Hello everyone,
I just registered here because I have a topic that is very important to me. If this topic is in the wrong forum, I kindly ask the moderator to move it if necessary.
We are planning to build this year and are currently (hopefully) at the end of the planning phase. The house will be built according to the 2012 energy saving ordinance.
We are planning a house with around 170-190 sqm (1,830-2,045 sq ft) of living space, which will have a basement built partially above ground into a hillside. Besides two smaller rooms and a utility room, the basement includes a double garage. The house will be heated with geothermal energy in the future.
Right now, we are refining the budget, which has gotten somewhat out of control (10% deviation from the target). We have already made some contributions ourselves, cut items, and reduced the size.
Our builder recently suggested reconsidering the planned KfW 70 standard because the additional investments would only pay off in the very long term (30 to 50 years).
Some background: Whether we keep or abandon the KfW 70 standard, the house will definitely have a geothermal heating system, as well as the planned bricks (thickness and lambda value) required for the KfW standard.
The following (cut) items are under discussion:
- The roof insulation will be done with 180 mm (7 inches) instead of 220 mm (9 inches) thickness (same lambda value 0.35) – 220 mm is actually necessary given the size of the house
- The cladding of the reinforced concrete parts will be reduced by about 2 cm (0.8 inches) of polystyrene
- A different insulation for the floor slab will be used (the new insulation has a worse lambda value)
These changes would reduce construction costs by 8,000 Euros but would mean losing the KfW 70 standard.
Still, I hesitate to give up the KfW 70 standard for the following reasons:
My questions to you are:
Thank you very much for your feedback.
f-pNo
I just registered here because I have a topic that is very important to me. If this topic is in the wrong forum, I kindly ask the moderator to move it if necessary.
We are planning to build this year and are currently (hopefully) at the end of the planning phase. The house will be built according to the 2012 energy saving ordinance.
We are planning a house with around 170-190 sqm (1,830-2,045 sq ft) of living space, which will have a basement built partially above ground into a hillside. Besides two smaller rooms and a utility room, the basement includes a double garage. The house will be heated with geothermal energy in the future.
Right now, we are refining the budget, which has gotten somewhat out of control (10% deviation from the target). We have already made some contributions ourselves, cut items, and reduced the size.
Our builder recently suggested reconsidering the planned KfW 70 standard because the additional investments would only pay off in the very long term (30 to 50 years).
Some background: Whether we keep or abandon the KfW 70 standard, the house will definitely have a geothermal heating system, as well as the planned bricks (thickness and lambda value) required for the KfW standard.
The following (cut) items are under discussion:
- The roof insulation will be done with 180 mm (7 inches) instead of 220 mm (9 inches) thickness (same lambda value 0.35) – 220 mm is actually necessary given the size of the house
- The cladding of the reinforced concrete parts will be reduced by about 2 cm (0.8 inches) of polystyrene
- A different insulation for the floor slab will be used (the new insulation has a worse lambda value)
These changes would reduce construction costs by 8,000 Euros but would mean losing the KfW 70 standard.
Still, I hesitate to give up the KfW 70 standard for the following reasons:
- I cannot estimate how much energy can actually be saved by keeping the measures under discussion (is the claim of paying off within up to 50 years accurate?)
- The KfW financing is about 1% cheaper than a normal loan with a 10-year fixed interest rate – meaning for 50,000 Euros, you save around 4,500 Euros in interest over 10 years
- Giving up the KfW 70 standard might reduce the potential resale value
My questions to you are:
- What do you think about this?
- If I decide to go with KfW 70: Are the stated 50 years (or possibly 30 years) for the measures to pay off realistic?
Thank you very much for your feedback.
f-pNo
Hello everyone,
thanks for the information.
At the beginning, I need to point out again that I am a layperson. Therefore, I am not sure if I have correctly assigned the abbreviations used.
Ht = heating technology
qp = according to Google, this could mean quality inspection
Of course, I am aware that the KfW requirements are based on a combination of heating technology and insulation, windows, doors, etc. However, I do not know how each factor individually influences the outcome (other than the simplified understanding that if you reduce one element, you have to increase another to achieve a similar standard).
@Jaydee
We had researched this topic a lot beforehand and often read that although air-to-water heat pumps are officially designed for temperatures down to -15°C (5°F), they often struggle below -10°C (14°F). Therefore, although they are cheaper, we decided against these systems.
So far, there actually is no heat demand calculation. However, his suggestion of geothermal heating (he mostly builds with geothermal systems) was very appealing to us since we were thinking along the same lines. He also gave us a rough figure (I don’t currently have the documents at hand, so I’m writing from memory) — he assumes an energy demand of 50 watts per square meter. That means we need a pump with 8.5 kW capacity (if I calculated correctly).
Regardless, his remark about “giving up the KfW70 standard” is initially just a suggestion or food for thought. The problem is that I can’t really understand how maintaining insulation for KfW70 or dropping that standard would affect consumption. Consequently, I can’t fully grasp the sense or nonsense of this measure. I have scheduled an appointment with an energy consultant next week, although I’m not sure how much benefit this will have, as it is only an initial consultation.
