ᐅ Effective Energy Strategy for New Construction KfW70 Without Oil or Gas

Hello,

we are planning to build within the next 1-2 years, approximately 170-190 sqm (1830-2045 sq ft) for 5 people, meeting the KfW 70 standard. We definitely do not want gas or oil heating.

We are considering an air-to-air heat pump with automated ventilation for the house, including heat recovery and domestic hot water heating using waste heat (as seen from a prefabricated house supplier).

Since heating with electricity can be expensive, we would like to combine this system with a photovoltaic (PV) installation.

What do you think about this? How do the initial investment and running costs compare to a conventional heating system?

As additional options, I am also thinking about solar thermal and a wood stove (with a heat storage unit?), but I am skeptical about whether these can be integrated smoothly. Of course, it should also be economically viable in the medium term.

Regarding initial costs, you have chosen the most expensive option. You are installing almost everything into your house that is available aside from gas and oil. The photovoltaic system then produces the least electricity when you need it most: during winter.

From many discussions about mechanical ventilation with heat recovery ("controlled residential ventilation and heat recovery"), the general consensus is that this technology is for comfort (if you appreciate this kind of comfort), but it never pays off financially.

Air-to-air heat pumps consume a lot of electricity in a large house, require annual maintenance, and are complex devices. Personally, I am not a fan of them, but that is more a matter of belief, which I do not want to debate here again.

Why no gas? For ecological reasons?

klblb schrieb:
Why no gas? For environmental reasons?

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

The technology you listed requires a huge amount of electricity. This makes you just as dependent on energy costs. You might want to look at the price trends for electricity over the past 15 years. No one expected these changes, including the fact that oil is currently very cheap because the USA produces its own demand entirely (and even partly exports) while the global economy is stagnating and therefore consuming less. The gas price is linked to the oil price. Political factors such as the energy transition and the broader geopolitical climate are completely unpredictable.

Personally, I believe energy prices are too uncertain to base the decision for one energy source or another in a house solely on forecasts.

OK, then let’s leave out the air-to-air heat pump with controlled ventilation.

What would you consider useful from the rest? Would a piecewood fireplace (with heat storage) for winter and solar thermal for summer be enough for heating and domestic hot water? Or is the gas connection absolutely necessary?

You should explain why a gas heating system is a problem for you. That way, it would be easier to address the question. After all, a gas heating system is fundamentally a reasonable option.