A renewable energy concept featuring a brine-water heat pump, a horizontal ground-source heat collector, underfloor heating with passive cooling, a 1,000-litre buffer tank and a photovoltaic system was implemented for a newly built detached house in Meissen.
Particular mention should be made of the simulation-based planning: using a dynamic building and system simulation, the heating load, heating energy demand and load profiles were determined with precision. This made it possible to size the heat pump and ground collector to be around 50 per cent smaller than in a conventional design. In addition, the operation of the heat pump is specifically shifted to the sunniest hours of the day – achieved, amongst other things, through night-time temperature reduction, adjusted heating curves and optimised buffer storage management. As a result, the proportion of the heat pump’s operating time covered by daytime – and thus renewable – energy was increased from around 23 per cent to almost 98 per cent. Monitoring of the system in 2020 shows a total heat demand of around 12.4 MWh per year (62 kWh/m²a) and an annual coefficient of performance (COP) of 4.2 for heating and 3.1 for domestic hot water heating. Of the approximately 10.3 MWh of PV electricity generated annually, around 3.55 MWh could be used directly. This corresponds to a self-sufficiency rate of around 49 per cent and is thus significantly higher than that of comparable PV-heat pump systems without load optimisation. The high level of self-consumption significantly reduces running costs – both compared with conventional PV-heat pump systems and compared with a gas condensing boiler combined with solar thermal.
