KFW70 with gas-solar heating

Well, with a gas heating system, I would carefully calculate how much the solar thermal modules would cost me and how much gas I could save if I could leave the water heating to the sun almost completely in summer and partially in winter.

However, this can usually only be done individually for you by an energy or heating consultant, as many individual factors (orientation, roof slope, average hours of sunshine, etc.) must be taken into account in this calculation.

O.K. I also believe that we will need this "heating calculation" to make a good decision based on sufficient facts. So that means we will probably have to inform the provider that he is our choice. So far, I have wanted to hold back as long as possible so that "he" doesn't feel too sure, like he has us hooked, catching up will then be a child's play.

What does your financial advisor have to do with the KFW70 decision!? The financial advantage is a bit over 2,000 € - so not really financial. Additionally, there is the increased resale value (in Germany, everything supposedly needs a diploma). A KFW assessor doesn't really cost much for KFW70... especially since you want to build to that standard anyway. By the way, you can roughly calculate your heating load yourself if you know what standard you are building to.

We wanted to know if there is a difference for our financing whether we build KFW70 or not, and I even see disadvantages because of the 10-year fixed interest rate. Our financial advisor neither discouraged nor encouraged it. He also told us about this 2,000 difference, and based on what he told us, I decided that way. What I am building now still needs to be looked at in detail. What kind of boiler it is, whether I want it or not. But without KFW70 funding and an expert report, because I can order that again in 20 years if I want to sell the house then. In the village where we are building, it will never have a good price anyway.

But you get 0.85% on 50 T€ instead of ~1.5% and can even use the delta to pay down additionally (okay, that is somehow negligible). But okay - I can certainly understand your consideration with the fixed interest period - it would just be a shame if you don’t do it because of resentments towards the [KFW] system.

I first had to google "Ressentiments" ^^. Nah, it's not really a grudge but simply the personal view that it doesn't align with our financing plan. We have 2 building savings contracts, both half full; from both we only take the savings amounts because the conditions are bad. And in the end, we are at about 84% financing with a 20-year term, which simply gave me construction headaches about what to do with the 36K after 10 years. Is it possible, for example, that after 10 years I can have a KFW certified according to the status at the construction date, or do I have to meet the current KFW70 standard (2025)?