Energy Saving Ordinance 2016 / KFW55 / Gas + Solar in 2016

I'm not concerned about KfW 55 but whether it's even allowed to build without solar but with controlled residential ventilation with heat recovery.

Yes, you may, if the total of the calculation at least complies with the Energy Saving Ordinance 100 for your building.

You have to build according to the standard.

That corresponds - roughly, some values have been tightened, e.g. the transmission heat loss - to the "old" KFW70.

My KFW70 is also operated with a gas condensing boiler. Additionally thermal solar + controlled residential ventilation/heat recovery.
Not included: wood/fireplace. Photovoltaics. Came later.......

The house is about 40% better than the former KFW70 requirement, almost reaches KFW55, but never will..... (with the photovoltaics added later: yes..., but it's no use afterwards anyway).

Weak points are:
Ground slab insulation
Windows overall 1.1 (for an extra charge I could have taken 0.8).
Front door: pure horror, U 1.7, luckily it is small.....

The controlled residential ventilation with heat recovery already brings a lot!! If I understand the figures correctly (and I think I do), then the controlled residential ventilation brings noticeably more than the thermal solar system.

Whether it will be enough for you is only shown by the calculation of your individually planned building project.

Regards
Thorsten

Thank you for your detailed contribution.

I think it really needs to be calculated definitively, the architect (who is presumably a candidate) swears by deep drilling and is not in favor of 3 different systems (gas, solar & controlled residential ventilation)... But I can well imagine that for an architect, geothermal energy makes it much easier to comply with the energy saving ordinance and that is why it is often recommended.

1. Gladly done.

2. A colleague and friend of mine built in Thuringia, shortly after me. With deep drilling. New system, first from the manufacturer. COP 5.7. Just amazing, the house/the heating.

3. You have to a) pay for the deep drilling and b) be able to do it at all. b) was not fulfilled for me, so a) = no, it did not really come into play for me.

4. Controlled residential ventilation / heat recovery is in my opinion anyway sensible, we simply find it brilliant for the climate. That it also saves a bit: nice. Great. You would rather exclude that from the debate. You might be able to successfully operate a more diffusion-open building without controlled residential ventilation. But I wouldn’t be so sure about that. Diffusion-closed: greenhouse. You will turn into a tele-tubby inside the place. Another friend next door here omitted it..... Steffi and I always say: suffocate gradually. When you build today, I personally believe a controlled residential ventilation with heat recovery belongs in such a house. With enough money, also with humidification + cooling function.......

5. Thermal solar with a heat pump: pure nonsense. The heat pump, even an air-water heat pump with a COP (year) of 3.5 does more in summer.... So: if no heat pump but gas, then thermal solar. And please definitely use vacuum flat-tube collectors, spend the money, you will be glad. I regret that I have the normal ones, they only work in Tenerife weather......

Regards
Thorsten

I'm not concerned about KfW 55 but whether building is allowed at all, without solar but with controlled residential ventilation with heat recovery.

Yes, that's absolutely possible. One of the general contractors we are considering has exactly this as a standard. Since 2016, the building performance specification has replaced the ST with a decentralized ventilation system.

Thank you for the information. I am curious whether it will work for our house or our planning as well since, in my opinion, the additional costs for solar thermal will never (possibly >50 years) pay off.

In my opinion, the additional costs of solar thermal will never pay off (possibly >50 years).

The reality with normal collectors is even worse. You also have to consider the electricity costs for the circulation pump (approx. 40 W). And the financing costs.

Depending on how optimistically I calculate, I come to over 80 years.

The reason is: the system works well in sunshine. But only then. Unfortunately, that is very rare here. Short periods of sunshine are not enough, because the stratified storage tank is only heated at the bottom first, often nothing reaches the top. This slows down the cooling somewhat, but it is only a drop in the bucket.
In other words: with normal collectors, the usage/operating time is simply too short in these latitudes.

That’s why I also regret not having known this earlier, then I would have chosen the vacuum flat tube collector. That also works in the transitional season and does not require direct sunshine to get going.

Best regards
Thorsten