ᐅ Floor Construction for a New Single-Family House KfW55 Standard
Created on: 7 Apr 2016 08:17
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ElBoCaDiLlO
Hello everyone,
this is my first post in the forum. I hope you can help me a bit.
I have planned a prefabricated house, and with the recent changes in the energy saving regulations and since I will be installing an exhaust air heat pump, my insulation requirements have decreased.
To save some money, I wanted to skip the 16cm (6 inches) perimeter insulation under the concrete foundation.
Now, a new energy saving regulation calculation was done. The floor insulation consists of 20cm (8 inches) C20/25 concrete and 8.5cm (3.3 inches) WLG025 insulation under the screed. This results in a U-value of 0.27 W/m²K, which seems quite high for a KfW55 house, doesn’t it?
I’m not very familiar with this, which is also why I handed everything over, but all other values (roof, exterior walls) are around 0.14 W/m²K.
Do you see a simple way to improve the floor insulation, and above all, does it even make sense, or is this value sufficient?
The floors on both ground and upper levels will be fully equipped with underfloor heating.
I don’t have the exact floor structure on hand right now, but I can provide it if needed.
Many thanks and best regards from the sandwich.
this is my first post in the forum. I hope you can help me a bit.
I have planned a prefabricated house, and with the recent changes in the energy saving regulations and since I will be installing an exhaust air heat pump, my insulation requirements have decreased.
To save some money, I wanted to skip the 16cm (6 inches) perimeter insulation under the concrete foundation.
Now, a new energy saving regulation calculation was done. The floor insulation consists of 20cm (8 inches) C20/25 concrete and 8.5cm (3.3 inches) WLG025 insulation under the screed. This results in a U-value of 0.27 W/m²K, which seems quite high for a KfW55 house, doesn’t it?
I’m not very familiar with this, which is also why I handed everything over, but all other values (roof, exterior walls) are around 0.14 W/m²K.
Do you see a simple way to improve the floor insulation, and above all, does it even make sense, or is this value sufficient?
The floors on both ground and upper levels will be fully equipped with underfloor heating.
I don’t have the exact floor structure on hand right now, but I can provide it if needed.
Many thanks and best regards from the sandwich.
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nordanney7 Apr 2016 18:23If the expert advisor says it’s good, the laypeople here won’t tell you it’s bad.
Still, keep in mind that your insulation will be worse than before and, in my opinion, this will likely increase your already probably high heating costs. The energy issue is much more important! We have just an old KfW 70 house, but our energy consumption is significantly better than neighbors with a KfW 55 prefabricated house. It’s a matter of the overall system, not just one small component.
Still, keep in mind that your insulation will be worse than before and, in my opinion, this will likely increase your already probably high heating costs. The energy issue is much more important! We have just an old KfW 70 house, but our energy consumption is significantly better than neighbors with a KfW 55 prefabricated house. It’s a matter of the overall system, not just one small component.
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Sebastian799 Apr 2016 09:53I still believe your calculation is incorrect... mainly because you don’t heat continuously 24 hours a day, 365 days a year... that saves a few euros, but an underfloor insulation will probably never pay off...
We have the same construction, but with a basement, meaning 3m (10 feet) lower down
We have the same construction, but with a basement, meaning 3m (10 feet) lower down
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toxicmolotof9 Apr 2016 10:00Why do houses where the energy performance calculation according to KfW standards is done by the seller still seem so suspicious to me?
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Sebastian799 Apr 2016 12:02The assessment in the energy saving ordinance calculation is just a pointless numbers game.
ElBoCaDiLlO schrieb:
oh Wo Du Recht hast ABER ^^ 0.064 W/m²K * 0.2€ * 24h * 365d * 0.001 * 20K * 100m² = 224.56€ also nur das Komma verschoben Dann sieht das doch wieder anders aus, aber gibt ja immer noch keine Infos darüber, ob sich das dann auch wirklich so darstellt. What’s with the 0.20 EUR? You pay 20 cents for one kWh of thermal energy? More like 5–6 cents, right? Try 0.06 EUR and 180 heating days and you get about 30 EUR per year. This is just a rough estimate (and maybe the exhaust air heat pump even costs more than 6 cents – unlike an outdated gas boiler), but it’s probably closer to reality.
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