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

Hello everyone,
we moved into our new building 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 also discussed this with our builder and are researching the causes. However, I would also like to get your opinion. Here are some key data

[*]KFW70
[*]180m² living area
[*]ETICS
[*]Triple glazing
[*]Underfloor heating
[*]Hot water preparation AND heating support via 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 significantly too high for a KFW70 house. On average, one calculates with about 60 kWh/m² per year. Even if you double this value, our consumption would still be 8,000 kWh higher?? We also 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 reference values so that we can classify where we stand on average with our value.

Is there still building drying/screed drying involved here? Sometimes 6000 kWh also go into the environment. In the first year, one also tends to consume a bit more based on experience. It’s unclear whether your 750 l tank is being controlled unfavorably? 28,500 kWh heat loss is quite a figure. Do you have a controlled residential ventilation system with heat recovery? If not, you can probably expect a maximum of around 14,000 kWh (?) – always also depending on individual showering, bathing, and "I'm warm, I'll just leave the window open for continuous ventilation" behavior.

Hi,

28500 kWh??? Do you have a sauna club there or are you affiliated with a nudist association that sits naked in the house at 35 °C??

No, seriously, that’s more than just lazy. Are you sure there isn’t a reading error?

For comparison, our current house (first occupancy at the end of 2011) has
135 sqm plus basement
Gas heating with 5 sqm domestic hot water solar thermal system and regular radiators
14 cm insulation,
triple glazing,
probably didn’t quite reach the Kfw 70 standard.
No controlled residential ventilation, so no heat recovery either, but rather very generous ventilation where the bathroom window is sometimes forgotten to be closed and stays open for hours.

Two adults and since November 2014 one child.

The consumption last year was almost exactly 7500 kWh, in previous years between just under 8000 and 8500. Slightly more in the first year.

You now have more living space, so let’s add 50% to that and maybe you had a lot of drying from construction too, so add another 50%. That puts us somewhere around 15000 - 18000 kWh as a possible extreme value.
You really can’t have burned more than that in the house!

You urgently need to have the heating checked, is it sending the gas unburned out the chimney? I had that fun many years ago in a rental apartment. We were puzzled by the constant noise at the boiler, even when it was off. It was a bimetallic safety device that was broken and never shut off the gas supply. Fortunately, it went straight out the chimney, otherwise I wouldn’t be able to type these lines now....

Best regards,

Andreas

Exactly the same amount was consumed last year

in a 230 m2 house from 1936 with reasonably insulated roof, uninsulated facade, mostly double-glazed windows from 1996, solar system for hot water. Oh yes, we have thermostat-controlled wall radiators.
However, in the evening, the wood stove is often on for support on one floor.

Mhhhhhh, it's somehow really frightening.

Hi,

28500 kWh ??? Do you have a sauna club or are you part of a nudist association that sits naked in the house at 35 °C??

very cool! you saved my weekend

Wait another year... the screed drying really makes a big difference... I wouldn't expect too much from the solar system, especially regarding heating support... hardly anything comes of it...