ᐅ Energy Efficiency Certificate KfW55 – Target KfW40 – Question: Steps & Costs
Created on: 19 Apr 2016 13:26
W
world-eHello everyone,
I have a question regarding structural engineering and energy efficiency:
We are currently planning a timber frame house with a basement. A ventilation system is also planned but has not been included in this energy performance calculation. According to the energy certificate, it is currently a KfW55 house. Please see the attached excerpts in the PDF. If more information is needed, please ask.
When I asked the energy consultant what would be necessary to achieve KfW40, he said the basement insulation would need to be 16cm instead of 12cm thick. This would result in the timber frame wall needing to be thicker as well (also for structural reasons). When I asked if the wood fiber insulation on the exterior wall could simply be made thicker (120mm instead of 60mm) to reach a U-value close to 0.11, he replied that this is not possible because the timber studs must rest about two-thirds on the foundation slab or basement ceiling. This would again require a thicker stud. Overall, the additional costs would be around €30,000–40,000, which would never pay off. I was not given any further explanation as to why the costs are this high.
My questions are:
1.) What do you think about these additional costs — can they be realistic?
2.) The wood fiber insulation boards don’t necessarily have to end flush with the outer edge of the concrete, right? They can protrude, correct? If the wood fiber board is thicker, it would just stick out a bit (6cm) without requiring any changes to the timber framing. And if the wood fiber insulation extends outward, wouldn’t the basement insulation be able to be thicker as well?
3.) What other options might I have to achieve KfW40 in a cost-effective way?
I hope you can help me understand this better. Many thanks.
I have a question regarding structural engineering and energy efficiency:
We are currently planning a timber frame house with a basement. A ventilation system is also planned but has not been included in this energy performance calculation. According to the energy certificate, it is currently a KfW55 house. Please see the attached excerpts in the PDF. If more information is needed, please ask.
When I asked the energy consultant what would be necessary to achieve KfW40, he said the basement insulation would need to be 16cm instead of 12cm thick. This would result in the timber frame wall needing to be thicker as well (also for structural reasons). When I asked if the wood fiber insulation on the exterior wall could simply be made thicker (120mm instead of 60mm) to reach a U-value close to 0.11, he replied that this is not possible because the timber studs must rest about two-thirds on the foundation slab or basement ceiling. This would again require a thicker stud. Overall, the additional costs would be around €30,000–40,000, which would never pay off. I was not given any further explanation as to why the costs are this high.
My questions are:
1.) What do you think about these additional costs — can they be realistic?
2.) The wood fiber insulation boards don’t necessarily have to end flush with the outer edge of the concrete, right? They can protrude, correct? If the wood fiber board is thicker, it would just stick out a bit (6cm) without requiring any changes to the timber framing. And if the wood fiber insulation extends outward, wouldn’t the basement insulation be able to be thicker as well?
3.) What other options might I have to achieve KfW40 in a cost-effective way?
I hope you can help me understand this better. Many thanks.
A classic example of how KfW funding is usually not primarily desirable, but rather a nice gimmick if the desired house also meets the KfW requirements.
Whether the high costs are justified in your case cannot be answered. If you were to start planning from scratch to build a KfW 40 house, it would probably be cheaper than trying to upgrade from KfW 55...
Whether the high costs are justified in your case cannot be answered. If you were to start planning from scratch to build a KfW 40 house, it would probably be cheaper than trying to upgrade from KfW 55...
jochi79 schrieb:
€3000 for additional insulation of the floor slab
€3200 for additional insulation of the houseI find this amount quite acceptable, as it can almost be fully recovered through the extra loan repayment subsidy. You save on heating costs, and the house gains added value.
Similar topics