ᐅ Accurate Calculation by the Energy Consultant? Why Choose Solar for Heating?
Created on: 15 Jan 2016 19:26
K
Kerstin2
Hello everyone,
We have received our documents for the KfW loan and want to build a KfW-70 house.
Plan bricks T-18 (24 cm (9.5 inches) Poroton blocks) with 16 cm (6.3 inches) insulation. The foundation slab is insulated with 10 cm (3.9 inches) Styrodur insulation.
10% of the value is now supposed to come from solar support for heating! We didn’t want that at all. Solar should only be used for hot water, not for heating. We end up with a value just over 40, while the maximum allowed for the KfW-70 house is 69.xx. I don’t understand why we have to include solar for heating support when it only covers 10% of the heat demand.
What can we do?
We have received our documents for the KfW loan and want to build a KfW-70 house.
Plan bricks T-18 (24 cm (9.5 inches) Poroton blocks) with 16 cm (6.3 inches) insulation. The foundation slab is insulated with 10 cm (3.9 inches) Styrodur insulation.
10% of the value is now supposed to come from solar support for heating! We didn’t want that at all. Solar should only be used for hot water, not for heating. We end up with a value just over 40, while the maximum allowed for the KfW-70 house is 69.xx. I don’t understand why we have to include solar for heating support when it only covers 10% of the heat demand.
What can we do?
Saruss schrieb:
So, I need a small wind turbine as well. Still waiting for affordable cylindrical helical ones that were discussed ages ago.
Hello Saruss, in the model home park in Wuppertal, there is a house that has exactly that kind of wind turbine on the roof. I can’t recall the manufacturer right now. I plan to visit again sometime and talk to the people there about the device.
Best regards,
Thorsten
T21150 schrieb:
Hello Saruss, there is a house in the model home park in Wuppertal that has a wind turbine on the roof just like that. I can’t remember the manufacturer right now. I plan to visit again when I have the chance and talk to the people about the device.
Best regards, Thorsten Thanks, interesting. It’s been a while since I was there, and I hadn’t seen it yet.
The park was completely renovated the year before last.
Completely state-of-the-art technology. All houses interconnected, renewable energies and so much more. Very interesting place. I've always kept an eye on the wind turbine, but until now, I had other concerns.
I’m in a very windy location here, so something like that could be worthwhile. We’ll see.
Best regards,
Thorsten
Completely state-of-the-art technology. All houses interconnected, renewable energies and so much more. Very interesting place. I've always kept an eye on the wind turbine, but until now, I had other concerns.
I’m in a very windy location here, so something like that could be worthwhile. We’ll see.
Best regards,
Thorsten
B
Bieber081518 Jan 2016 07:37Kerstin2 schrieb:
What can we do?Give up on KfW70. Or search online for "KfW70 without solar thermal." Or provide more details ;-). Or choose a heat pump instead of a gas condensing boiler (?). Or ask the energy consultant who did the calculation if it’s possible to meet the KfW70 standard without solar thermal (and which measures would be needed).HTH
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Peanuts7418 Jan 2016 09:34T21150 schrieb:
Hi,
with gas heating, a portion of "renewable" energy is mandatory for a KFW70 standard.
Honestly: it doesn’t bring any real benefit. But it’s a regulation. Even if you meet and exceed the required values.
Domestic hot water solar thermal: never pays off. 30-40 cents income/day minus electricity costs for the circulation pump (5-10 cents/day), at best on 170-200 days/year. A complete joke.
With heating support: this only makes sense when using vacuum tube flat-plate collectors (about twice the price of regular collectors). Because in summer and most of autumn/spring you don’t need heating in a KFW70 house. I know this because I have one too (with Q_p and H_t closer to KFW55 standard). In winter (say October through mid-March), a conventional solar thermal collector no longer does anything except look good on the roof (and generate capital costs). Vacuum collectors perform significantly better here. And as is well-known: heating is needed mainly in winter, and that’s exactly where conventional solar thermal collectors do not work effectively. But in midsummer, you get 74°C (165°F) hot water for showering and a nice hot bath.
So just choose the most cost-effective solution. You will never recoup the investment for this nonsense here. It is nothing more than a nice but unnecessary gimmick imposed on gas-heated KFW70 houses for the sake of environmental awareness.
Best regards,
ThorstenIt sounds like you shower/bathe at 74°C (165°F)... That would be too hot for me ;-)
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