Heating degree-days over Greece as an index of energy consumption

The geographical distribution of heating degree-days (HDDs) in Greece is studied by means of special maps. HDDs are calculated by using daily thermal parameters (daily maximum and minimum air temperature) and then compared with an experimentally determined basic air temperature equal to 14degreesC, according to our estimations. These calculations are based on daily weather data of 40 meteorological stations of the Hellenic National Weather Service published in the Monthly Climatic Bulletin. The regionalization of the 40-point stations' data was achieved using the multiple regression analysis technique and a digital terrain model. For the statistical analysis, the calculated HDDs provide the dependent variables, and geographical data of latitude and longitude, elevation, nearest grid distance from the sea and the land/sea ratio were the independent variables. The resultant statistical correlation was very high. The final outcome of this study was the drawing up of 10 HDD maps, eight for the eight coldest months (October to May) in Greece, one for the entire cold period and one for the number of days demanding heating. The geographical distribution of HDDs is consistent with the great variety of Greek climates arising from the influence of the country's variable relief. The distribution of the HDDs presented in the maps shows that the calculated values were close to the measured ones, which confirms the accuracy of the statistical model used. Possible small deviations were deemed to be acceptable, as the net of the stations used is sparse and it is limited to the elevations below 700 m above sea level. The high accuracy of the HDD maps will be useful for various energy projects and other environmental applications. Copyright (C) 2004 Royal Meteorological Society.