ᐅ KfW40 house offer with heat pump and mechanical ventilation with heat recovery— is it worth it?

Hello everyone,
Today I received a house offer from a prefabricated house supplier.
They list the exhaust air heat pump Nibe F 750 with supply air module SAM 40 as the heating system. The maximum building heating load is said to be 7.5 kW.
Additionally, there is underfloor heating and a 180 L (48 gallon) domestic hot water storage tank.
The house is located near Cologne/Bonn Airport (for climate reference) and is about 120 m² (1,290 sq ft) in size (excluding the basement).

I have already read a lot of negative things about exhaust air heat pumps, so I want to ask again if this system is any good, and if not, what would be an alternative and how much more would that cost?

Thank you very much!

Should the 7.5 kW be the heating load of the house? If so, I find that far too high for KfW 40 standard... If the 7.5 kW refers to the heating load that the heat pump can handle, I would also be cautious that this isn’t just marketing from the house sales department.

I assume that it refers to the building, as it reads that way in the quote.

Hardly any single-family home provider gives you a usable heating load calculation during the offer phase.

7.5 kW is far too high for 120 m² (1,292 ft²) KfW 40.

Exhaust air heat pumps are only suitable for passive houses. Please do not do without hydronic heating surfaces, as this is usually the consequence of offered exhaust air heat pumps.

Hydronic heating surface = underfloor heating? That is what is planned, at least.

So, an air-to-air heat pump would be better than an exhaust air heat pump? These are the units with a fan outside the house? For example, the Nibe F2120?

What would be an acceptable heating load? What exactly does this value refer to? For example, 7.5 kW per day, month, or year?

I don’t think I fully understand the difference yet.
Exhaust air heat pump (EHP) = The waste heat from the house heats the domestic hot water and the heating circuit.
So if I need hot water, I draw unnecessarily a lot of heat from my house, which I then have to reheat. Most likely using electricity.

Air-to-air heat pump = I use the outside air to warm up my water (domestic hot water and heating water) inside. It doesn’t really matter how much heat I need inside, since there is plenty of air available “outside.”

In both cases, though, it is a problem when it gets very cold outside, isn’t it?

An air-to-water heat pump, if done properly, is not a bad choice—in fact, quite the opposite, especially in your region. However, your offer does not sound like it is well executed.

The heating load for your house is no more than 4kW. The air-to-water heat pump should be modulating; then you can also choose, for example, a 6kW unit if nothing smaller is available. Otherwise, consider everything Domski has written.