At least the rear wall (in the slope) will be made of reinforced concrete. Additionally, a supporting wall will be built centrally here, which in my opinion is also reinforced concrete.
We had seven companies present their offers in a roadshow format. The provider who claimed the disposal/deposit fees were significantly underestimated was actually a franchisee. I think we are talking about the same company.
However, we noticed similar statements from almost all providers. We were slowly getting desperate. Our idea was a city villa with a basement. I already suspected that we could have problems with perched water, which would make building a basement difficult (watertight concrete shell).
We were referred to our construction company by recommendation. Unlike the other companies, a construction engineer — not a salesperson — came to us. He had inspected the plot before our meeting (the plot is flat at the front, then there is a 3 m (10 feet) embankment and then flat again). Since he also suspected perched water — later confirmed by the geotechnical report — he made us an alternative proposal. We liked this proposal immediately. In our initial ideas, I had vaguely noticed that the terrace would have to be built directly into the slope (great view) but never really pursued it. He immediately recognized this and solved it with a build into the slope (terrace now on the ground floor).
The salespeople did not address these problems and concerns (even though we had partly taken pictures of the plot), but just stuck to their sales pitch. Only when reading the construction documents did we realize what was missing. Our construction company actually includes most of the additional costs or explicitly points them out to us.
As you can see, I do believe that after a long search we have found a reasonable building partner. But it’s better to ask a bit too much than too little.
Best regards from the Mosel-Saar region.
f-pNo
thanks for the information.
At the beginning, I need to point out again that I am a layperson. Therefore, I am not sure if I have correctly assigned the abbreviations used.
Ht = heating technology
qp = according to Google, this could mean quality inspection
Of course, I am aware that the KfW requirements are based on a combination of heating technology and insulation, windows, doors, etc. However, I do not know how each factor individually influences the outcome (other than the simplified understanding that if you reduce one element, you have to increase another to achieve a similar standard).
@Jaydee
We had researched this topic a lot beforehand and often read that although air-to-water heat pumps are officially designed for temperatures down to -15°C (5°F), they often struggle below -10°C (14°F). Therefore, although they are cheaper, we decided against these systems.
Bauexperte schrieb:
This guy is really funny
Am I correct in assuming that no heat demand calculation has been produced? Or in other words, that there is no technical building equipment (TBE) planning yet, nor planned, and that no heating load calculation has been commissioned or will be? You can only decide which heat generator (HG) should ultimately be used after receiving an exact calculation. This calculation also determines the amount and location of insulation needed. Only then can it be assessed whether and, if so, how much insulation can be omitted in certain areas without detrimental effects or with acceptable compromises.
Statements like “we’ll leave something out here, that’ll work” are not very productive and remind me of the old gas/water/plumbing guys who roughly estimated the size of the boiler by eyeballing it.
So far, there actually is no heat demand calculation. However, his suggestion of geothermal heating (he mostly builds with geothermal systems) was very appealing to us since we were thinking along the same lines. He also gave us a rough figure (I don’t currently have the documents at hand, so I’m writing from memory) — he assumes an energy demand of 50 watts per square meter. That means we need a pump with 8.5 kW capacity (if I calculated correctly).
Regardless, his remark about “giving up the KfW70 standard” is initially just a suggestion or food for thought. The problem is that I can’t really understand how maintaining insulation for KfW70 or dropping that standard would affect consumption. Consequently, I can’t fully grasp the sense or nonsense of this measure. I have scheduled an appointment with an energy consultant next week, although I’m not sure how much benefit this will have, as it is only an initial consultation.
Bauexperte schrieb:
What exactly do you mean here: “the cladding of reinforced concrete parts will be done with about 2 cm less polystyrene” ? Will the basement be constructed from reinforced concrete?
At least the rear wall (in the slope) will be made of reinforced concrete. Additionally, a supporting wall will be built centrally here, which in my opinion is also reinforced concrete.
Bauexperte schrieb:
And out of purely professional curiosity: are you building with a franchisee? That would explain your comment in the other thread regarding the incomplete listing of additional construction costs.
We had seven companies present their offers in a roadshow format. The provider who claimed the disposal/deposit fees were significantly underestimated was actually a franchisee. I think we are talking about the same company.
However, we noticed similar statements from almost all providers. We were slowly getting desperate. Our idea was a city villa with a basement. I already suspected that we could have problems with perched water, which would make building a basement difficult (watertight concrete shell).
We were referred to our construction company by recommendation. Unlike the other companies, a construction engineer — not a salesperson — came to us. He had inspected the plot before our meeting (the plot is flat at the front, then there is a 3 m (10 feet) embankment and then flat again). Since he also suspected perched water — later confirmed by the geotechnical report — he made us an alternative proposal. We liked this proposal immediately. In our initial ideas, I had vaguely noticed that the terrace would have to be built directly into the slope (great view) but never really pursued it. He immediately recognized this and solved it with a build into the slope (terrace now on the ground floor).
The salespeople did not address these problems and concerns (even though we had partly taken pictures of the plot), but just stuck to their sales pitch. Only when reading the construction documents did we realize what was missing. Our construction company actually includes most of the additional costs or explicitly points them out to us.
