Numerical assessment of heating energy demand for office buildings in Italy

Buildings energy consumption depends on several parameters, such as climate, envelope typologies, occupant behavior, intended use, etc.; assessment of the energy performance of a building requires substantial input data describing constructions, environmental contexts, thermo-physical properties, geometry, control strategies and several other parameters influencing the thermal balance. In the last years, several numerical approaches dedicated to building simulation have been tested developing specialized software. On the other hand, simplified building models permit the evaluation of indoor conditions and heating/cooling loads with a good level of accuracy and without excessive computational costs or user expertize. The authors tried to establish a set of simple correlations to permit a fast preliminary assessment of heating energy demand for office buildings. Data employed to build the correlations come from detailed dynamic simulations performed in TRNSYS 17 environment; these models were build according to the legal limits of Italian standards and laws concerning low energy requirements. The authors identified specific locations for different Italian climatic zones and simulated three models with different shape factors (S/V = 0.24, 0.5 and 0.9). The obtained results allowed to determine simple and direct correlations among heating energy demand, Heating Degree Days and S/V values.