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
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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!
andi-2000 schrieb:
What I don’t understand, and please don’t take it the wrong way, as I am just starting out: every construction company, whether for solid or prefabricated houses, and every architect and planner I have spoken to, told me that KfW55 can only be achieved if the correct thermal conductivity of the materials is given AND the technology fits.
Regarding the technology, for gas this means a condensing boiler AND solar thermal plus controlled residential ventilation with heat recovery. I was given this information from different sources, so I have accepted it.
Has your energy consultant calculated such a good primary energy demand that KfW55 is actually possible without these three technology components?
Our appointment with the energy consultant is coming up soon, maybe I will know more thenWe had the same information and thought that we definitely had to include solar thermal. However, we also immediately said that we would prefer to avoid it.
The energy consultant told us from the beginning that it might be possible, but it would be quite tight.
Last Friday, he completed the approval documents (BZA) for the KfW application.
The calculated values are as follows:
Reference building: 67.9 kWh/(m2a) (kilowatt hours per square meter per year)
Our annual primary energy demand: 35 kWh/(m2a)
Hello XeNia,
we are planning to build soon as well, and your approach seems very interesting to me (gas + controlled residential ventilation with heat recovery without solar). You mentioned that with proper orientation you use more insulation on the roof and the base slab. Could you please provide more details (exact locations, thickness, and materials used, etc.)?
we are planning to build soon as well, and your approach seems very interesting to me (gas + controlled residential ventilation with heat recovery without solar). You mentioned that with proper orientation you use more insulation on the roof and the base slab. Could you please provide more details (exact locations, thickness, and materials used, etc.)?
Hi XeNiA,
since we are entering the final phase with our general contractor (GC) after purchasing the plot, I am also very interested in details about your planning. We haven’t had an appointment with the energy consultant yet, but our GC’s sales representative said, after consulting with the energy consultant, that compared to the usual gas plus solar combination, an additional solar panel would be necessary.
@andi-2000: Have you made any further progress on this topic?
since we are entering the final phase with our general contractor (GC) after purchasing the plot, I am also very interested in details about your planning. We haven’t had an appointment with the energy consultant yet, but our GC’s sales representative said, after consulting with the energy consultant, that compared to the usual gas plus solar combination, an additional solar panel would be necessary.
@andi-2000: Have you made any further progress on this topic?
NYC76 schrieb:
Hi XeNiA,
since we are entering the final phase with our general contractor after purchasing the plot, I am also very interested in the details of your planning. We haven’t had an appointment with the energy consultant yet, but the sales representative of our general contractor said, after consulting the energy consultant, that compared to the usual gas plus solar combination, an additional solar panel would be necessary.
@andi-2000: Have you made more progress on this topic?Hi,
Regarding the heating system, we are further along: it will be gas plus ventilation with heat recovery and solar thermal. Masonry 20+14.
The whole system is planned as KfW55.
Unfortunately, there were complications with the KfW financing. We were under time pressure and didn’t really have the chance to discuss with the energy consultant whether it could work without solar thermal. Maybe you can manage this better.
Best regards
It should be possible. My son-in-law used plastered aerated concrete Ytong 36.5; the house is a cubic 1.5-story building, air source heat pump by Junkers, controlled mechanical ventilation with heat recovery, no solar panels on the roof, and it meets KfW 55 standards, although just barely. But that’s enough to qualify for the 5000,-.
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