Our heat pump Alpha Innotec WZSV 62K3M costs €12,094.67 net including installation and commissioning. The controlled residential ventilation Maico WS 320KB also costs €6,897.44 net including installation. However, we carried out the controlled residential ventilation piping from the air distributors ourselves (it’s not rocket science). Additionally, there is a drilling of 110m at €5,280 net since it is a brine-water heat pump. We expect tolerable temperatures even in high summer through the PC (PassiveCooling) option as well as wall/roof construction with material that each offers high summer heat protection, and suitable shading by Venetian blinds on all windows.
And of course, there is no “the” heat pump and also no “the” only correct controlled residential ventilation system; a specialist (preferably also an energy consultant + plumber) has to deal with it and perform suitable sizing. From hearsay, often significantly oversized heat pumps are installed, which apparently is detrimental to efficiency and lifespan. Even if you plan to install an air conditioning system, I would not neglect the points of shading and building materials regarding summer heat protection. Investments in the above points are one-time; air conditioning always consumes electricity (costs). Even with your own photovoltaic system (not earned feed-in tariff is equal to spent money) ;)