On the variability of summer air temperature during the last 28 years in Athens

[1] The increase of living standards in buildings and the high, summer maximum air-temperature values during the last years have important economic, technical, social, and environmental consequences. Analysis of the summer ambient temperatures is thus necessary to investigate, among others, the important impact on energy consumption. Ambient temperature data from the National Observatory of Athens station for the period 1950–2004 are presented. The number of hours with air temperature above 30°C, as well as the degree hour values (DH) in base of 30°C are estimated and statistically analyzed in order to evaluate passive, hybrid, and conventional cooling systems and techniques. The general conclusion of this study is that during the last 15 years there is a dramatic increase of the number of hours with high air temperatures that leads to an increasing persistence of hot weather conditions. This corresponds, however, to the rising part of the air temperature cyclic change which does not verify yet the estimated significant increasing tendency.