ᐅ Thermal Insulation, Energy Saving Regulations, KFW 70 / 55 / 40 – Your Experiences
Created on: 17 Feb 2015 17:09
H
Häuslebau3r
Hello everyone, as we would say here,
since I have now become quite engaged with this forum and am interested in more and more topics, the question of the right and “best” insulation has come up for me recently (still purely out of interest for now, but surely also practical at some point). I deliberately put the word best in quotation marks because there will always be different preferences and use cases.
I am fully aware that a standard house usually does not require insulation below U=0.14 W/(m²K). Therefore, I tried to look up the following values regarding the energy-saving regulations and the KfW houses 70 / 55 / 40.
I came up with the following values for the thermal transmittance coefficient:
Reference building according to Energy Saving Ordinance 2014
U-value | Roof 0.20 W/(m²K), Windows 1.30 W/(m²K), Exterior wall 0.28 W/(m²K), Basement wall 0.35 W/(m²K), Floor slab 0.35 W/(m²K)
KfW Efficiency House 70
U-value | Roof 0.17 W/(m²K), Windows 0.90 W/(m²K), Exterior wall 0.23 W/(m²K), Basement wall 0.25 W/(m²K), Floor slab 0.25 W/(m²K)
KfW Efficiency House 55
U-value | Roof 0.17 W/(m²K), Windows 0.90 W/(m²K), Exterior wall 0.18 W/(m²K), Basement wall 0.25 W/(m²K), Floor slab 0.25 W/(m²K)
KfW Efficiency House 40
U-value | Roof 0.15 W/(m²K), Windows 0.80 W/(m²K), Exterior wall 0.14 W/(m²K), Basement wall 0.20 W/(m²K), Floor slab 0.20 W/(m²K)
With the above values, it becomes clear what needs to be done regarding home insulation to meet certain standards. As mentioned above, other factors also play a role, such as roof, upper and ground floor windows, possibly the ceiling in the upper floor, exterior wall including roller shutter box, exterior door, exterior wall, and floor slab. But you have to start somewhere.
What I am curious about as a layperson is the comparison between the KfW 70 standard and the KfW 55 regarding the exterior wall. For me, this point represents basically the only difference related to the values mentioned above. Of course, you are also welcome to share your information and experience regarding windows, for example.
To achieve an exterior wall U-value of about 0.18 W/(m²K), there seem to be different options, as I have read in other threads, such as:
For me personally, only the monolithic wall construction is really an option. Of course, you have to consider that you end up with, for example, a 40cm (16 inches) thick wall to achieve certain values. Often, the windows are then described as “loophole-like” because there is so much material around them. How did you decide, or how would you evaluate this from your experience?
What types of blocks or bricks have you had good or bad experiences with? For example,
Now, go ahead and type away!
since I have now become quite engaged with this forum and am interested in more and more topics, the question of the right and “best” insulation has come up for me recently (still purely out of interest for now, but surely also practical at some point). I deliberately put the word best in quotation marks because there will always be different preferences and use cases.
I am fully aware that a standard house usually does not require insulation below U=0.14 W/(m²K). Therefore, I tried to look up the following values regarding the energy-saving regulations and the KfW houses 70 / 55 / 40.
I came up with the following values for the thermal transmittance coefficient:
Reference building according to Energy Saving Ordinance 2014
U-value | Roof 0.20 W/(m²K), Windows 1.30 W/(m²K), Exterior wall 0.28 W/(m²K), Basement wall 0.35 W/(m²K), Floor slab 0.35 W/(m²K)
KfW Efficiency House 70
U-value | Roof 0.17 W/(m²K), Windows 0.90 W/(m²K), Exterior wall 0.23 W/(m²K), Basement wall 0.25 W/(m²K), Floor slab 0.25 W/(m²K)
KfW Efficiency House 55
U-value | Roof 0.17 W/(m²K), Windows 0.90 W/(m²K), Exterior wall 0.18 W/(m²K), Basement wall 0.25 W/(m²K), Floor slab 0.25 W/(m²K)
KfW Efficiency House 40
U-value | Roof 0.15 W/(m²K), Windows 0.80 W/(m²K), Exterior wall 0.14 W/(m²K), Basement wall 0.20 W/(m²K), Floor slab 0.20 W/(m²K)
With the above values, it becomes clear what needs to be done regarding home insulation to meet certain standards. As mentioned above, other factors also play a role, such as roof, upper and ground floor windows, possibly the ceiling in the upper floor, exterior wall including roller shutter box, exterior door, exterior wall, and floor slab. But you have to start somewhere.
What I am curious about as a layperson is the comparison between the KfW 70 standard and the KfW 55 regarding the exterior wall. For me, this point represents basically the only difference related to the values mentioned above. Of course, you are also welcome to share your information and experience regarding windows, for example.
To achieve an exterior wall U-value of about 0.18 W/(m²K), there seem to be different options, as I have read in other threads, such as:
- Monolithic wall construction
- Functional exterior wall
- Double-shell exterior wall
For me personally, only the monolithic wall construction is really an option. Of course, you have to consider that you end up with, for example, a 40cm (16 inches) thick wall to achieve certain values. Often, the windows are then described as “loophole-like” because there is so much material around them. How did you decide, or how would you evaluate this from your experience?
