Which heating system should be installed in a household with 2 and later 4 people?

Hello everyone, I have already read through many things and am even more confused now... We are a couple, 27 years old, and want to build, using prefabricated construction. We have researched the companies and sorted everything thoroughly, and it will be a Kfw 40 house. Now the question about the heating comes up, because everyone tells me something different, whether these people have already built, are currently building, or want to sell something (prefabricated house manufacturers). Which heating system should we install for a household of 2, later a maximum of 4 people? It is about 160-170 sqm of living space and two full floors with a city villa. There would be no shading, and we have planned an almost square house. Most say we should just make it 40+ and build an air-water heat pump with a photovoltaic system and storage. Now someone said that with such a house, the photovoltaic system with storage is not worthwhile at all, as it would never pay off... Can someone please help me?????

Unfortunately, the jack of all trades doesn't exist as a heating system either; you'll have to swallow a toad.

A gas boiler, for example, is very affordable and in a well-insulated house with possibly central ventilation, you really need very little. So if you focus on the heating system paying off quickly, then that is the choice. Unfortunately, these are fossil fuels and then Kfw 40 or 55 is no longer feasible...

If you prefer a good KfW rating instead of quick amortization, then size your photovoltaic system so that you live almost self-sufficiently. Heating with the energy you generate yourself and then also storage. Since storage is currently (still?) very expensive, you can also do it so that you size the photovoltaic system large enough and initially do without storage and possibly still draw electricity from the grid and later, when the storage hopefully has become cheaper, retrofit storage. How that affects the KfW rating, I do not know.

It is simply like this: either I have a high-quality system that enables me to live an almost self-sufficient, ecologically justifiable lifestyle, or I have a system that pays off as quickly as possible. Somewhere in between you probably have to find your salvation.

Many options are feasible and each has its own advantages.

I'll jump in here, they'll probably build in a similar size and the same design (just solid). I'm also quite at a loss when it comes to heating and find it very difficult to figure out what would be right for us (also for 4 people later). I would also be interested in the maintenance aspect and space requirements. With which systems does a filter need to be changed constantly or does someone have to perform maintenance, how long do the different systems last, and which are particularly space-intensive (especially interesting if built without a basement)?

In well-insulated houses and with underfloor heating, a heat pump is usually recommended since high flow temperatures are not required. In that case, you are basically heating with electricity, which can be compensated by appropriate photovoltaic equipment on the roof. Possibly additionally a solar thermal module for charging the buffer tank, so even less electricity is consumed. Heat pumps are somewhat more expensive to purchase, but there are also subsidies, e.g. from [BAFA]. The more efficient the house is, the more economical a ground-source heat pump becomes, as the area requirement or drilling depth for the heat source naturally also decreases. This reduces the collector costs while the subsidy remains the same (in our case [4,500€] from [BAFA] for a ground-source heat pump with [Smart Grid] certification and buffer tank). This covers the costs for the collector completely.

I'll put it this way... the more complicated the system becomes, the longer you have to wait, and the more expensive the maintenance gets. Because it takes longer. That's why I think proposals like: ...here another storage unit... and here another photovoltaic system... and some solar thermal on the roof too, so the house practically heats itself...

are absolutely worthless... and I wouldn't let anyone install something like that in a single-family house either. It will be a regulatory nightmare and the investments are not insignificant... and as I said, the maintenance will also increase. The system should be simple and efficient, not just a miscellaneous collection of everything available, just because there are subsidies, etc.

We simply have a condensing boiler and hot water support through photovoltaics..That’s how I am in energy efficiency class A and that’s good...