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Indicator Specification
A ‘Heating Degree Day’ (HDD) is a proxy for the energy demand needed to heat a home or a business; it is derived from measurements of outside air temperature. The heating requirements for a given structure at a specific location are considered to be to some degree proportional to the number of HDD at that location. However, they also depend on a large number of other factors, notably in relation to income levels, building design, energy systems and behavioural aspects. HDD are defined relative to a base temperature, the outside temperature below which a building is assumed to need heating.
Space heating is responsible for a large component of European energy use, so a decrease in the use of space heating has the potential to lead to a significant decrease in overall energy use. There are many contributory factors to heating demand, such as the energy performance of the building envelope, the type of heating system available, occupant behaviour and energy prices. However, the external temperature is the only component which is directly affected by climate change. The number of HDD is therefore a proxy for the energy demand for space heating, and hence an indicator for possible changes in overall energy use directly related to climate change.
An increase in cooling demand would off-set in part or completely the gains from a reduced energy demand for space heating and the effects resulting from a reduction in heating demand. While heating is delivered to end users in different ways (individual boilers fuelled by oil, gas, and coal, and electricity and district heating), cooling is delivered currently almost exclusively through electricity. As a result, a given increase in cooling demand is generally associated with higher costs, a higher increase in primary energy demand and larger impacts on the peak capacity of supply networks than the same decrease in heating demand.
In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.
The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.
No targets have been specified.
Eurostat calculates HDD as (18 °C - Tm) x d if Tm is lower than or equal to 15 °C (heating threshold) and zero if Tm is greater than 15 °C, where Tm is the mean (Tmin + Tmax / 2) outdoor temperature over a given period of d days.
A trend line has been added.
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Data for calculation of HDD have been collected by Eurostat for decades; this indicator can therefore be considered as very reliable. The same data used could also be used for the calculation of cooling degree days. Such an indicator is currently not available even though it would be highly policy-relevant and could be calculated with little additional effort. It should be noted that the indicator HDD is a purely physical metric, which does not consider differences in technical, social and economic factors (housing quality, behaviour, prices, etc.) between regions and their development over time.
Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/)
No uncertainty has been specified
Work specified here requires to be completed within 1 year from now.
Work specified here will require more than 1 year (from now) to be completed.
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/heating-degree-days-1 or scan the QR code.
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