Heating and cooling degree days

Assessment versions

Published (reviewed and quality assured)

• No published assessments

Rationale

Justification for indicator selection

Space heating and cooling is responsible for a large fraction of European energy use. Heating degree days (HDDs) and cooling degree days (CDDs) are proxies for the energy demand needed to heat or cool, respectively, a home or a business. Both variables are derived from measurements of outside air temperature. The heating and cooling requirements for a given structure at a specific location are considered, to some degree, proportional to the number of HDDs and CDDs at that location. However, they also depend on various other factors, such as building design and insulation, availability and type of heating and cooling systems, energy prices and income levels, and behavioural aspects.

A decrease in the demand for space heating can significantly decrease overall energy use in Europe, but this gain can be offset in part or completely by an increase in cooling demand. Furthermore, heating is delivered to end users in different ways (individual boilers fuelled by oil, gas and coal, and electricity and district heating), whereas cooling is delivered currently almost exclusively through electricity. As a result, a given change in cooling demand is generally associated with larger costs, a larger change in primary energy demand and larger impacts on the peak capacity of supply networks than the same change in heating demand.

Scientific references

• IPCC, 2014a: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1132 pp.
• IPCC, 2014c: Europe. Kovats, R.S., R. Valentini, L.M. Bouwer, E. Georgopoulou, D. Jacob, E. Martin, M. Rounsevell, and J.-F. Soussana, 2014: Europe. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1267-1326.

Indicator definition

• This indicator looks at the following:
• Time series of population-weighted heating and cooling degree days averaged over Europe;
• Observed trends in heating and cooling degree days;
• Projected trends in heating and cooling degree days.

Units

• The units used in this indicator are heating and cooling degree days (° C*d/yr)

Policy context and targets

Context description

In April 2013, the European Commission (EC) presented the EU Adaptation Strategy Package. This package consists of the EU Strategy on adaptation to climate change (COM/2013/216 final) and a number of supporting documents. The overall aim of the EU Adaptation Strategy is to contribute to a more climate-resilient Europe.

One of the objectives of the EU Adaptation Strategy is 'Better informed decision-making'. This shall be achieved by bridging the knowledge gap and further developing the European climate adaptation platform (Climate-ADAPT) as the ‘first-stop shop’ for adaptation information in Europe. Climate-ADAPT has been developed jointly by the EC and the EEA to share knowledge on (1) observed and projected climate change and its impacts on environmental and social systems and on human health; (2) relevant research; (3) EU, transnational, national and sub-national adaptation strategies and plans; and (4) adaptation case studies. It was relaunched in early 2019 with a new design and updated content. Further objectives include 'Promoting adaptation in key vulnerable sectors through climate-proofing EU sector policies' and 'Promoting action by Member States'.

Most EU Member States have already adopted national adaptation strategies and many have also prepared action plans on climate change adaptation. The EC also supports adaptation in cities through the Covenant of Mayors for Climate and Energy initiative.

In November 2018, the Commission published its evaluation of the 2013 EU Adaptation Strategy. The evaluation package includes a Report from the Commission, a Commission Staff Working Document, the Adaptation preparedness scoreboard country fiches, and the reports from the JRC PESETA III project. This evaluation includes recommendations for the further development and implementation of adaptation policies at all levels.

In November 2013, the European Parliament and the European Council adopted the 7th EU Environment Action Programme (7th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7th EAP refer to climate change adaptation.

In February 2016, the Commission published an EU Strategy on Heating and Cooling, which aims to decarbonise the heating and cooling of buildings through different technologies and measures, in line with wider EU climate and energy policies.

Targets

No targets have been specified.

