ᐅ KfW 40 or better in solid construction without additional insulation possible?
Created on: 18 Nov 2019 08:44
S
Specki
Hello,
I was initially set on a timber frame construction for my future house. However, I am now reconsidering solid construction because it does have its advantages. Ideally, I would prefer this without additional external insulation, as that would be redundant and insulation typically does not last as long as the masonry itself. Poroton seems the most appealing option to me at first glance.
But is that even feasible? Are there bricks (or other solid building blocks) that on their own meet the KfW 40 standard, or possibly perform even better?
Does anyone have experience with this? Has anyone actually built something like this?
I’m open to discussion if you believe additional insulation makes sense. However, no “Styrofoam” will be used on the exterior walls; if anything, it will be an alternative material.
The comments I would rather avoid are those suggesting a lower energy standard would be sufficient. I will not build anything below KfW 40.
Thanks in advance for your input.
Best regards,
Specki
I was initially set on a timber frame construction for my future house. However, I am now reconsidering solid construction because it does have its advantages. Ideally, I would prefer this without additional external insulation, as that would be redundant and insulation typically does not last as long as the masonry itself. Poroton seems the most appealing option to me at first glance.
But is that even feasible? Are there bricks (or other solid building blocks) that on their own meet the KfW 40 standard, or possibly perform even better?
Does anyone have experience with this? Has anyone actually built something like this?
I’m open to discussion if you believe additional insulation makes sense. However, no “Styrofoam” will be used on the exterior walls; if anything, it will be an alternative material.
The comments I would rather avoid are those suggesting a lower energy standard would be sufficient. I will not build anything below KfW 40.
Thanks in advance for your input.
Best regards,
Specki
Scout schrieb:
Biomass heating system or ground-source heat pump instead of air-source heat pump, possibly with battery storage.
A domestic hot water circulation system is then also not allowed...An air-to-water heat pump or air-source heat pump is sufficient for a Passive House or KfW 40 standard.
A biomass heating system or ground-source heat pump is not necessary for KfW 40 or Passive House.
A domestic hot water circulation system is possible if you want one.
haydee schrieb:
Domestic hot water circulation system is possible – if you want one This would already have been detrimental to funding under the KWf55 standard according to our general contractor, back in 2017.
And it’s always about the annual primary energy demand relative to the reference building: once the nominal demand is set, you can calculate / optimize a lower annual primary energy demand thanks to the higher annual performance factor of brine-to-water heat pumps compared to air-to-water. And just like that, only due to the better annual performance factor, you turn a KWf55 building into a KWf40 one, purely through more efficient technology. Not because the house “naturally” has a lower heating load.
@guckuck2
Yes, the building inspector will still be involved. And I’m not sure how things will work out regarding self-contracted work, since I want to do as much as possible myself. But that’s all thinking too far ahead. And you’re absolutely right. The topic is quite complex.
@haydee
From what I understand so far, a solid wood house is considerably more expensive.
@Scout:
Drinking water circulation is not an option at all. In my opinion, it makes no sense for a single-family home. I didn’t install it during the renovation of our two-family house either. Waiting 5-10 seconds is reasonable.
Is an air-source heat pump really not allowed for KFW40?
Anyway, I’m leaning towards a ground-source heat pump. But that’s a topic for much later, and I haven’t studied yet which one makes more sense.
Yes, the building inspector will still be involved. And I’m not sure how things will work out regarding self-contracted work, since I want to do as much as possible myself. But that’s all thinking too far ahead. And you’re absolutely right. The topic is quite complex.
@haydee
From what I understand so far, a solid wood house is considerably more expensive.
@Scout:
Drinking water circulation is not an option at all. In my opinion, it makes no sense for a single-family home. I didn’t install it during the renovation of our two-family house either. Waiting 5-10 seconds is reasonable.
Is an air-source heat pump really not allowed for KFW40?
Anyway, I’m leaning towards a ground-source heat pump. But that’s a topic for much later, and I haven’t studied yet which one makes more sense.
