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
B
Bauexperte17 Jun 2013 14:46Hello,
first of all, a single-family house built according to the Energy Saving Ordinance— you probably mean the Energy Saving Ordinance 2009— is not a bad house. There are countless posts on this topic; I myself have written about it hundreds of times. But why would you want to do that?
Whatever you decide—I can only advise you to design the building envelope to meet the KfW 70 standard and to install underfloor heating. Then, if you want to save costs by giving up the geothermal heat pump, you can later easily replace the existing heat generator with a geothermal heat pump or other new technologies.
Maybe you should consider, for example, giving up the double garage in the basement. Extensive measures are required here to isolate the garage and its odors/noises from the living areas. In my opinion, the cost savings from this would exceed the €8,000 your builder mentioned as savings from changing the insulation. And if you have more funds later, you can always have a prefabricated garage installed—provided the hillside location allows this.
Best regards, Bauexperte
first of all, a single-family house built according to the Energy Saving Ordinance— you probably mean the Energy Saving Ordinance 2009— is not a bad house. There are countless posts on this topic; I myself have written about it hundreds of times. But why would you want to do that?
f-pNo schrieb:Not exactly a small house
We are planning a house with approximately 170-190 sqm (1830-2045 sq ft) of living space, which in the basement (built partially above ground into a hillside) will include two smaller rooms, a utility room, and a double garage. The house will be heated using geothermal energy.
f-pNo schrieb:Are you sure you understood him correctly, or was his comment more about the potential savings from the geothermal heat pump? By the way—there are many ways to achieve KfW 70!
Our builder has now suggested that we reconsider the planned KfW 70 standard, as the additional investments would only pay off over a very long term (30 to 50 years).
f-pNo schrieb:I can only assume that your builder’s statement refers to the geothermal heat pump, which costs significantly more than “conventional” systems. Even so, his claim of “50 years” is questionable; nobody knows yet how long these new technologies will actually last.
Nevertheless, I struggle with giving 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 statement about up to 50 years accurate?)
f-pNo schrieb:It is quite possible that a standard loan would be more advantageous for you. You should discuss this with your financial advisor, as it depends on your personal situation and cannot be transferred one-to-one.
- The KfW financing has about 1% lower interest than a standard loan with a 10-year fixed rate—meaning on €50,000 you would save around €4,500 in interest over 10 years.
f-pNo schrieb:I see this as the biggest obstacle, since the demand for insulation will not decrease in the coming years; the outlook for the Energy Saving Ordinance 2014 already confirms this.
- giving up the KfW 70 standard could reduce the potential resale value
Whatever you decide—I can only advise you to design the building envelope to meet the KfW 70 standard and to install underfloor heating. Then, if you want to save costs by giving up the geothermal heat pump, you can later easily replace the existing heat generator with a geothermal heat pump or other new technologies.
Maybe you should consider, for example, giving up the double garage in the basement. Extensive measures are required here to isolate the garage and its odors/noises from the living areas. In my opinion, the cost savings from this would exceed the €8,000 your builder mentioned as savings from changing the insulation. And if you have more funds later, you can always have a prefabricated garage installed—provided the hillside location allows this.
Best regards, Bauexperte
Hello construction expert,
thank you very much for your feedback.
Oh, I see — until now I thought the new Energy Saving Ordinance was already in effect, and from your comment I realized that it is now called Energy Saving Ordinance 2014.
I am aware that a house built according to the current Energy Saving Ordinance is better compared to older houses, but maybe the KfW70 standard is even better.
It wasn’t planned that big at first. Actually, 130 sq m (1400 sq ft) plus an office in the basement. Due to the risk of groundwater pressure, the basement was moved above ground, which also solved the issue with the slope and terrace. When considering the size, you have to take into account that the upper floor has knee walls of 75 cm (30 inches) height (cannot be higher due to building regulations [eaves height]), which reduces the actual living space there. Also, because of the insulation, the utility room is counted as living space.
Geothermal heat pump = geothermal heat pump?
The geothermal heat pump is included as the heating system in both models.
As I understand it, if the described insulation options are reduced or omitted, more heating will be needed. If the insulation is done to KfW70 standard, you would save this additional heating effort. According to the builder’s information, however, this saving (from KfW70 insulation) would not cover the extra costs (>8,000 euros) for decades (30 / 50).
Sorry — I’m an amateur who has been trying to get to grips with all this for months.
The building envelope (Ytong masonry with 36.5 cm (14 inches) blocks) will remain as planned for KfW70. Underfloor heating will also be installed — according to information and various research, it is the most sensible heating option with geothermal systems.
The idea (including garage + carport) has already been discarded due to space constraints.
(I hope I quoted everything correctly)
Regards
f-pNo
thank you very much for your feedback.
Bauexperte schrieb:
You probably mean the Energy Saving Ordinance 2009
Oh, I see — until now I thought the new Energy Saving Ordinance was already in effect, and from your comment I realized that it is now called Energy Saving Ordinance 2014.
I am aware that a house built according to the current Energy Saving Ordinance is better compared to older houses, but maybe the KfW70 standard is even better.
