Swiss national project

Switzerland has a strong growth in low energy houses since the introduction of the voluntary MINERGIE^® label in 1998. Presently, about 25% of the new buildings are certified according to MINERGIE^® and about further 15% are not certified, but comply with the MINERGIE^® requirements.
In 2002, the MINERGIE-P^® label, defining an ultra-low energy house, has been introduced, and in 2006, the MINERGIE-ECO^® label followed, which considers besides energy and comfort as well health and sustainablility aspects of the building materials.
In 2011, the MINERGIE-A^® label is introduced, which defines a highly efficient building with near zero energy consumption.
In Switzerland heat pumps are the market leading heating system in new single family dwellings, reaching a share of about 70% in 2005 and 2006. (Fig. 1).

Fig.1   standard hydronic layout for a ground-coupled heat pump system with passive cooling option and simultaneous space cooling           - DHW production

The Swiss national project is dedicated to the integration of a cooling function in heat pump systems for low energy houses. As result, typical system configurations for space heating/-cooling and DHW production, eventually coupled to a mechanical ventilation system, are derived.
Background of the project is an increased interest of space cooling options in residential dwellings. However, there are still insecurities about the hydraulic configuration, the operation limits, reachable comfort as well as system performance and adequate control strategies. Favourable for the application are marketable system configurations already containing a heat pump and further components which can be used for a pre- and passive cooling in summertime. These passive cooling opportunities should be deployed first and active cooling with a reverse operation of the heat pump should only be used to cover peak loads, if necessary, in order to minimize additonal energy consumptions. On the other hand, active cooling can also have a high performance when applied in simultaneous operation with DHW. Five basic typical system configurations and component variants have been derived and are investigated in simulations. Objective of the project is to derive a simple and robust hydraulic configuration of the system and design for the chosen system configurations. Results of the system comparison are documented in the field monitoring report.
In parallel, two field tests of ground-coupled heat pump systems with included passive cooling functions have been accomplished. One system is installed in a multi-family house according to the Swiss ultra-low energy house standard MINERGIE-P® and the other in a single family house according to MINERGIE®. In focus was the functionality and performance of the the passive cooling operation. The results of the field test are presented in two Best Practice Sheets and the field monitoring report.

The Swiss activities are supported by the Swiss Federal Office of Energy (SFOE)