T. Nikolaou, J. Kapsomenakis, D. Kolokotsa, M. Santamouris and S. Zerefos
Bibliographic info:
Proceedings of the 34th AIVC - 3rd TightVent - 2nd Cool Roofs' - 1st venticool Conference , 25-26 September, Athens 2013

The increase of the ambient air temperatures in urban areas during the past few decades, due to the heat island phenomenon and the warming of the lower atmosphere, has strong impact on the energy profile of buildings, the comfort conditions, the air pollution and the indoor environment, especially in the Mediterranean regions with hot climate conditions. The present paper focuses on the investigation of the impact of the temperature increase in nine Greek cities over the last forty years on the energy demand of buildings. This research is very crucial in order to understand climatic future trends, to establish the development of new technologies and techniques (such as ventilation strategies and smart materials) aiming to reduce the energy consumption of buildings, to improve the urban microclimate, as well as to steer specific policy actions. The methodology developed for this research includes: a) Analysis of climatic data: hourly data series of air temperature and relative humidity covering the forty year period 1970-2010 from nine Greek meteorological stations of the Hellenic National Meteorological Service (HNMS) are presented and analysed. b) Simulation studies: In order to evaluate the potential impact of temperature variation on the energy demand of buildings, specific energy simulation studies have been performed using the Virtual Building Dataset (VBD) tool. The simulation process includes the determination of typical building for the simulations, the development of the required climate data files and the performance of 369 simulations using the VBD tool, which has been developed by coupling TRNSYS with Matlab. c) Analysis of the simulation results: the annual heating and cooling loads of the typical building for the nine Greek cities and for the period 1970-2010. The analysis showed that for the period in question the heating load in the Greek building sector has decreased by about 1 kWh/m2 per decade, while the cooling load has increased by about 5 kWh/m2 per decade. This phenomenon has major environmental, economic and social consequences, which will be amplified in the upcoming decades in view of the expected man-made climatic changes in this geographic area.