ᐅ kfw40plus monolithic solid construction – tips and experiences?
Created on: 8 Mar 2016 17:25
B
bellamucHello everyone,
we are planning to build a house in the Allgäu region. Since it will not be small and includes three residential units, we would like to take advantage of the kfw40plus subsidy. Photovoltaics are already planned extensively (covering the entire roof), so that is settled. Additionally, there will be a hydronic fireplace stove.
I definitely want to build with solid construction and prefer no external insulation. Ideally, I would like a purely monolithic wall made of materials like aerated concrete or expanded clay blocks (so without insulated blocks such as Cariso).
The house will be built on a hillside, with the basement partially exposed on one side and used as living space. Therefore, I would prefer a masonry basement if it is not counterproductive to achieving the kfw40+ standard.
I have received various opinions from construction companies and architects (including passive house planners). It seems everyone tries to sell me the solution they are familiar with.
How can I calculate whether, for example, a 42.5cm (17 inches) thick Ytong wall can meet the kfw40+ standard and which additional measures I need to take (windows, roof, basement floor, other energy-related measures...)?
Maybe there are other factors I can adjust so that the masonry can be as thin as possible (perhaps even 36.5cm (14 inches) plus plaster)? Of course, all this should not cost more than what the subsidy and heating cost savings justify.
Some say that the 0.07 W/(m·K) Ytong or Poroton blocks are so fragile they break easily in your hands… I should rather use 0.08 W/(m·K) blocks and make the wall thicker… there are so many opinions.
Is there anyone here who has really built purely monolithic solid and met the kfw40+ standard?
Any tips?
Greetings from Munich.
we are planning to build a house in the Allgäu region. Since it will not be small and includes three residential units, we would like to take advantage of the kfw40plus subsidy. Photovoltaics are already planned extensively (covering the entire roof), so that is settled. Additionally, there will be a hydronic fireplace stove.
I definitely want to build with solid construction and prefer no external insulation. Ideally, I would like a purely monolithic wall made of materials like aerated concrete or expanded clay blocks (so without insulated blocks such as Cariso).
The house will be built on a hillside, with the basement partially exposed on one side and used as living space. Therefore, I would prefer a masonry basement if it is not counterproductive to achieving the kfw40+ standard.
I have received various opinions from construction companies and architects (including passive house planners). It seems everyone tries to sell me the solution they are familiar with.
How can I calculate whether, for example, a 42.5cm (17 inches) thick Ytong wall can meet the kfw40+ standard and which additional measures I need to take (windows, roof, basement floor, other energy-related measures...)?
Maybe there are other factors I can adjust so that the masonry can be as thin as possible (perhaps even 36.5cm (14 inches) plus plaster)? Of course, all this should not cost more than what the subsidy and heating cost savings justify.
Some say that the 0.07 W/(m·K) Ytong or Poroton blocks are so fragile they break easily in your hands… I should rather use 0.08 W/(m·K) blocks and make the wall thicker… there are so many opinions.
Is there anyone here who has really built purely monolithic solid and met the kfw40+ standard?
Any tips?
Greetings from Munich.
I would assume that an independent energy consultant with proper training can help. Alternatively, an architect—though no one will do it for free, as it is a planning service after all. Another option is to follow informal advice or educate yourself.
Your specialist planner will likely review the technologies you have "chosen" again—considering their practicality and cost-effectiveness—for example, photovoltaic systems over 10 kWp; a residential unit with a stove going on vacation, and so on.
Your specialist planner will likely review the technologies you have "chosen" again—considering their practicality and cost-effectiveness—for example, photovoltaic systems over 10 kWp; a residential unit with a stove going on vacation, and so on.
The purpose of the photovoltaic system becomes clear when relocating an existing installation, operating electric vehicles, and having a public charging station. The surplus electricity is sufficient to heat all residential units.
The wood-burning stove is intended for ambiance and possibly as an adjustment to meet funding requirements. As a double backup for heating/domestic hot water, I am open to additional options, such as pellets, a heat pump, or simply a gas condensing boiler.
As I mentioned, I consulted several technical planners, energy advisors, and architects. Each one tries to discourage me from pursuing KfW40 Plus or persuade me to choose timber frame construction or external thermal insulation composite systems (ETICS). It seems no one likes to venture into uncharted territory... maybe there isn’t even an option? That may be true. But here in the forum, I read that builders have achieved KfW40 standard even with monolithic Liapor exterior walls of 42.5cm (17 inches). It must be possible somehow—KfW would hardly try to steer builders away from solid construction, especially since there are energy savings potential in the production of exterior walls, not to mention recycling!
Who can show me which wall constructions are possible monolithically? And which measures could possibly compensate for a weaker wall structure?
The wood-burning stove is intended for ambiance and possibly as an adjustment to meet funding requirements. As a double backup for heating/domestic hot water, I am open to additional options, such as pellets, a heat pump, or simply a gas condensing boiler.
