Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Climate impacts on socio-economic systems and healthData quality and data needsData for calculation of HDD have been collected byEurostat for decades; this indicator can thereforebe considered as very reliable. The same dataused could also be used for the calculation ofcooling degree days. Such an indicator is currentlynot available even though it would be highlypolicy-relevant and could be calculated withlittle additional effort. It should be noted that theindicator HDD is a purely physical metric, whichdoes not consider differences in technical, social andeconomic factors (housing quality, behaviour, prices,etc.) between regions and their development overtime.Information on past and projected impacts ofclimate change on electricity demand and electricitygenerator output is very fragmented. The signalof long-term climate change may be difficult todetect due to concurrent changes in technical,social, behavioural and economic aspects, whereasthe effects of extreme events are generally easier todetect.4.5.2 Heating degree daystherefore a proxy for the energy demand for spaceheating, and hence an indicator for possible changesin overall energy use directly related to climatechange.An increase in cooling demand would off-setin part or completely the gains from a reducedenergy demand for space heating and the effectsresulting from a reduction in heating demand. Whileheating is delivered to end users in different ways(individual boilers fuelled by oil, gas, and coal, andelectricity and district heating), cooling is deliveredcurrently almost exclusively through electricity.As a result, a given increase in cooling demand isgenerally associated with higher costs, a higherincrease in primary energy demand and largerimpacts on the peak capacity of supply networksthan the same decrease in heating demand.Past trendsThe number of HDD has decreased by 13 % overthe last 3 decades, yet with substantial interannualvariation (Figure 4.9). Map 4.16 shows that thedecrease in HDD has not been homogeneous acrossRelevanceA 'Heating Degree Day' (HDD) is a proxy forthe energy demand needed to heat a home or abusiness; it is derived from measurements of outsideair temperature. The heating requirements for agiven structure at a specific location are consideredto be to some degree proportional to the number ofHDD at that location. However, they also depend ona large number of other factors, notably in relation toincome levels, building design, energy systems andbehavioural aspects. HDD are defined relative to abase temperature ( 67 ), the outside temperature belowwhich a building is assumed to need heating.Space heating is responsible for a large componentof European energy use, so a decrease in the useof space heating has the potential to lead to asignificant decrease in overall energy use. There aremany contributory factors to heating demand, suchas the energy performance of the building envelope,the type of heating system available, occupantbehaviour and energy prices. However, the externaltemperature is the only component which is directlyaffected by climate change. The number of HDD isFigure 4.9Heating degree days3 8003 6003 4003 2003 0002 800198019821984Source: Eurostat, 2012.Trend in heating degree days inthe EU-27 (1980–2009)Heating degree daysLinear trend198619881990199219941996199820002002200420062008( 67 ) 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 greaterthan 15 °C, where Tm is the mean (Tmin + Tmax/2) outdoor temperature over a given period of d days.202 Climate change, impacts and vulnerability in Europe 2012