Hello, we plan to start building our own home this year.
I already have two active discussion threads on this forum about it.
https://www.hausbau-forum.de/threads/Hausbau-kfw70-ca-150m-welche-Heizung-Gas-lwwp.12261/
https://www.hausbau-forum.de/threads/wir-wollen-bauen-ist-das-was-uns-angeboten-wird-so-i-o.12269/
We just got back from discussing the offer with the supplier.
I tried to talk about heating and ventilation; he shared his experiences, opinions, and advice.
This didn’t quite match what I had read so far, so now I’m uncertain and confused again.
We requested a 150m² (1,615 sq ft) solid house built to KFW 70 standard.
This is achieved through insulation and a gas-solar heating system. More details are in my other threads.
When I asked about a mechanical ventilation system with heat recovery, he said it’s not needed, that regular airing is sufficient.
He also said his son built a KFW 70 house with gas-solar three years ago and that he would never do that again. Better to build without KFW 70, save the money for the energy certificate inspection and the solar system (about 5,000), keep the insulation as is, and move on. Apparently, it’s not financially worthwhile.
Regarding the wall construction, another supplier told me the following:
Me: Is there an air gap between the insulation on the masonry and the facing brick?
He: Yes, of course, we don’t list that separately because it’s required by DIN (German industrial standards).
Today, with our current supplier:
Me: Is there an air gap between the insulation on the masonry and the facing brick?
He: No, that’s a cavity insulation. That might have been necessary in the past, but with today’s insulation materials, it’s no longer needed.
So what is correct? Is an air gap between the insulation and masonry required by DIN, or does it depend on which insulation material is used?
I already have two active discussion threads on this forum about it.
https://www.hausbau-forum.de/threads/Hausbau-kfw70-ca-150m-welche-Heizung-Gas-lwwp.12261/
https://www.hausbau-forum.de/threads/wir-wollen-bauen-ist-das-was-uns-angeboten-wird-so-i-o.12269/
We just got back from discussing the offer with the supplier.
I tried to talk about heating and ventilation; he shared his experiences, opinions, and advice.
This didn’t quite match what I had read so far, so now I’m uncertain and confused again.
We requested a 150m² (1,615 sq ft) solid house built to KFW 70 standard.
This is achieved through insulation and a gas-solar heating system. More details are in my other threads.
When I asked about a mechanical ventilation system with heat recovery, he said it’s not needed, that regular airing is sufficient.
He also said his son built a KFW 70 house with gas-solar three years ago and that he would never do that again. Better to build without KFW 70, save the money for the energy certificate inspection and the solar system (about 5,000), keep the insulation as is, and move on. Apparently, it’s not financially worthwhile.
Regarding the wall construction, another supplier told me the following:
Me: Is there an air gap between the insulation on the masonry and the facing brick?
He: Yes, of course, we don’t list that separately because it’s required by DIN (German industrial standards).
Today, with our current supplier:
Me: Is there an air gap between the insulation on the masonry and the facing brick?
He: No, that’s a cavity insulation. That might have been necessary in the past, but with today’s insulation materials, it’s no longer needed.
So what is correct? Is an air gap between the insulation and masonry required by DIN, or does it depend on which insulation material is used?
S
Sebastian7919 Apr 2015 10:31We just received the heating load calculation for our house – 8.1 kW.
And that despite our insulation not being excessive...
And that despite our insulation not being excessive...
Compared to the requirements before the energy saving regulation, your insulation is already quite excessive. No one denies that insulation also reaches a point of diminishing returns—but just look at houses from 1995... 130 kWh/m² was more or less normal back then—what do you have? 60? So twice as good, and even in 1995 everyone complained about having to insulate so heavily.
S
Sebastian7919 Apr 2015 10:43Is our insulation over the top? It’s just barely below the energy saving ordinance at the masonry.
The roof is a bit better...
Primary energy 38 and final energy 16...
The roof is a bit better...
Primary energy 38 and final energy 16...
The 2009 Energy Saving Ordinance... the Thermal Insulation Ordinance from 1995 (the predecessor of the Energy Saving Ordinance) specified a maximum U-value for walls of 0.5 W/m²K, while the 2009 Energy Saving Ordinance lowered it to 0.24 W/m²K – and as I said, I’m sure people were complaining back in 1995 as well.
BeHaElJa schrieb:
To be honest... what exactly can politicians do to reduce energy consumption? It basically comes down to better insulation or promoting environmentally friendly energy production...Energy can also be saved during the construction of buildings. If in the not-too-distant future we only build passive houses (which is where things are heading), there won’t be much more energy to save. With today’s insulation, assumed to be twice as good as in the 1990s, energy savings of 60, 70, or 80 kWh/m2 can be achieved. In 20 years, even with insulation twice as effective as today’s, you might only save an additional 10 or 15 kWh/m2. The era of “more insulation” is probably coming to an end...
That leaves the large area of embodied energy, which still has considerable potential for savings. In the future, buildings should be constructed using materials that require little energy to produce and are easy to recycle. Initial considerations in this direction already exist. For federal buildings, there is an effort to apply sustainable construction based on a holistic approach. Maybe politicians will eventually include this in programs like KFW and similar financing schemes?
In my opinion, this would be a step in the right direction: Who wants impressive “eco-friendly” passive houses that consume a lot of energy before construction and then end up as hazardous waste?
Back to the topic: In our case, KFW funding had an effect. We now have a solar system and have reduced our energy demand as a result, even though it isn’t financially profitable...
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