ᐅ New construction KfW55 energy standard with gas heating, solar panels, and controlled ventilation system with heat recovery
Created on: 22 Oct 2016 14:03
X
XeNiA
Hello!
We are just starting the planning of our new build, and the big question we keep discussing is the heating system.
We are building a detached single-family house with 145 sq m (1560 sq ft) plus an expanded attic of about 40 sq m (430 sq ft) with underfloor heating (including in the attic).
We want to achieve KfW55 standard. The house will be built with solid masonry and brick veneer.
One thing we definitely want is a controlled ventilation system with heat recovery.
The most cost-effective option so far seems to be a combination of gas, solar thermal, and ventilation. The construction companies we are requesting quotes from are also offering a KfW55 package with improved insulation, as it might be difficult to meet the required standards otherwise.
An alternative (the second most affordable option) would be an air-to-air heat pump instead of gas.
What are the advantages and disadvantages of these two heating systems? What would the approximate expected monthly costs be?
Some heating installers have told us that achieving KfW55 with gas is not possible at all.
We are quite confused, and everyone says something different.
What are your experiences?
Thank you very much!
We are just starting the planning of our new build, and the big question we keep discussing is the heating system.
We are building a detached single-family house with 145 sq m (1560 sq ft) plus an expanded attic of about 40 sq m (430 sq ft) with underfloor heating (including in the attic).
We want to achieve KfW55 standard. The house will be built with solid masonry and brick veneer.
One thing we definitely want is a controlled ventilation system with heat recovery.
The most cost-effective option so far seems to be a combination of gas, solar thermal, and ventilation. The construction companies we are requesting quotes from are also offering a KfW55 package with improved insulation, as it might be difficult to meet the required standards otherwise.
An alternative (the second most affordable option) would be an air-to-air heat pump instead of gas.
What are the advantages and disadvantages of these two heating systems? What would the approximate expected monthly costs be?
Some heating installers have told us that achieving KfW55 with gas is not possible at all.
We are quite confused, and everyone says something different.
What are your experiences?
Thank you very much!
B
Bauexperte18 Nov 2016 23:22andi-2000 schrieb:
We will soon start building and aim to achieve KfW55; we prefer gas for heating. The general contractor told us that KfW55 is possible with gas (heat recovery ventilation + ventilation).But that "possible" sounds very stretched, doesn’t it?andi-2000 schrieb:
It might be that instead of the monolithic construction (36.5cm (14 inches) aerated concrete) we will need to use a 20cm (8 inches) block plus thermal insulation. We can live with that...Not just 24 + 16. The basement ceiling also needs additional insulation; if you continue with gas as the heat source, the amount of insulation in the attic floor will very likely have to be increased as well.andi-2000 schrieb:
Soon an energy consultant will review this and advise how to implement it.I hope you keep us updated Best regards, Bauexperte
L
lars-steina19 Nov 2016 13:49We are currently facing the same issue. We were offered an air-to-water heat pump, a decentralized ventilation system without heat recovery, and 36.5 cm (14 inches) aerated concrete. However, we would prefer to build with gas heating (air-to-water heat pump considered too inefficient, with an estimated annual performance factor of 3 according to the energy consultant, leading to higher monthly heating costs), solar thermal, and a central ventilation system including heat recovery (if the budget allows — referring to the ventilation system). The aim is not to build a KfW-certified house. Is the option with gas heating and no additional polystyrene insulation, which we want to avoid, feasible?
A third option (ground-source heat pump with collectors, controlled residential ventilation with heat recovery, 36.5 cm (14 inches) aerated concrete) is also under consideration. But I assume that the initial investment costs would be the highest for this option, right? What are the average costs to expect, and how does the annual performance factor look in this case?
Furthermore, I would like to know whether investing in a decentralized ventilation system without heat recovery is worthwhile at all.
Thank you for your opinions and assessments.
A third option (ground-source heat pump with collectors, controlled residential ventilation with heat recovery, 36.5 cm (14 inches) aerated concrete) is also under consideration. But I assume that the initial investment costs would be the highest for this option, right? What are the average costs to expect, and how does the annual performance factor look in this case?
Furthermore, I would like to know whether investing in a decentralized ventilation system without heat recovery is worthwhile at all.
Thank you for your opinions and assessments.
Hello!
A brief update from us:
The energy consultant has done the calculations, and we will now build using gas heating plus a controlled ventilation system with heat recovery. Additionally, extra insulation will be added to the floor slab and roof. This is still more affordable than the solar thermal system, which we had planned to include but will now forgo.
Our house is very compact, and the windows are well oriented. This made the calculations work out.
Best regards,
XeNiA
A brief update from us:
The energy consultant has done the calculations, and we will now build using gas heating plus a controlled ventilation system with heat recovery. Additionally, extra insulation will be added to the floor slab and roof. This is still more affordable than the solar thermal system, which we had planned to include but will now forgo.
Our house is very compact, and the windows are well oriented. This made the calculations work out.
Best regards,
XeNiA
XeNiA schrieb:
Hello!
A quick update from us:
The energy consultant did the calculations, and we will now build with gas plus controlled mechanical ventilation with heat recovery. Additionally, there will be extra insulation for the foundation slab and roof. This is still cheaper than the solar thermal system, which we wanted to avoid and now will.
Our house is very compact and the windows are well oriented, so this calculation worked out.
Best regards,
XeNiAHi XeNiA,
Is cost the only reason you want to do without the solar thermal system? We place a high value on solar thermal because it reduces gas costs during the non-heating season to a minimum, as the hot water for the shower and so on comes from the solar thermal system...
Regards
I currently live in a house built in the mid-1970s with a very modern gas condensing boiler. I record the consumption at least monthly. With four people, we use about 350 kWh of gas per month in summer—meaning no heating, only hot water. That corresponds to energy costs of around €21. For comparison, in November, during the heating period, we used about 3300 kWh, which is just under ten times as much.
Conclusion? Hot water is a negligible byproduct of gas heating.
How expensive is the solar thermal system again?
It will never pay off. Solar thermal is mainly done to meet the renewable energy requirement of the energy saving regulation (building permit/planning permission). As little as possible.
I think it’s great that XeNiA manages to achieve KfW 55 standard solely with controlled ventilation and heat recovery. The investment is probably higher than installing solar thermal, but at least it provides a real benefit in the form of improved comfort through air quality and mold prevention. Solar thermal is dead capital.
Conclusion? Hot water is a negligible byproduct of gas heating.
How expensive is the solar thermal system again?
It will never pay off. Solar thermal is mainly done to meet the renewable energy requirement of the energy saving regulation (building permit/planning permission). As little as possible.
I think it’s great that XeNiA manages to achieve KfW 55 standard solely with controlled ventilation and heat recovery. The investment is probably higher than installing solar thermal, but at least it provides a real benefit in the form of improved comfort through air quality and mold prevention. Solar thermal is dead capital.
Yes, we have done a lot of calculations back and forth, and in the end, this consistently turns out to be the most cost-effective option (in our case).
This topic has been the most discussed so far, and everyone recommends something different.
Whether our decision is the right one will probably only be clear in a few years after several heating seasons.
A mechanical ventilation system with heat recovery was important to us, and since that already costs around 12,000€ (about $13,000), we had to save money elsewhere.
Regards
This topic has been the most discussed so far, and everyone recommends something different.
Whether our decision is the right one will probably only be clear in a few years after several heating seasons.
A mechanical ventilation system with heat recovery was important to us, and since that already costs around 12,000€ (about $13,000), we had to save money elsewhere.
Regards
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