Energy performance of buildings: comparison between a dynamic model and a normalized method.

The European directive 2002/91 introduces some modifications regarding energy performance of buildings as well as of HVAC systems. Buildings are to be thought as “containers” where, by a careful planning of the envelope and plants within, the designer must foster indoor comfort conditions. These needs, together with the growing increase in the cost of energy, have led to a modification of the energy scenarios. The integration between HVAC systems and building envelope has now to meet both the requirement of higher life standards and the reduction in energy consumption. The present work develops a dynamic model, employing DesignBuilder, a code in Energy Plus environment, for the evaluation of the primary energy needs. DesignBuilder allows modelling buildings in 3D space environment. Moreover, it contains a rich database with many different materials and European climate information. It also allows changing of significant part of buildings. The annual heating requirements have been evaluated for different building typologies, which are characterized by a variable number of floors and different values of the ratio between the dispersing surface and the volume. The analysis has been conducted on constructions placed in Bologna, in the north-centre of Italy. The results are compared with those obtained applying the European Standard method.