Indicator Assessment

Heating degree days

Indicator Assessment
Prod-ID: IND-348-en
  Also known as: CLIM 047
Published 20 Nov 2012 Last modified 11 May 2021
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  • The number of heating degree days (HDD) has decreased by an average of 16 per year since 1980. This helps reduce the demand for heating, particularly in northern and north-western Europe.
  • Climate change will affect future energy and electricity demand. Climate change is not expected to change total energy demand in Europe substantially across Europe, but there may be significant seasonal effects, with large regional differences.

Trend in heating degree days in the EU-27

Note: Trend in heating degree days in the EU-27 (1980 - 2009). Eurostat calculates heating degree days as (18 °C - Tmean) if Tmean is lower than 15 °C (heating threshold) and zero if Tmean is greater than or equal 15 °C; Tmean is the mean daily outdoor temperature, calculated as Tmean = (Tmin + Tmax / 2)

Data source:

Trend in heating degree days in the EU-27

Note: The map shows the trend in heating degree days in the EU-27 (1980-2009)

Data source:

Data provenance info is missing.

Past trends

The number of heating degree days (HDD) has decreased by 13 % over the last 3 decades, yet with substantial interannual variation (Figure 1). Figure 2 shows that the decrease in HDD has not been homogeneous across Europe. The absolute decrease has been largest in the cool regions in northern Europe where heating demand is highest.


Temperatures in Europe are projected to continue to increase. Hence, the trend of decreasing numbers of HDD is very likely to continue, and most likely to accelerate. For example, the heat demand for space heating in 2050 was projected to decrease by 25 % in the UK [i], and by 9 % in the EU ([ii]).

[i] Martina Flörke et al., Climate Adaptation – modelling water scenarios and sectoral impacts. Final Report Contract N° DG ENV.D.2/SER/2009/0034 (Kassel, Germany: Center for Environmental Systems Research, University of Kassel, Oktober 28, 2011),

[ii] Pre-publication of results from the ClimateCost project (

Supporting information

Indicator definition

  • Trend in heating degree days in the EU-27


  • Heating Degree Days (HDD)/year


Policy context and targets

Context description

In April 2013 the European Commission presented the EU Adaptation Strategy Package ( 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, 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.

Related policy documents

  • Climate-ADAPT: Adaptation in EU policy sectors
    Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
  • Climate-ADAPT: Country profiles
    Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
  • DG CLIMA: Adaptation to climate change
    Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.
  • EU Adaptation Strategy Package
    In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.


Methodology for indicator calculation

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.

Methodology for gap filling

Not applicable

Methodology references



Methodology uncertainty

Not applicable

Data sets uncertainty

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 (

Rationale uncertainty

No uncertainty has been specified

Data sources

Other info

DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CLIM 047
Frequency of updates
Updates are scheduled every 4 years
EEA Contact Info


Geographic coverage

Temporal coverage


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