PROGETTARE L'EFFICIENZA ENERGETICA: esperienze sul ruolo del sistema edificio, del sistema impianto e della loro gestione

The present study deals with the issue of energy efficiency in buildings, considering that the choice of the optimal solution can be performed only starting from a joint design of all systems and technologies available, and bearing in mind that the final goals are the pursuit of the user’s overall wellbeing, energy saving and building functionality with respect to its intended use. For this reason, a set of issues have been investigated, very different from one another but that allowed for a wider perspective on the various aspects to be taken into account for a suitable and integrated design and for their interaction. Every experience encountered plays a different and specific role in defining the key-points of an integrated design, i.e. reducing thermal energy demands for heating, cooling and lighting purposes by acting on the whole building; reducing primary energy consumption by adopting highly efficient building services; maximizing the use of renewable energy sources to cater for electricity and thermal energy demands; optimizing the energy performance of buildings by using automated control and regulation systems and by setting a suitable building management and maintenance program. More specifically, Section 2 deals with the role of passive solar systems in reducing thermal energy demands when different constraints (morphological, urban planning and architectural ones…) existed, for the energy retrofit of both existing and newly built constructions. In Section 3 simplified models for the analysis of heat generators, with specific reference to the two Methods defined by UNI TS 11300-2 technical standard are examined. Section 4 explores the role of renewable energy sources. In particular, is described a hot water equipment supplying a hospital complex in the province of Milan, consisting of a gas-fired heat generator, a solar thermal plant and a heat pump extracting low temperature energy from groundwater intended for technical use, i.e. to preheat domestic water supplied by the water purification system. Finally, in Section 5 the role of building management is discussed. In particular, heat accounting systems and methods for the compensated share of heating expenses are analysed.