How Heating Degree Days can Inform Energy Management

Manchester is my Planet has utilised data from www.degreedays.net to help inform the forthcoming Sustainable Energy Action Plan for Greater Manchester.

Heating Degree Days are a valuable measure for understanding energy use in buildings, as it allows you to factor in the changes in outside temperature with energy consumption for heating. 

How are heating degree days calculated?

When each day’s average air temperature falls below a base temperature (usually 15.5 ^oc for the UK):

Multiply the difference between the day’s average temperature (a) and the base temperature (b), by the number of days (c). For example;

Average air temperature on a given day = 10.5 ^oc (a) – 15.5 ^oc (b) x 1 day = 5 Degree Days.

Heating Degree Days assist the energy manager in identifying inefficient heating systems or poor energy management behaviours. Put simply, if the number of heating degree days for your area is low, and your heating demand is high, you are likely to have a heating management issue.

Manchester is my Planet used Heating Degree Days as a Key Performance (KPI) in the Sustainable Energy Action Plan. The Degree Day data from across Greater Manchester when correlated against domestic gas use enables us to see if our efforts to save energy have been effective.

Greater Manchester Domestic Gas Use & Degree Days

This graph shows that over the last four years domestic gas use has steadily reduced, in line with a reduction in Heating Degree Days. However between 2007 and 2008 the number of degree days rose significantly without corresponding rise in gas demand. This suggests improved insulation and energy management.

It would be better to have a longer time period to observe this correlation and obviously there are a number of other factors which need to be accounted for such as economic down turn, number of weather stations etc before drawing full blown conclusions from such data. However, taking these issues take into account, the graph suggests early signs that energy efficiency measures are making a positive difference.

We have made recommendations to the Association of Greater Manchester Authorities to use Degree Days as a KPI to measure energy efficiency, forecast energy demand for heating, cooling and monitoring the effects of climate change in Greater Manchester.

The Sustainable Energy Action Plan is due for publication at the beginning of summer 2010.

How might Greater Manchester generate, supply and use energy in 2050?

A new report from Manchester: Knowledge Capital and Carbon Captured highlights different pathways that Greater Manchester might take in responding to the challenge of meeting an 80-90% cut in CO2 emissions by 2050.

The Manchester is my Planet programme brought together local stakeholders from public, private, academic and non-government sectors to co-create three future energy scenarios for Greater Manchester.

In all of the scenarios, energy use by consumers is expected to fall considerably – despite incorporating expectations for population growth and increases in the number of household appliances.

Differences in economic growth rates are also plotted in the scenarios. The report suggests that even factoring in strong growth, Greater Manchester can achieve its fair share of CO2 cuts.

The collective learning gained through the process, and the resulting report, has fed the development of the forthcoming Sustainable Energy Action Plan for Greater Manchester – a coherent strategy for accelerating the development of a low-carbon energy system for Manchester.

Dr Cathy Garner, Chief Executive of Manchester: Knowledge Capital welcomed the report: “The scenario development process not only contributes to the body of knowledge that Greater Manchester requires as it makes the transition to a low-carbon future, but the results clearly demonstrate the great value of working collaboratively across sectors.”

The ‘GRIP Scenario Tool’ used in this work was developed by Dr Sebastian Carney, of Carbon Captured, and has been recommended for use by regions and municipalities throughout the EU under the Covenant of Mayors initiative.

Download your own copy of the Developing Future Energy Scenarios report.

The development of this report has been funded by the EU’s Intelligent Energy in Europe Programme and the North West Development Agency.