Effects of Climate Change on the Energy Required for the Treatment of Ventilation Fresh Air in HVAC Systems the Case of Athens and Thessaloniki

Abstract

All current observations as well as projected changes suggest an increase of ambient air temperature, especially in large urban areas. The energy consumption for ventilation will be affected by the impacts of this change in climate because ventilation loads are varying directly with the local ambient temperature and humidity conditions. This is very important in urban areas because mechanicalventilation systems, which consume significant amounts of energy, are installed in most of the buildings of the tertiary sector.In planning the ventilation of a building, the ventilation air supplyand the energy that will be consumed should be known to the designer of the HVAC system from the initial stages of the task, in order to estimate the operating costs of the system. A user-friendly toolfor estimating the ventilation energyrequirements is the “ventilation load index (VLI)”. In this work, an analysis that shows the changes of the VLI during the last three decades (1983-2012) for the two largest cities in Greece, namely Athens and Thessaloniki, is presented. Using appropriate calculation formulasand climatic data,VLIin heating and cooling period,and for 8, 16 and 24-hour operation periods of ventilation systemis calculated. The results are synoptically presented in tables and diagrams. The study shows that the energy demands in cooling period are increased, more intensively during nighttime, and in heating period are decreased. However, the total ventilation energy demandson a yearly basis are decreased from decade to decade.