Hello everyone,
here is another topic I didn’t fully understand during the meetings with the builder and the energy consultant.
We are planning to use windows with triple glazing and a U-value of 0.7 W/m²K (0.12 Btu/h·ft²·°F).
For calculating the primary energy demand, the energy consultant averaged the U-value of the frame and the glass area for the windows.
He assumed a value of 1.1 W/m²K (0.19 Btu/h·ft²·°F) for the frame and 0.7 W/m²K (0.12 Btu/h·ft²·°F) for the whole window, which results in (1.1 + 0.7) / 2 = 0.9 W/m²K (0.16 Btu/h·ft²·°F).
He then used this value of 0.9 W/m²K (0.16 Btu/h·ft²·°F) as the U-value for our planned 46.19 m² (497 ft²) window area in his calculations.
Since we are quite close to the thresholds for KfW 40 and KfW 55 standards and the house currently meets KfW 55, we need to spend a bit more on better insulation, etc.
My question is whether a more detailed calculation for different components, for example for the windows, could also provide an advantage in terms of U-value.
If you take, for example, a small window where the ratio of frame to glass area is almost 1:1, and a window where the ratio is heavily weighted toward the glass area, my non-expert assessment leads to very different proportions for the overall U-value as well.
Another question I have is what options are available to improve the U-value of the frame itself. So far, our builder has not been able to provide any specific information about the actual U-value of the frame.
And finally, are there any online tools that allow you to estimate the energy demand yourself based on certain key parameters?
Thanks a lot for any tips & tricks 🙂
Ostsee
here is another topic I didn’t fully understand during the meetings with the builder and the energy consultant.
We are planning to use windows with triple glazing and a U-value of 0.7 W/m²K (0.12 Btu/h·ft²·°F).
For calculating the primary energy demand, the energy consultant averaged the U-value of the frame and the glass area for the windows.
He assumed a value of 1.1 W/m²K (0.19 Btu/h·ft²·°F) for the frame and 0.7 W/m²K (0.12 Btu/h·ft²·°F) for the whole window, which results in (1.1 + 0.7) / 2 = 0.9 W/m²K (0.16 Btu/h·ft²·°F).
He then used this value of 0.9 W/m²K (0.16 Btu/h·ft²·°F) as the U-value for our planned 46.19 m² (497 ft²) window area in his calculations.
Since we are quite close to the thresholds for KfW 40 and KfW 55 standards and the house currently meets KfW 55, we need to spend a bit more on better insulation, etc.
My question is whether a more detailed calculation for different components, for example for the windows, could also provide an advantage in terms of U-value.
If you take, for example, a small window where the ratio of frame to glass area is almost 1:1, and a window where the ratio is heavily weighted toward the glass area, my non-expert assessment leads to very different proportions for the overall U-value as well.
Another question I have is what options are available to improve the U-value of the frame itself. So far, our builder has not been able to provide any specific information about the actual U-value of the frame.
And finally, are there any online tools that allow you to estimate the energy demand yourself based on certain key parameters?
Thanks a lot for any tips & tricks 🙂
Ostsee
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