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Heating degree days

Indicator Assessment Created 15 Nov 2012 Published 20 Nov 2012 Last modified 04 Sep 2015, 07:00 PM
Indicator codes: CLIM 047

Key messages

  • 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.

How is climate change affecting the energy demand for space heating across Europe?

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:
Downloads and more info

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:
Downloads and more info

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 (

Indicator specification and metadata

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: Mainstreaming adaptation in EU sector policies
    Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
  • Climate-ADAPT: National adaptation strategies
    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 later. This webportal 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 will enhance 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

Generic metadata


Climate change Climate change (Primary topic)

Energy Energy

Urban environment Urban environment

heating degree | climate change | energy | climate change impacts
DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CLIM 047
Temporal coverage:
Geographic coverage:
Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom

Contacts and ownership

EEA Contact Info

Hans-Martin Füssel

EEA Management Plan

2012 2.0.1 (note: EEA internal system)


Frequency of updates

Updates are scheduled every 4 years
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Phone: +45 3336 7100