Study of heating and cooling systems to design zero energy buildings

By 2020 all new buildings within the European Union should reach nearly zero energy levels. Their energy needs should be significantly covered by renewable energy sources. As a consequence, it is important to identify which combinations of technologies will be suitable in order to reach such objectives. Climate conditions, final energy and investment costs, technological maturity and stakeholders’ services quality are key elements for the final choice. This paper presents the first results of a more general survey the purpose of which is to study different combinations of heating - cooling systems integrated in single-family dwellings under the Belgian climate conditions. Eight representative dwellings and one heating system composed of solar collectors and an air-to-water heat pump were selected. The dwellings were chosen in such a way that different insulation levels may be studied: we considered houses with an insulation level that just respects the 2008 EPBD legislation (arête du gouvernement wallon, 2008) as well as very low energy houses. The heat pump and solar collectors are connected to a heat storage water tank as well as to a DHW reservoir.  A design procedure based on energy needs is proposed and applied to each dwelling-system. The design characteristics of the system are then integrated in a simulation software (TRNSYS 17) to perform a one-year energy performance calculation (Klein, S.A, et al.,2000). The results show that the solar coverage ratio for DHW production ranges from 52% (very low energy buildings) to 76% (EPBD buildings). The solar coverage ratio for space heating ranges from 3% (very low energy buildings) to 9% (EPBD buildings). Whatever the kind of building, the seasonal performance factor of the heat pump is about 3.45. The total non renewable primary energy that is used is about 57% of the total heat demand.