ᐅ New construction KfW55 energy standard with gas heating, solar panels, and controlled ventilation system with heat recovery

Hello!

We are just starting the planning of our new build, and the big question we keep discussing is the heating system.
We are building a detached single-family house with 145 sq m (1560 sq ft) plus an expanded attic of about 40 sq m (430 sq ft) with underfloor heating (including in the attic).
We want to achieve KfW55 standard. The house will be built with solid masonry and brick veneer.
One thing we definitely want is a controlled ventilation system with heat recovery.
The most cost-effective option so far seems to be a combination of gas, solar thermal, and ventilation. The construction companies we are requesting quotes from are also offering a KfW55 package with improved insulation, as it might be difficult to meet the required standards otherwise.
An alternative (the second most affordable option) would be an air-to-air heat pump instead of gas.
What are the advantages and disadvantages of these two heating systems? What would the approximate expected monthly costs be?
Some heating installers have told us that achieving KfW55 with gas is not possible at all.
We are quite confused, and everyone says something different.
What are your experiences?

Thank you very much!

Is KfW55 mandatory because of funding or other reasons?

We had the option of gas with a storage tank or a heat pump.

Insulation was similar for both, and controlled mechanical ventilation with heat recovery was mandatory in both cases.

KfW 55 with gas, solar support, and controlled ventilation with heat recovery is possible and is even mentioned in the reference process for the KfW calculation.
Your heating installers apparently are not familiar even with the brief KfW information sheets.
Besides, the energy consultant is the one who performs the calculations, and the heating installer should only supply and install the system.

Air-to-air heat pumps do not have a good reputation here, which seems understandable to me. Take a look in the search function.

Are you sure it’s an air-to-air heat pump you mean? The direct alternative to gas is usually an air-to-water heat pump.

Thank you for your responses!

I meant air-to-water heat pump—sorry! With all the abbreviations, I don’t always keep up yet.

According to the KfW information sheet, I understood that this is also a common way to achieve the 55 standard.
But then we got really unsettled because everyone so far has told us that it would be rather difficult with gas.

Now we definitely won’t let ourselves be stressed anymore and will calmly wait for the energy consultant’s opinion.

Thanks again!

Regards,
Xenia