STULZ provided the needed help in the form of a cooling and heating installation. The residents chose a hybrid heat pump from Mitsubishi Heavy Industries (FDCW 60 VNX-A with an HSB 60 and RC-HY40, and the RMU40 room thermostat). The heat pump will reduce gas consumption to about 1300 m3 with equal use (that's a saving of 2200 m3). With today's prices, about €1.98 per m3 and €0.47/kW, that saving is about €1325,- which means that after deducting the subsidy (€2700) for the heat pump, there is a Return On Investment period of about 3 to 4 years on this installation!
The savings will be slightly larger because in the bedrooms and office on the second floor there are two Multi Split systems installed consisting of two SCM 40 ZS-S outdoor units, three SRK 20 ZSX-W wall unit and one SRF 25 ZMX-S floor unit. In the summer, of course, cooling can be provided by the air conditioning in the bedrooms and office. The heating of shower water with this system is still controlled from the boiler.