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

Hi

Basically, the insulation effect does not increase linearly with the thickness of the insulation material; in my opinion, you could have saved that money.

**As far as summer heat protection is concerned: the purpose of insulation materials is to limit heat flow, not to store heat. A good solution for the roof area is a so-called rafter insulation, which, applied externally to the roof structure, completely envelops the entire construction. The roof is - cost-effectively, as less thickness is required - excellently protected from scorching heat in summer.

So my idea to do it this way came to me after I visited someone who had done it like I have now, when I still lived in my old house. Temperature in his attic was 21.8° and in mine 26.2° on the same day and time, and I think these are already clear arguments. In terms of location and equipment, quite similar. And you are right, it is not the task of insulation materials to store heat, but if I have the option to achieve both with one insulation material, why not. You can try entering the roof construction I have into the U-value calculator and then a conventional one, and you will see a clear difference in heat protection. And if you don’t trust the calculator, which is quite legitimate, then I can only refer back up 21.8° vs. 26.2° because that was how it was in practice.

Greetings from Lower Saxony

That depends on the roof structure in the old apartment. Otherwise, it’s - like in your calculations here from some randomly gathered stuff - comparing apples and oranges.

Just talk to the people involved with your house planning. They should know best where errors might be. Putting together dangerous half-knowledge yourself doesn’t help either.

Hello

That depends on the roof structure in the old apartment. Otherwise, it’s - like in your calculations here from some randomly gathered stuff - comparing apples and oranges.
.

The roof structure of the old house is as described above, only 18 cm of glass wool between the rafters, and from the other house as it is supposed to be for me, also described above.
And there I only wrote what I have measured myself with the thermometer. There is no randomly gathered stuff and no comparing apples and oranges.
And my question about achieving the KfW 70 standard was only whether it could be due to the forgotten values or not.
And regarding the people who do the calculations, I have already spoken to them and they say there is no error, so I just wanted to ask the general opinion on this matter in this forum, because with these values I simply could not imagine that KfW 70 would not be reached and then possibly go to someone else for calculation.
If the answer here had been that only with gas and with the wall, roof structure etc., it is highly unlikely to reach KfW 70, I would save myself a new calculation.

Regards

Hi,

a small addendum.
I only answered the question about the roof structure because the question came up as to why the roof structure is like that.
That was all concerning that. The rest revolves around achieving the KFW 70 standard.

Regards

Who calculates that for you? The structural engineer?

Some engineering office for structural analysis and energy consulting. Was commissioned by the home builder.