 920 8285.

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