Meaningful energy concept for new Kfw70 construction without oil or gas

Hello, I would like to be (more) independent from rising energy costs.

You should write the flow temperature and explain why a gas heating system is a problem for you. Then one could address the question better. Because in principle, a gas heating system does make sense.

Sorry, I overlooked your info

Doesn't everyone want to be independent? Ultimately, it’s a matter of price: what additional technology can I afford to be self-sufficient. But you will always be dependent on electricity.
You first have to pay off the investment

We are currently heating with a split air conditioning unit powered by photovoltaic electricity. The air conditioner initially requires about 900 W, but then quickly reduces to 300 W once the target temperature is reached and eventually turns off by itself. It heats up immediately, similar to a fan heater, as the warm air is blown directly into the room. The photovoltaic system easily provides the maximum 900 W during the day even in winter, unless we have persistent fog again. The heat then lasts long enough in a well-insulated house. Since it is an air conditioner with "heat pump technology," it produces at least 3 kWh of heat from 1 kWh of electricity. At 14 ct/kWh electricity (photovoltaic electricity!!), that is about 4.5 ct per kWh of heat; it hardly gets cheaper than that. The device does not require radiators or pipes; the installation cost was 400 euros for complete installation, and the 3.7 kW unit was purchased with a 20% discount off the retail price at Metro—for 571 euros. In summer, it cools—there really is no better way to use self-generated electricity. Additionally, it reduces humidity and thus prevents mold. However, if you still want warm feet, you cannot avoid another solution that also allows for underfloor heating. We have both a (pellet) boiler, a split air conditioning unit—and additionally a wood stove.

I think it rather means: a maximum of 3 kWh heat from one kWh of electricity at this price range! Especially in winter with cold outside air, I expect a significantly lower efficiency. Moreover, warming the building envelope with warm air is difficult due to the low heat capacity, particularly the distribution over several rooms. The comfort temperature with air heating is otherwise higher than when heating the envelope. As a "solo" device, it is therefore usually quite impractical.

Air is a very very inert energy carrier or the most inert one if I am not mistaken...

We decided on a ground source heat pump with ground collectors for heating and an air/water heat pump for hot water demand, but this one is installed in the utility room where it uses all the heat from the room (the heating circuit distributor of the underfloor heating is located in that room, so every heated room starts there, which releases a lot of heat, plus the electrical devices like the condenser dryer, for example, which also releases a lot of heat)

Electricity companies have liked to advertise air heat pumps for a while (or are they still doing it?), because they consume the most electricity, which benefits them

I would rather slap solar thermal on the roof, it not only uses pure sunlight like a photovoltaic system but also draws heat from the air and rain... but it is also more expensive to purchase (photovoltaic prices have dropped a lot recently)

How about a pellet stove?

I am not a friend of gas either, but that has more to do with the fact that, as a firefighter, I am not very fond of gas

Air is a very, very sluggish energy carrier or the most sluggish one if I am not mistaken...

Actually, air takes on temperature very quickly. However, air can only transport small amounts of energy. That’s probably what you mean.

We decided on a geothermal heat pump with ground collectors for heating and an air/water heat pump for hot water supply; however, this one is installed in the utility room where it uses all the heat from the room (the heating circuit distributor for the underfloor heating is located in that room, so every heated room starts there, which emits a lot of heat, plus there are electrical appliances like a condenser dryer that also emits a lot of heat)

How did this unusual setup come about? Why don’t you also have the more efficient geothermal heat pump prepare the hot water?

In which region will the house be located? Air-to-air heat pumps should only be used in better KFW55 houses/passive houses with minimal heat demand. KFW70 actually sounds quite suitable for a brine heat pump. We live in a fairly cold region in Germany, also have Kfw70 and just over 200 sqm (including basement) heated – underfloor heating everywhere. The consumption fits – unlike some air heat pumps here in the new development area. However, unlike gas, you have to deal somewhat with the heat pump to have an optimized system – and especially a heating engineer with experience (no buffer storage, no individual room control, etc.). On the topic of controlled residential ventilation, there are enough pro/con contributions to form an opinion. We have installed one. By the way: brine heat pump AND air heat pump... – how is that? Also, heating circuit distributors should be insulated. In a reasonably modern utility room, there is no waste heat anymore – except from the clothes dryer. Regards