ᐅ GAS / SOLAR or GAS / Ventilation with Heat Recovery

DerBjoern schrieb:
Strange, it should actually be possible. We achieved KFW70 with gas heating and controlled residential ventilation plus heat recovery. We decided against solar panels, but had to improve the insulation instead.

That’s also possible with additional insulation. I would estimate about 20cm (8 inches) extra thickness. But in the attic, we also wanted to be able to stand up.

ypg schrieb:
It’s also possible with additional insulation. I guess about 20cm (8 inches) thicker.

Well, unless you insulate with metal or glass, it’s usually just a few centimeters (inches) more.

ypg schrieb:
But we also wanted to be able to stand up in the attic

Is the space really that tight for you?!? And why?

DerBjoern schrieb:


Is it really that tight for you?!? And why?

Knee wall height of 130cm (structural dimension) (51 inches), roof pitch of 26 degrees... but it doesn’t matter now, we can manage with solar (for us, only gas was an option!).

ypg schrieb:
It is possible with additional insulation. I estimate about 20cm (8 inches) thicker. But we also wanted to be able to stand up in the attic.

Hello ypg,

I increased the roof insulation by 4cm (1.5 inches) — from 20 to 24cm (8 to 9.5 inches).
The walls stayed the same, only the roof changed.
Replacing the solar thermal system with 4cm (1.5 inches) more insulation is something I would definitely do again.
So: it’s worth checking and calculating!

Best regards,
Micha

DerBjoern schrieb:
Strange, it should actually be possible. We achieve KFW70 standard using gas heating combined with a controlled ventilation system plus heat recovery. We decided against solar panels, but in return we had to improve the insulation.

@Brian73
Regarding the ventilation: we were also offered the Lunos units. They are certainly not bad, but you should consider whether a centralized controlled ventilation system might be better. You should be able to find plenty of discussions about the pros and cons...

This is exactly how I would like to build and heat as well: a gas condensing boiler without solar, but with a controlled ventilation system featuring heat recovery. What level of insulation do I roughly need to achieve to compensate for this? We plan to build a timber frame house, which typically has a U-value for the external walls of 0.13 W/(m²·K) (approximately 0.74 Btu/(ft²·hr·°F)). The glazing will, of course, be triple with a U-value under 0.9 W/(m²·K) (approximately 5.0 Btu/(ft²·hr·°F)). The building footprint is square and located on a south-facing slope. Does anyone have experience or estimates on whether this concept (of course it needs to be calculated) has a chance of working? P.S.: Does the Enter key or line break not work for you as well?

So, our wall insulation is worse. I think it was 0.15. The roof has 24cm (9.5 inches) of insulation between the rafters and 4cm (1.5 inches) below the rafters. Unfortunately, I don’t remember how much insulation was under the floor slab at the moment. The windows are triple glazed with 0.6 glass and overall white frames—I’m not sure exactly. They had 90mm (3.5 inches) profiles with 6 chambers. I also can’t say how the ventilation system was included, but it’s a Wolf CWL 300. I don’t know if the Wolf brand is affordable. It’s a single-family house with a kind of front gable built in solid construction.