ᐅ Renovating an Older Building According to KfW Standards

Hello everyone,

I’m quite torn. We have bought a house from the 1950s and want to make several changes before moving in, such as installing underfloor heating only on the ground floor, because the upper floor has wooden beam floors; otherwise, we would have liked to install it upstairs as well.

We will also get a new heating system. Since there is already a gas heating system, we have decided to go for a new gas heating system combined with solar panels.

While we’re at it, we also want to replace the windows. The ones currently installed still look fine, but they are almost 30 years old. Since we want to improve energy efficiency, we would like to renew the windows. Here, the question arises whether to choose double or triple glazing. As we would like to take advantage of available subsidies, we would have to opt for the triple-glazed option. However, some say that for older buildings, double glazing might be better due to the risk of mold.

I keep hearing from many people that the KfW program doesn’t necessarily make sense. I have consulted an energy advisor, and according to his plan, I should do the following:

– Insulate the basement ceiling from below
– Install underfloor heating in all heated rooms
– Replace windows and front door
– Insulate the attic and the flat roof
– Apply an external thermal insulation composite system
– Install an air-to-water heat pump
– Set up a controlled ventilation system with heat recovery

All of this sounds good, of course, but it will also cost a lot of money, and I wonder whether renovating the house up to KfW standards will really pay off in the end.

I would really appreciate some neutral opinions here. Thanks in advance.

Peter

Almost two weeks without a response, and your other thread is also rather sparsely populated. It takes quite a bit of effort for readers to imagine your project based solely on text descriptions. I see a causal link to the weak feedback.

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Hello,

I want to revisit this topic. Which KfW standard are you aiming to achieve with these measures? For our 1973 house, we could reach KfW 100 with the following measures (your list, adjusted):

• Basement ceiling insulation from below => for various reasons, we applied it from above, which is somewhat less energy efficient.
• Underfloor heating in all heated rooms => for height reasons, we only have it on the ground floor.
• Replacement of windows and front door
• Insulation of the attic and flat roof
• External thermal insulation composite system
• Air-to-water heat pump => if we used gas instead, we would reach KfW 115.
• Controlled residential ventilation with heat recovery => we are considering this; however, KfW 100 can be reached without it.
• + Photovoltaic system => not on your list, but in my opinion, definitely sensible with a heat pump.

I assume your energy consultant calculated this for a higher KfW class. In my view, there is a significant increase in subsidies when moving from individual KfW measures to the KfW Efficiency House standard. The differences between efficiency classes after that are less substantial.

Best regards

lukas81