As you can see, I do believe that after a long search we have found a reasonable building partner. But it’s better to ask a bit too much than too little.
Best regards from the Mosel-Saar region.
f-pNo
B
Bauqualle18 Jun 2013 15:53Bauexperte schrieb:
I see this as the biggest obstacle, as the insulation craze will not decrease in the coming years; the outlook on the Energy Saving Ordinance 2014 already confirms this. ... you are absolutely right .. this law is already notorious as a "lobbyist law," there are plenty of articles about it on the internet, and hardly anyone takes into account the total financing costs as well as the operating, maintenance, and repair costs. Furthermore, the full "thermal envelope" completely excludes and hardly utilizes passive energy during the so-called transition phase. In addition, reports about mold infestation and rot in living spaces and the related health problems are becoming increasingly common .. but I don’t want to exaggerate nowQuick update: I have emailed our builder and requested a calculation of the heating demand. One version includes all the "components" for KfW 70, and another takes into account the changes he suggested. I hope that with this calculation, I can use the basics to figure out and estimate from which point such a measure becomes worthwhile. – I’m still open to any further tips. (What’s going on with the reply function today? I can’t create paragraphs by pressing Enter, and typed characters keep disappearing :mad)
f-pNo schrieb:
Ht = heating technology
qp = could mean quality control according to Google Brine heat pump => yes
Ht`(W/m²K) => specific transmission heat loss, respectively: Energy Saving Ordinance, KfW requirement value, calculated actual value
qp´´ (kWh/m²) specific annual primary energy demand, respectively: Energy Saving Ordinance, KfW requirement value, calculated actual value
Both based on AN (fictional calculation parameter)
f-pNo schrieb:
..., although air-water heat pumps are officially designed to operate down to -15 degrees, they often already fail below -10 degrees. Nonsense in general! f-pNo schrieb:
..he also gave us (I don’t have the documents at hand right now, so I can only recall from memory) an assumed energy demand of 50 watts per square meter. Where does he get that from? Probably a clairvoyant. That would make DIN 12831 obsolete right away. f-pNo schrieb:
..independent of that, his comment about “giving up the KfW70 standard” is initially only a suggestion/a thought experiment. Possibly it’s not even necessary. f-pNo schrieb:
..the problem is that unfortunately I can’t understand how keeping the insulation for the KfW70 standard or abandoning it would affect consumption. Even so-called experts have problems with that. f-pNo schrieb:
..I am already of the opinion that after a long search we have found a reasonable construction partner. That may be true from the builder’s side, but that does not make him a KfW optimizer or MEP planner! Best regards
B
Bauexperte20 Jun 2013 13:09Hello,
A storey with sloped roof surfaces is considered a full storey if more than three-quarters of its floor area has a height of 2.30 m (7.5 feet) or more. This is typically the case when high knee walls are installed. The exterior appearance often still looks like a single-storey building to the layperson, but mathematically it is counted as a two-storey building. This often causes disputes between sales departments and the building authority when single-storey construction is strictly required.
Best regards, Bauexperte
Shism schrieb:
As far as I know, the definition of a full storey does not depend on whether there are sloped ceilings, but on the living area compared to the floor below.
A storey with sloped roof surfaces is considered a full storey if more than three-quarters of its floor area has a height of 2.30 m (7.5 feet) or more. This is typically the case when high knee walls are installed. The exterior appearance often still looks like a single-storey building to the layperson, but mathematically it is counted as a two-storey building. This often causes disputes between sales departments and the building authority when single-storey construction is strictly required.
Best regards, Bauexperte
f-pNo schrieb:
Quote from BuildingExpert: What exactly do you mean by "the cladding of the reinforced concrete parts will be done with about 2 cm less styrofoam"? Will the basement be constructed from reinforced concrete?
End quote.
At least the rear wall (against the slope) will be made of reinforced concrete. Additionally, a central support wall will be added here, which in my opinion will also be made of reinforced concrete. I need to correct this. We had another discussion over the weekend. The reinforced concrete parts referred to (regarding the styrofoam insulation) are the two reinforced concrete slabs (basement to ground floor; ground floor to upper floor).
f-pNo schrieb:
There is currently no calculation of heating demand. I also asked for a heating demand calculation based on that remark. Over the weekend, I received an (in my view reasonable) explanation as to why this has not been done yet.
Since the house in its final form (dimensions, square meters, etc.) was not yet definitively fixed until last weekend, but was still being changed, the corresponding calculation could not be made. From my point of view, this is understandable—you need to know whether to calculate the heating demand for 190 or (now probably final) 170 square meters.
The preliminary house design is now being sent back to the structural engineer for a "final check." Afterwards, the heating/energy demand calculation will be carried out.
Then it should also be clear which measures will actually be implemented or not, and what their impact will be.
Building a house is definitely exciting—especially as a layperson, when you keep encountering new points to clarify. Personally, before opening this topic, I assumed we were already close to submitting the building permit/planning application. With the current checks and calculations being carried out, as well as the possible resulting changes, I can imagine that the process will still take some time. Exciting, but also frustrating (I was hoping to start construction in July—I guess I can forget about that).
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