Sustainable criteria for design of buildings: an innovative case-study of high efficiency building in Italy

The design of buildings following sustainable criteria comprehends several aspects focusing on a worldwide vision of rational energy use. From this point of view lowering HVAC energy demand and pollutant emissions are fundamental. These targets can be reached by using renewable energy sources or high efficiency heat pumps and chillers, and by the adoption of bio-materials. This paper describes the design study underlying three sustainable buildings under construction in Arzignano (Vicenza), Italy. These buildings are characterized by an energy efficient HVAC system, and an high-insulation building envelope. The building has a net air-conditioned and heated area and volume of 310 m2 and 830 m3 respectively. The envelope opaque components are designed according to national law criteria, the thermal transmittance towards external environments are lower than 0.30 W/(m2•K); the windows have a U-value lower than 1.5 W/(m2•K) (two-panes glasses with Argon cavity gas). These values are obtained adopting innovative and bio-sustainable materials like the foam-glass. The heating/cooling system consists in an air-to-water heat pump coupled with a floor radiant system and a mechanical ventilation system provided with an active energy recovery from exhaust air coupled with a earth-to-air heat exchanger. The building solar passive characteristics have also been considered in the design phase to allow the highest heat gains during wintertime while the summer overheating is controlled by shading systems. The resulting envelope energy demand is 25 kWh•m-2 and 9 kWh•m-2