What types of blocks or bricks have you had good or bad experiences with? For example,
- Aerated concrete plan block NeoStone U-value 0.17 W/(m²K)
- Aerated concrete plan block “SK08” U-value up to 0.18 W/(m²K)
- ThermoPlan MZ8 (mineral wool) – 42.5 cm (17 inches) 0.18 W/(m²K)
- Poroton T9 – 36.5 cm (14 inches) 0.23 W/(m²K) – therefore only suitable for KfW 70
- Poroton T8 – 42.5 cm (17 inches) 0.18 W/(m²K)
- Poroton T8 – 49 cm (19 inches) 0.15 W/(m²K)
- Poroton T7 – 42.5 cm (17 inches) 0.15 W/(m²K)
- UNIPOR W09 - Approval Z-17.1.-1042 | 0.20 W/(m²K) – therefore only suitable for KfW 70
- UNIPOR WS07 CORISO | Approval Z-17.1.-1074 0.18 W/(m²K)
- Ytong aerated concrete 0.07 – 36.5 cm (14 inches) 0.18 W/(m²K)
- Ytong aerated concrete 0.08 – 42.5 cm (17 inches) 0.18 W/(m²K)
- Ytong aerated concrete 0.09 – 48 cm (19 inches) 0.18 W/(m²K)
Now, go ahead and type away!
Häuslebau3r18 Feb 2015 17:01EveundGerd schrieb:
I would move back to Bavaria anytime! :rolleyes Bavarian houses are definitely much nicer than the northern brick-clad ones. D So, back to the wall and the possibly better (or worse) type of stone. But I gladly accept the compliment ^^ Some people also claim that the beer here is better, and especially the hearty food *laugh*
As I mentioned, my main concern is the different materials, but as was also noted—by Bauexperte, I believe—it seems that the preferred type of stone, if it ever comes to that point, is not offered or used by every construction company. I would just like to know some practical experiences, if there are any.
EveundGerd18 Feb 2015 22:47We built with aerated concrete blocks, following the energy-saving ordinance. However, since the electricians have only just started working in the house, I can’t say much yet about heating, heating costs, etc. It was important for us to build without external thermal insulation composite system (ETICS / external wall insulation). We also believe that Germany is currently going overboard with insulation. So far, we live in a house built in 1964, renovated but without a plastic outer layer.
We considered how long we could heat with gas given the additional costs/effort for KfW funding. If I take our heating load calculation and add a reasonable margin, we have a gas advance payment of €50–60 per month, including hot water. For a house size of 154 sqm (1,657 sq ft), I find that acceptable.
However, our underfloor heating system is already designed for a heat pump, so we might switch to that at some point. You never know what the future will bring.
By the way, we actually chose our general contractor based on the type of blocks he uses.
We considered how long we could heat with gas given the additional costs/effort for KfW funding. If I take our heating load calculation and add a reasonable margin, we have a gas advance payment of €50–60 per month, including hot water. For a house size of 154 sqm (1,657 sq ft), I find that acceptable.
However, our underfloor heating system is already designed for a heat pump, so we might switch to that at some point. You never know what the future will bring.
By the way, we actually chose our general contractor based on the type of blocks he uses.
B
Bauexperte19 Feb 2015 00:12Good evening,
Regards, Bauexperte
Häuslebau3r schrieb:That’s probably just wishful thinking. You Bavarians may laugh at a 0.25-liter (0.26 quart) glass, but you can’t really handle what’s inside, right?
Some even say that the beer here is better ...
Regards, Bauexperte
EveundGerd19 Feb 2015 00:53I won’t say anything about it now except: the contents of 0.25 liters (8.5 fl oz) is just a weak drink and not a proper beer at all. D
Häuslebau3r19 Feb 2015 07:17EveundGerd schrieb:
We built with Ytong, following the energy saving regulations. Since we just recently had the electricians in the house, I can't say much about heating or heating costs yet. It was important for us to build without external thermal insulation composite systems (ETICS). We also believe that Germany is currently overdoing insulation. Until now, we have lived in a house built in 1964, renovated but without a plastic outer layer.
We considered how long we could heat with gas given the additional costs and effort related to the KfW program.
If I take our heat load calculation and add a significant margin, our gas advance payment is about 50–60 € per month including hot water. For a house size of 154 sqm (1,657 sq ft), I find that acceptable.
However, our underfloor heating system is already designed for a heat pump, so we might switch to one at some point. You never know what the future brings.
By the way, we chose our general contractor based on the type of blocks he uses.Good morning
Well, that’s a perfect response to my question and attitude *laughs*
Just kidding, thank you very much for your contribution. May I ask which Ytong blocks you used? I assume you ended up with a wall U-value around 0.25–0.20 W/m²K? How thick were your blocks? For me, it’s exactly the same situation—I actually don’t want to build with ETICS, so the choice of block material is even more important than for others. The combination of gas heating with a heat pump for the underfloor heating sounds good, too. Ideally, you could add photovoltaic panels and be prepared for everything.
Did you notice any significant differences when selecting your general contractor based on the block type?
Häuslebau3r19 Feb 2015 07:22Bauexperte schrieb:
Good evening,
That is more wishful thinking. You Bavarians might laugh at 0.25, but you don’t really handle the content well, do you?
Regards, BauexperteEveundGerd schrieb:
I won’t say anything about that now except: 0.25 just tastes like weak beer and not proper beer DI know the region well since my mother is originally from there, or rather from the Ahr Valley, and we often visit relatives. You can manage a Kölsch now and then, but it’s like in an advertisement... it’s gone in one gulp. You really have to order a meter of it to get to a liter (about 1 quart). You’re better at processing the grapes than the hops there.
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