Information Sheet KfW "Appendix to the Information Sheet on Energy-Efficient Construction"
The requirements for a KfW Efficiency House 55 are met if the following specified structural and technical system criteria (reference values) are implemented. In this case, a calculated proof for the KfW Efficiency House 55 is not required. ,,,
For the technical systems, one of the six following system concepts must be implemented. The location of the heat generator or the heat transfer station must be inside the thermal building envelope, and a central domestic hot water system must be provided. A domestic hot water circulation system is permitted.
Condensing boiler, solar domestic hot water system (standard values according to DIN V 4701-10), central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
District heating with certified primary energy factor fp ≤ 0.7, central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
Central biomass heating system based on wood pellets, wood chips, or firewood, central exhaust air system
Brine-water heat pump with underfloor heating system for heat transfer, central exhaust air system
Water-water heat pump with underfloor heating system for heat transfer, central exhaust air system
Air-water heat pump with underfloor heating system for heat transfer, central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
The requirements for a KfW Efficiency House 55 are met if the following specified structural and technical system criteria (reference values) are implemented. In this case, a calculated proof for the KfW Efficiency House 55 is not required. ,,,
For the technical systems, one of the six following system concepts must be implemented. The location of the heat generator or the heat transfer station must be inside the thermal building envelope, and a central domestic hot water system must be provided. A domestic hot water circulation system is permitted.
Condensing boiler, solar domestic hot water system (standard values according to DIN V 4701-10), central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
District heating with certified primary energy factor fp ≤ 0.7, central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
Central biomass heating system based on wood pellets, wood chips, or firewood, central exhaust air system
Brine-water heat pump with underfloor heating system for heat transfer, central exhaust air system
Water-water heat pump with underfloor heating system for heat transfer, central exhaust air system
Air-water heat pump with underfloor heating system for heat transfer, central ventilation system with heat recovery (heat recovery rate ≥ 80 %)
We had one in the calculation, and it was not harmful. 2017
KfW 40. Passive houses are not better subsidized. However, we did not install any.
With the right building envelope, you don’t need any technology to achieve KfW 40 or a passive house. KfW 40+ is only possible with technology, which is also subsidized separately.
KfW 40. Passive houses are not better subsidized. However, we did not install any.
With the right building envelope, you don’t need any technology to achieve KfW 40 or a passive house. KfW 40+ is only possible with technology, which is also subsidized separately.
Okay.
But that’s not really the main issue here. My primary focus right now is on achieving effective insulation for the building envelope and exploring the best methods or variations to accomplish this.
Whether I officially classify it as Passive House, KFW40, or KFW50 can be decided later once all the criteria are considered.
What is certain is that there will be either a heat pump or a log wood boiler, with a strong preference for the heat pump.
There will be a mechanical ventilation system with heat recovery.
Most likely, photovoltaic panels will be installed on the roof.
These decisions are already quite fixed.
Right now, the real question is: solid construction (e.g., concrete or masonry) or timber frame.
But with the very high insulation levels desired, timber frame construction seems to have a cost advantage.
Now I need to determine if the lower cost compensates for any potential disadvantages.
Thanks so far for the active participation!
At least now I know that pure solid construction without additional insulation probably won’t meet my insulation expectations.
Best regards,
Specki
But that’s not really the main issue here. My primary focus right now is on achieving effective insulation for the building envelope and exploring the best methods or variations to accomplish this.
Whether I officially classify it as Passive House, KFW40, or KFW50 can be decided later once all the criteria are considered.
What is certain is that there will be either a heat pump or a log wood boiler, with a strong preference for the heat pump.
There will be a mechanical ventilation system with heat recovery.
Most likely, photovoltaic panels will be installed on the roof.
These decisions are already quite fixed.
Right now, the real question is: solid construction (e.g., concrete or masonry) or timber frame.
But with the very high insulation levels desired, timber frame construction seems to have a cost advantage.
Now I need to determine if the lower cost compensates for any potential disadvantages.
Thanks so far for the active participation!
At least now I know that pure solid construction without additional insulation probably won’t meet my insulation expectations.
Best regards,
Specki
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