In Switzerland there is some neat established method for finding out the needed heating power. Consumption/year x Efficiency / 2000h/year = Max heating power. T

In Switzerland there is some neat established method for finding out the needed heating power. Consumption/year x Efficiency / 2000h/year = Max heating power. This should work for most moderate climates, although you should consult your local climate table. https://pubdb.bfe.admin.ch/de/publication/download/2781 https://pubdb.bfe.admin.ch/de/publication/download/2781 Further even if you undersize your heat pump to only 70% of the max heating power, then you still will get out 99% from your heating from the heat pump on average.