As I mentioned, I consulted several technical planners, energy advisors, and architects. Each one tries to discourage me from pursuing KfW40 Plus or persuade me to choose timber frame construction or external thermal insulation composite systems (ETICS). It seems no one likes to venture into uncharted territory... maybe there isn’t even an option? That may be true. But here in the forum, I read that builders have achieved KfW40 standard even with monolithic Liapor exterior walls of 42.5cm (17 inches). It must be possible somehow—KfW would hardly try to steer builders away from solid construction, especially since there are energy savings potential in the production of exterior walls, not to mention recycling!
Who can show me which wall constructions are possible monolithically? And which measures could possibly compensate for a weaker wall structure?
B
Bauexperte11 Mar 2016 10:15Hello,
You will need an independent energy consultant to accompany the construction project. It would be wise to engage with them early on so that all components — basement plus two residential units — can be occupied without any loss of comfort at the end of the day. This also applies inversely to possible oversizing. At minimum, you need a sales representative who has experience with this type of building and understands the subject well.
I have a slight feeling that you are getting lost in planning without really knowing what will _exactly_ come at you. Do you already have a design and a price estimate?
Regards, Bauexperte
bellamuc schrieb:I understand the photovoltaic system, but I’m not familiar with this type of stove. You should definitely discuss this with a mechanical, electrical, and plumbing (MEP) engineer.
The photovoltaic system is already planned extensively (the entire roof), so that’s settled. Also, a water-circulated wood stove.
bellamuc schrieb:You can’t do that yourself; there are professionals who have studied this thoroughly and continuously update their knowledge.
How can I calculate whether a 42.5cm (17 inches) Ytong wall, for example, will meet the KfW 40+ standard and what additional measures I need to take (windows, roof, basement floor, other energy-saving measures...)?
bellamuc schrieb:KfW 40 and KfW 40+ are no problem at all for monolithic construction. However, you will very likely have to give up on achieving this with a 36.5cm stone. Since you initially mentioned 3 residential units, a little “loss” of floor area with a 42.5cm stone should not be an issue.
Maybe there are other ways to adjust some parameters so that the masonry can be as thin as possible (possibly even 36.5cm (14.5 inches) plus plaster)? Of course, the whole thing shouldn’t cost more than the subsidy and heating cost savings would cover!?
Some say the 0.07 W/(m·K) Ytong or Poroton is so delicate it breaks in your hands... I should rather go with 0.08 and make the wall thicker... there are so many opinions.
Is there anyone here who has actually built monolithic solid walls and achieved the KfW 40+ standard?
Any tips?
You will need an independent energy consultant to accompany the construction project. It would be wise to engage with them early on so that all components — basement plus two residential units — can be occupied without any loss of comfort at the end of the day. This also applies inversely to possible oversizing. At minimum, you need a sales representative who has experience with this type of building and understands the subject well.
I have a slight feeling that you are getting lost in planning without really knowing what will _exactly_ come at you. Do you already have a design and a price estimate?
Regards, Bauexperte
Hello Building Expert,
Thank you for the information. I have already answered some questions in my post submitted at the same time.
Certainly, there is a completed and approved building permit / planning permission. Financing is also secured. I am simply looking for a builder and/or architect to carry out the project.
Builders all provide me only with offers for KfW 55 standard. I would have to sign this offer and then enter the costing phase… only then would I know the extra cost to achieve KfW 40+. This is unsatisfactory. There are suggestions that this can only be done with extensive effort and 50cm (20 inches) thick walls, and that it will cost more than the repayment subsidies (3 × €15,000 + €18,000).
An energy consultant and passive house planner I found, who seems competent and open enough, on the other hand, sees the feasibility, but does not give me a price for the construction. They say this requires detailed planning, which would initially cost me about €4,000 (approx. $4,200). Only after that would I know the price at all and might then realize that this is outside the budget or that KfW 55 would actually be the more economical option!?
Thank you for the information. I have already answered some questions in my post submitted at the same time.
Certainly, there is a completed and approved building permit / planning permission. Financing is also secured. I am simply looking for a builder and/or architect to carry out the project.
Builders all provide me only with offers for KfW 55 standard. I would have to sign this offer and then enter the costing phase… only then would I know the extra cost to achieve KfW 40+. This is unsatisfactory. There are suggestions that this can only be done with extensive effort and 50cm (20 inches) thick walls, and that it will cost more than the repayment subsidies (3 × €15,000 + €18,000).
An energy consultant and passive house planner I found, who seems competent and open enough, on the other hand, sees the feasibility, but does not give me a price for the construction. They say this requires detailed planning, which would initially cost me about €4,000 (approx. $4,200). Only after that would I know the price at all and might then realize that this is outside the budget or that KfW 55 would actually be the more economical option!?
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