ᐅ Aerated concrete exterior wall vs. energy efficiency regulations
Created on: 28 Jun 2015 20:07
T
tecker2010
Hi,
I hope this topic hasn’t been asked before; otherwise, I must admit I didn’t use the search function thoroughly enough.
We are planning to build a single-family house and are currently in the preparation phase. The plan is for a townhouse-style villa (2 full floors) with 150m2 (1,615 sq ft). Right now, I’m looking into exterior walls, energy-saving regulations, etc., and I’ve come across some fundamental questions—or rather, several.
According to our builder, standard exterior walls will be made of aerated concrete blocks (brand Ytong) with a thickness of 24cm (9.5 inches) without any additional insulation or external thermal insulation composite system (ETICS). Assuming the blocks used have a thermal conductivity of 0.09 W/(m·K) (there are different blocks ranging from 0.07 to 0.18), my rough calculations lead to a U-value of 0.37 W/(m²·K), or about 0.3 W/(m²·K) if we opt for 30cm (12 inches) thick walls. In terms of energy efficiency and future-oriented building, this is obviously insufficient.
I’ve read that according to the 2009 Energy Saving Ordinance (EnEV), exterior walls are allowed a maximum U-value of 0.28 W/(m²·K).
My specific questions are: Is this a regulation the builder is legally required to follow? What wall thickness would you recommend? Also, is what I’ve described correct?
I’m hearing different opinions, ranging from “Go for a 36cm (14 inches) wall thickness because of better insulation” (from someone who has built twice) to “I’d choose 24cm (9.5 inches) so the house can breathe and put enough solar panels on the roof for self-consumption” (an architect).
Thanks a lot for your feedback!
Sebastian
I hope this topic hasn’t been asked before; otherwise, I must admit I didn’t use the search function thoroughly enough.
We are planning to build a single-family house and are currently in the preparation phase. The plan is for a townhouse-style villa (2 full floors) with 150m2 (1,615 sq ft). Right now, I’m looking into exterior walls, energy-saving regulations, etc., and I’ve come across some fundamental questions—or rather, several.
According to our builder, standard exterior walls will be made of aerated concrete blocks (brand Ytong) with a thickness of 24cm (9.5 inches) without any additional insulation or external thermal insulation composite system (ETICS). Assuming the blocks used have a thermal conductivity of 0.09 W/(m·K) (there are different blocks ranging from 0.07 to 0.18), my rough calculations lead to a U-value of 0.37 W/(m²·K), or about 0.3 W/(m²·K) if we opt for 30cm (12 inches) thick walls. In terms of energy efficiency and future-oriented building, this is obviously insufficient.
I’ve read that according to the 2009 Energy Saving Ordinance (EnEV), exterior walls are allowed a maximum U-value of 0.28 W/(m²·K).
My specific questions are: Is this a regulation the builder is legally required to follow? What wall thickness would you recommend? Also, is what I’ve described correct?
I’m hearing different opinions, ranging from “Go for a 36cm (14 inches) wall thickness because of better insulation” (from someone who has built twice) to “I’d choose 24cm (9.5 inches) so the house can breathe and put enough solar panels on the roof for self-consumption” (an architect).
Thanks a lot for your feedback!
Sebastian