Related policy documents

• 7th Environment Action Programme
  DECISION No 1386/2013/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. In November 2013, the European Parliament and the European Council adopted the 7 th EU Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. This programme is intended to help guide EU action on the environment and climate change up to and beyond 2020 based on the following vision: ‘In 2050, we live well, within the planet’s ecological limits. Our prosperity and healthy environment stem from an innovative, circular economy where nothing is wasted and where natural resources are managed sustainably, and biodiversity is protected, valued and restored in ways that enhance our society’s resilience. Our low-carbon growth has long been decoupled from resource use, setting the pace for a safe and sustainable global society.’
• 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.
• Evaluation of the EU Adaptation Strategy Package
  In November 2018, the EC published an evaluation of the EU Adaptation Strategy. The evaluation package comprises a Report on the implementation of the EU Strategy on adaptation to climate change (COM(2018)738), the Evaluation of the EU Strategy on adaptation to climate change (SWD(2018)461), and the Adaptation preparedness scoreboard Country fiches (SWD(2018)460). The evaluation found that the EU Adaptation Strategy has been a reference point to prepare Europe for the climate impacts to come, at all levels. It emphasized that EU policy must seek to create synergies between climate change adaptation, disaster risk reduction efforts and sustainable development to avoid future damage and provide for long-term economic and social welfare in Europe and in partner countries. The evaluation also suggests areas where more work needs to be done to prepare vulnerable regions and sectors.

Methodology

Methodology for indicator calculation

HDDs and CDDs are defined relative to a base temperature — the outside temperature — below which a building is assumed to need heating or cooling. They can be computed in different ways, depending, among other things, on the specific target application and the availability of sub-daily temperature data. Previous versions of this indicator published before 2016 applied the methodology of Eurostat, which uses daily mean temperature only and has a jump discontinuity when daily mean temperature falls below the base temperature. This indicator uses an approach developed by the UK Met Office, which uses daily mean, minimum and maximum temperatures and does not exhibit a discontinuity. Note that this approach, being based on both minimum (T_n) and maximum (T_x) temperatures and not solely on the mean temperature (T_m), increases the accuracy of HDDs and CDDs for the purpose of gauging the impacts of climate change on energy demand, because the cooling of the environment depends more on T_x than on T_m, while T_n is more relevant for heating. The baseline temperatures for HDDs and CDDs are 15.5 °C and 22 °C, respectively. As a result of the methodological changes, the magnitudes of the trends between this version of the indicator and versions published before 2016 cannot be directly compared.

The aggregation of regional changes in HDDs and CDDs to larger areas can be done using area weighting or population weighting (with a fixed population). Population weighting is preferable for estimating trends in energy demand over large regions with an uneven population distribution, such as Europe.

Methodology for gap filling

Not applicable

Methodology references

• Spinoni et al., 2015: European degree-day climatologies and trends for the period 1951–2011. Spinoni, J., Vogt, J. and Barbosa, P., 2015, 'European degree-day climatologies and trends for the period 1951–2011', International Journal of Climatology 35(1), 25–36 (DOI: 10.1002/joc.3959).
• Spinoni et al., 2018: Changes of heating and cooling degree-days in Europe from 1981 to 2100. Spinoni, J., et al., 2018, 'Changes of heating and cooling degree-days in Europe from 1981 to 2100', International Journal of Climatology 38, pp. e191-e208 (DOI: 10.1002/joc.5362).

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• European degree-day climatologies and trends for the period 1951–2011 (Dataset URL is not available)
• EURO-CORDEX Data
• Changes of heating and cooling degree‐days in Europe from 1981 to 2100
• E-OBS gridded dataset
• GEOSTAT 2011 grid dataset

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

The climatological input data sets for computing past trends for HDDs and CDDs in Europe combine temperature data with daily resolution from three different station data sets — the JRC’s MARS meteorological database, the NOAA National Climatic Data Center (NCDC)’s Global Historical Climatology Network data set and the European Climate and Assessment Dataset of the Royal Meteorological Institute of the Netherlands — and from one gridded data set (E-OBS versions 17). The resulting trends are considered robust in most regions, but there are open questions for some regions with poor station coverage.

HDD and CDD projections are derived from the ensemble mean of 11 high‐resolution bias‐adjusted EURO‐CORDEX simulations. Climate simulations are associated with uncertainties related to the underlying emissions or forcing scenario, natural variability and model uncertainty. However, temperature is generally simulated better than other climate variables, and the use of multi-model averages and of bias adjustment further reduces errors in individual simulations.

Different definitions exist for computing HDDs and CDDs, which can lead to different magnitudes of calculated trends.

Rationale uncertainty

No uncertainty has been specified