KfW energy calculation with cooling heat pump

Hello everyone,

we are planning to install a Viessmann Vitocal 200 S heat pump. It is also capable of cooling to lower the room temperature via the underfloor heating accordingly. We are building a Kfw 40 house.

Do we need to consider anything regarding KfW/Bafa for using it? Does activating the cooling function have any negative effects on the energy calculation?

Thanks and best regards
Markus

No, everything is identical to a normal heat pump

According to our heating engineer, that doesn't make sense. Cooling should be done better through the controlled residential ventilation - but best through an air conditioning system.

According to our heating engineer, that makes no sense. Cooling should be done better via the controlled residential ventilation - but preferably via an air conditioning system.

You can hardly cool with controlled residential ventilation, as the volume flow is too low for that. Cooling with the underfloor heating system works to some extent. In the height of summer I do that quite often and you can already feel an effect. However, you can clearly notice that the floor is cooler. You should not overdo it either, because otherwise you get a condensation problem. And you don’t have dehumidification, which would also be useful in summer. There are plenty of topics on this in the forum. Of course, the best is a proper air conditioning system. That’s why I wouldn’t pay a high extra cost for cooling via underfloor heating and heat pump, unless it’s already included anyway.

Our heating engineer recommended cooling in summer via the controlled residential ventilation with a preceding cooling coil.

In addition, the supply air in summer (before it enters the house) should be directed through an underground pipe system on the property to use the lower temperature below the earth's surface in summer for additional cooling of the fresh air.

The pipe system should be installed by the civil engineer as part of the earthworks.

How something like this has to be implemented - no idea. I haven’t dealt with it yet. I think knows the system/principle.

The cooling function is, in my opinion, not taken into account in the calculation.

Regarding the underground pipe, you can find something under the term [Erdwärmetauscher], it is really just a thicker pipe (15-20cm diameter) that is laid underground and thus slightly cools the air when it is drawn in.
A pre-mounted cooling coil is initially a bit more difficult to understand what is meant; I suspect it refers to a brine [Erdwärmetauscher], where a brine circuit is laid underground and this cools the intake air by means of a radiator through which the air is blown.
The effect in both variants is not huge; usually, about 0.5-1.5°C is mentioned, but there is also dehumidification, which is not achieved by the heat pump through cooling via the underfloor heating.

However, both variants cannot be compared to a real air conditioning system due to the low heat transfer, which achieves much more cooling capacity with dehumidification and significantly higher airflows. With the air conditioning system, other issues regarding hygiene in the pipes due to the dew point and possibly falling condensate must also be considered.