ᐅ Retrofitting a split air conditioning system in a KfW 55 energy-efficient house

Hello everyone,

we live in a condominium on one floor of a multi-family building that is 2 years old and built to KfW 55 standard.
For the warm summers, we would like to install a split air conditioning system in the bedroom for cooling only.

I have already read various opinions on whether this negatively affects the energy calculation and possibly the KfW funding.

Depending on the source, I have found the following versions:
a) Not at all, since it has nothing to do with the originally planned concept and is not relevant for heating the building, but rather just a comfort feature like a plug-in space heater.

b) Only with regard to the impact caused by the core drilling through the exterior wall.

c) Related to the operation with cooling/heating, although it is unclear to me which consumption values should be used here.

Can you help me with this? I couldn’t find clear information from KfW either.

Andii87 schrieb:

Can anyone help me here? I can’t find any clear information from the KfW either.

The KfW clearly states in its terms that any changes to the house that would invalidate the approved subsidy (for example, loss of airtightness, no longer meeting KfW 55 energy efficiency standards, etc.) within the first 10 years after receiving the funding will require you to repay the subsidy.

Whether and how an air conditioning system negatively affects your house should be determined by a planner and/or energy consultant.

And now my personal opinion: Just do it and don’t overthink it.

nordanney schrieb:

And now here is my personal answer: Just do it and don’t ask too many questions.

Definitely no core drilling!
The exterior wall is common property: you need to clarify in advance whether you are allowed to make a hole in the facade or to attach something there.
After all, this is not a single-family house where you can do whatever you want.

Andii87 schrieb:

Core drilling through the exterior wall

What does the homeowners' association say about the project?

ypg schrieb:

The exterior wall is common property: it needs to be clarified in advance whether you are allowed to make a hole in the facade or attach something there.

I assume this question has been resolved. Drilling is the lesser issue (20mm (0.8 inches)); the exterior appearance is usually the decisive factor.

Thanks for the responses. Of course, consent from the homeowners’ association regarding the appearance and so on has been obtained.
Just “doing it” is too risky for me, as this would also involve the other owners in terms of their subsidies.

Exactly, the KfW states that no modifications to the house need to be made or approved within 10 years.
But nowhere is it described in more detail whether or how split air conditioning units are considered in the calculation.
Of course, I can hire the planner to look into this and possibly recalculate. But it’s hard for me to believe that I’m the first person dealing with this issue.

Therefore, I’m interested in how it worked out for others who went through the planner, and what feedback they received.