A German company active in technical building services has designed its new head office building with a very innovative energy concept, combining photo-voltaic electricity generation, solar/air absorbers, a R-410A heat pump, and a water/ice storage tank.
Electric power generated by 320 m2 photovoltaic panels is used to power the heat pump and covers the building energy usage.
The R-410A heat pump has a heating capacity of 100 kW and a cooling capacity of 73 kW, with a COP of up to 4,9 and a maximum heating temperature of 60°C. Together with 380 m2 solar/air absorbers, it delivers warm water for heating the building, through a system of pipes embedded in the ceilings of the concrete structure.
Key of the system is a 350 m3 storage tank, located under the parking lot, which is used as heat source for the heat pump, and contains as heat exchanger 5,700 m of closed-loop water piping. During the heating phase heat is drawn from the tank water, causing ice to form on the piping, but energy provided from the roof absorbers melts the ice again, creating an infinite heat source for the heat pump.
The tank is also used as heat buffer between the summer and the winter. At the end of the heating period, it is almost full of ice, and in the warm season the produced ice is used to cool the building. Ice formation or melting allows to store or release large quantities of energy, keeping the size of the buffer tank moderate.