KFW70 house gas consumption is too high, what is the yield of the solar system?

Hello everyone,
we moved into our new build a year ago and can now evaluate for the first time how our energy costs stand, and we have the vague feeling that they are clearly too high. We have discussed this with our developer and are investigating the causes. However, I would also like to get your opinion. Here are some key data:

[*]KFW70
[*]180m² living space
[*]ETICS (External Thermal Insulation Composite System)
[*]Triple glazing
[*]Underfloor heating
[*]Hot water preparation AND heating support by solar (approx. 12m² on the roof) from COSMO
[*]750 liter tank
[*]3-person household (our little one is 4)

Our first annual statement showed that we supposedly consumed 28,500 kWh. Our research on the internet has shown that this is far too high for a KFW70 house. On average, you expect about 60 kWh/m² per year. Even if you double this value, our consumption would still be 8,000 kWh higher?? Also, we cannot understand to what extent our solar system is supposed to have contributed to the system since we have such high consumption values.

I would appreciate feedback; maybe we can exchange comparison values so we can assess where we stand on average with our value.

Hi!

I estimate your real consumption for 180 sqm and the house data at about 7,000-7,500 kWh.

The screed drying can also have accounted for 6-7,000 kWh.

So your real consumption within the key data framework is not directly explainable. Not even with the comparatively large hot water tank, which of course costs somewhat more energy (I roughly estimate that the energy required to maintain the heat there is about 4 kWh/day, so without producing hot water directly, about 1,500 kWh/year minus solar yields, which then cost no gas).

We also have KFW70, about 140 sqm, solar only for domestic hot water (300 l tank). Consumption about 6,400 kWh/year (we heat well, I like about 22 degrees inside). Solar support is low – last year very little, the year before a bit more (around 400-500 kWh). In short, the solar support can – as already said here – actually be more or less ignored, a nice gimmick.

Therefore, it is very likely that some kind of error in your system exists. Somewhere, about 8-10,000 kWh of energy is wasted senselessly. Starting from burner settings to other elemental points.
Your heating specialist company definitely needs to take a look.

Best regards
Thorsten

PS: Dumbest question of the day: Was the gas meter at 0.0 after installation?

Someone definitely needs to take another look. Often, it's small stupid mistakes that, if unnoticed, end up costing a lot of money. In our case, there was a wrong temperature sensor on the solar system (was NTC, should be PTC or vice versa). I noticed it relatively quickly because the pump was constantly running. Even at night. That way, the warm domestic water got nicely cooled (Für die Heizung macht die Solaranlage nichts). With a lighter on the sensor and a look at the temperature display in the controller, the matter was quickly clear. If you don't pay attention to this and it runs like that for months/years and maybe even a heating storage tank is connected...

Hello everyone, I wanted to briefly pick up the topic again and share that after 4 years we have now settled at around 16,000, which I find okay for the living space and now 4 people.