ᐅ Alternative insulation with a thermal conductivity of 0.035 W/(m·K) instead of 0.032 W/(m·K)
Created on: 27 Sep 2017 06:31
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HRG83Hello everyone,
According to the Energy Saving Ordinance for KfW 70, the roof insulation is planned as follows...
Insulation between rafters 035, 200mm (8 inches) and insulation below rafters 035, 40mm (1.5 inches).
Would it be possible to omit the insulation below rafters and instead use a continuous insulation layer 032, 200mm (8 inches)? The U-value would change from 0.158 to 0.156.
According to the Energy Saving Ordinance for KfW 70, the roof insulation is planned as follows...
Insulation between rafters 035, 200mm (8 inches) and insulation below rafters 035, 40mm (1.5 inches).
Would it be possible to omit the insulation below rafters and instead use a continuous insulation layer 032, 200mm (8 inches)? The U-value would change from 0.158 to 0.156.
The Energy Saving Ordinance does not specify insulation thicknesses or construction methods. These can only be inferred from it at best.
By the way, KfW 70 no longer exists.
You should discuss changes to the roof structure with your architect and the insulation materials with your energy consultant (or whoever is responsible for the thermal insulation certificate). The same or better U-value is encouraging. But are you using WLG 032 (thermal conductivity 0.032 W/mK) mineral or glass wool for that? Or are you insulating the roof with EPS?!
By the way, KfW 70 no longer exists.
You should discuss changes to the roof structure with your architect and the insulation materials with your energy consultant (or whoever is responsible for the thermal insulation certificate). The same or better U-value is encouraging. But are you using WLG 032 (thermal conductivity 0.032 W/mK) mineral or glass wool for that? Or are you insulating the roof with EPS?!
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nightdancer27 Sep 2017 09:21HRG83 schrieb:
Hello everyone,
according to the Energy Saving Ordinance for KfW 70, the roof insulation is specified as...
cavity insulation between rafters with a thermal conductivity of 0.035 W/mK and a thickness of 200mm (8 inches), and insulation under rafters with 0.035 W/mK and 40mm (1.5 inches) thickness.
Would it be possible to omit the insulation under rafters and instead use a dense insulation board with 0.032 W/mK and 200mm (8 inches) thickness as cavity insulation? The U-value would change from 0.158 to 0.156.That is possible; the only question is which option is more cost-effective in the end.
Hello Alex85,
the 032 200mm (8 inches) compressed mineral wool insulation would even be almost 200€ cheaper. It is already available from several brands such as Urs***, Isov***, and others. I have a contact in the building materials trade. I just spoke directly with the person responsible for the energy-saving regulations, and it seems to work. I could have thought of that earlier too :-)
the 032 200mm (8 inches) compressed mineral wool insulation would even be almost 200€ cheaper. It is already available from several brands such as Urs***, Isov***, and others. I have a contact in the building materials trade. I just spoke directly with the person responsible for the energy-saving regulations, and it seems to work. I could have thought of that earlier too :-)
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