ᐅ KfW 55 standard with a timber house – U-values: wall 0.18 W/m²K – roof 0.16 W/m²K
Created on: 24 May 2015 10:20
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-Markus-
Hello,
While looking for a building partner, my wife and I found a local carpentry company that makes a very good impression on us and with whom we can well imagine collaborating.
What we like is the ecological construction method. In addition, the provider offers the installation level that I absolutely require, which other modular home manufacturers usually do not, or only include in the more expensive passive house walls.
The price also seems reasonable—especially since the above-mentioned ecological construction method reduces our land cost through a funding program.
My goal is to have a KfW 55 house—not (only) because of the funding, but also for permanently low operating costs. Again noted here: achieving the KfW 55 standard would make the land significantly cheaper.
The U-values upon inquiry are:
- Exterior wall: 0.187
- Roof: 0.166
In addition to geothermal energy, a controlled residential ventilation system is planned.
Are these U-values still considered standard today? I think the roof is quite good, but the exterior wall is only average compared to other providers.
Thanks and best regards
-Markus-
While looking for a building partner, my wife and I found a local carpentry company that makes a very good impression on us and with whom we can well imagine collaborating.
What we like is the ecological construction method. In addition, the provider offers the installation level that I absolutely require, which other modular home manufacturers usually do not, or only include in the more expensive passive house walls.
The price also seems reasonable—especially since the above-mentioned ecological construction method reduces our land cost through a funding program.
My goal is to have a KfW 55 house—not (only) because of the funding, but also for permanently low operating costs. Again noted here: achieving the KfW 55 standard would make the land significantly cheaper.
The U-values upon inquiry are:
- Exterior wall: 0.187
- Roof: 0.166
In addition to geothermal energy, a controlled residential ventilation system is planned.
Are these U-values still considered standard today? I think the roof is quite good, but the exterior wall is only average compared to other providers.
Thanks and best regards
-Markus-
Ok, that means with a brine-to-water heat pump and controlled residential ventilation with heat recovery, there should be fewer issues regarding the Q-factor.
For the heat transfer coefficient (HT), the building envelope plays a bigger role. I think using different windows (the ones calculated currently are just at the limit with a U-value of 1.3 W/m²K) could improve the results.
An HT of 0.306 (I misread earlier) is still acceptable without problems. However, according to my research, the 2016 energy-saving regulation requires 20% below 0.4, which equals 0.32. I’m not sure how good it is that new constructions are just barely meeting this limit...
Best regards,
-Markus-
For the heat transfer coefficient (HT), the building envelope plays a bigger role. I think using different windows (the ones calculated currently are just at the limit with a U-value of 1.3 W/m²K) could improve the results.
An HT of 0.306 (I misread earlier) is still acceptable without problems. However, according to my research, the 2016 energy-saving regulation requires 20% below 0.4, which equals 0.32. I’m not sure how good it is that new constructions are just barely meeting this limit...
Best regards,
-Markus-
I simply got all the insulation upgrades from my builder for the additional material cost – he said the labor would be the same anyway. So, everywhere it's WLG032 instead of 035, the basement insulation is 20mm (¾ inch) thicker all around, and the roof will be fully blown with wood fiber insulation.
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