KFW 70 is not achieved, target values for gas condensing boilers

Hello,

There is no cobbled-together stuff there and also no comparing apples and oranges.

I am almost certain that the person you visited and where you took measurements would have achieved this effect as well, even if he had installed "only" a rafter overlay insulation.

In this respect, "emer's" comparison is not really valid

Rhenish greetings

Heating system Buderus GBH172 T75S 14KW with 750L buffer tank

Seems to me quite overdimensioned. Was there a miscalculation?

I know this doesn't help you now, but maybe it will help someone who reads this: I have contractually ensured that our house achieves the desired KFW level without any additional costs for us compared to the original planning basis. By the way, I really like your roof structure; because of our "open" roof truss and the summer heat protection, I have also dealt extensively with the U-value calculator.

We left out the KfW stuff because it is a political, lobby-driven mess that unnecessarily complicates the good idea of ecological building and steers it in the wrong direction. (Very condensed, subjective summary on my part) Initially, KfW rewards you with a slightly better 10-year loan, which isn’t that great with current interest rates anyway. However, all the planning and energy calculations are elaborate and complex. This complexity often leads to errors, and the range in which a house can be operated energy-efficiently with the chosen technology is rather narrow.

We are now building according to the 2009 Energy Saving Ordinance with 42.5 cm aerated concrete and gas condensing boilers. Underfloor heating. We can skip the solar stuff because the 15% rule applies.

..... and have also extensively dealt with summer heat protection using the U-value calculator.

Have you also read the liability and warranty disclaimers?
Anyone who believes that free tools on the internet actually contribute to saving should take a look at the liability disclaimers or terms and conditions!
Anyone who believes that economically usable knowledge is distributed for free probably lives in socialism.
The results of such "guides" are not legally binding, and therefore basically worthless!
These free guides and tools are financed through Google Adsense, not through technically or legally actually usable content.

Regards

Yes, sure. I should have hired a TGA planner and by chance you are one. I understand.

I think – with my modest mechanical engineering half-knowledge – I can at least interpret this page and its results to the extent that they give me a simple sense of the change in temperature profiles within the component considered when the parameters of the roof structure are also changed. Nothing more. It should be clear to the user that the author assumes no liability for these results. Anyone who does not understand this is probably too stupid to use the calculator correctly anyway.