Bauexperte schrieb:
Not exactly a small house
It wasn’t planned that big at first. Actually, 130 sq m (1400 sq ft) plus an office in the basement. Due to the risk of groundwater pressure, the basement was moved above ground, which also solved the issue with the slope and terrace. When considering the size, you have to take into account that the upper floor has knee walls of 75 cm (30 inches) height (cannot be higher due to building regulations [eaves height]), which reduces the actual living space there. Also, because of the insulation, the utility room is counted as living space.
Bauexperte schrieb:
Are you sure you understood him correctly, or was his comment more about potential savings with the geothermal heat pump?
Geothermal heat pump = geothermal heat pump?
The geothermal heat pump is included as the heating system in both models.
As I understand it, if the described insulation options are reduced or omitted, more heating will be needed. If the insulation is done to KfW70 standard, you would save this additional heating effort. According to the builder’s information, however, this saving (from KfW70 insulation) would not cover the extra costs (>8,000 euros) for decades (30 / 50).
Sorry — I’m an amateur who has been trying to get to grips with all this for months.
Bauexperte schrieb:
Whatever you decide — I can only advise you to design the building envelope to meet KfW70 standard and to install underfloor heating.
The building envelope (Ytong masonry with 36.5 cm (14 inches) blocks) will remain as planned for KfW70. Underfloor heating will also be installed — according to information and various research, it is the most sensible heating option with geothermal systems.
Bauexperte schrieb:
Maybe you should consider giving up the double garage in the basement. Later, when you have more funds available, you can always add a prefabricated garage — provided the slope allows it.
The idea (including garage + carport) has already been discarded due to space constraints.
(I hope I quoted everything correctly)
Regards
f-pNo
Hello,
The KfW definitions do not refer solely to the building envelope or to the technical systems. Certain limit values must be met for both (Ht´ and qp´´)!
The statement from the general contractor/main contractor is amusing. However, it is true that when using a brine heat pump, the impact of insulation on heating consumption is reduced. How much and to what extent can only be determined once the actual demand (power, energy) is known.
These basics seem to be missing here, as is often the case.
Best regards
f-pNo schrieb:The issue of the “Energy Saving Ordinance” has already been clarified by the building expert.
...What are your thoughts on this?...
The KfW definitions do not refer solely to the building envelope or to the technical systems. Certain limit values must be met for both (Ht´ and qp´´)!
The statement from the general contractor/main contractor is amusing. However, it is true that when using a brine heat pump, the impact of insulation on heating consumption is reduced. How much and to what extent can only be determined once the actual demand (power, energy) is known.
These basics seem to be missing here, as is often the case.
Best regards
B
Bauexperte18 Jun 2013 00:42Hello,
Am I right in assuming that no calculation of the heating demand has been made? Or in other words, that there is no technical building services planning yet, no heating load calculation ordered or planned? Only after a precise calculation is presented can you decide which heat generator (HG) will ultimately be used. This calculation also defines the amount and location of insulation required. Only with this information can it be determined whether, where, and to what extent insulation can be reduced, and at what cost or detriment, or if it is not advisable at all.
Statements like “let’s omit this here, then it should be fine” are not very constructive and remind me of the gas/water/“whatever” guys from long ago who sized boilers roughly by rule of thumb.
What exactly do you mean here: “the cladding of the reinforced concrete parts will be done with about 2 cm (0.8 inches) less Styrofoam”? Is the basement being constructed with reinforced concrete?
And just out of professional curiosity: are you building with a franchisee? That would explain your statement in the other thread regarding the incompletely specified additional building costs.
Best regards, Bauexperte
f-pNo schrieb:You’re welcome
Thank you very much for your feedback.
f-pNo schrieb:It is planned to come into effect in 2014 – although what exactly will be verified in it is (so far) known only to the heavens… and whether it will pass all committees by then is still uncertain. But a name is needed, so everyone calls it Energy Saving Ordinance 2014 for now. This means that until then, all building projects must comply with the currently valid Energy Saving Ordinance 2009.
Oh, I see – until now I thought the new Energy Saving Ordinance was already in effect, and based on your note I realized it is now called Energy Saving Ordinance 2014.
f-pNo schrieb:So you’re planning a (above-ground) basement, a ground floor, and an attic floor. It is only called an upper floor if it is a full storey, i.e., without sloping ceilings.
Regarding the size specification, you have to consider that the upper floor has knee walls of 75cm (30 inches) height (more is not possible due to building regulations [height of eaves]), which reduces the actual living area there. Also, due to insulation, etc., the utility room is counted as living space.
f-pNo schrieb:Yes.
Ground source heat pump = Geothermal heat pump?
f-pNo schrieb:That guy is really amusing
The geothermal heat pump is included as heating technology in both models.
As I understand it, if the described insulation options are reduced or omitted, more heating is required. If the insulation is built to KfW70 standard, this additional heating effort could be avoided. According to information from the building consultant, the savings (with KfW70 insulation) would only recover the additional costs (>8,000 euros) after many years (30 / 50).
Am I right in assuming that no calculation of the heating demand has been made? Or in other words, that there is no technical building services planning yet, no heating load calculation ordered or planned? Only after a precise calculation is presented can you decide which heat generator (HG) will ultimately be used. This calculation also defines the amount and location of insulation required. Only with this information can it be determined whether, where, and to what extent insulation can be reduced, and at what cost or detriment, or if it is not advisable at all.
Statements like “let’s omit this here, then it should be fine” are not very constructive and remind me of the gas/water/“whatever” guys from long ago who sized boilers roughly by rule of thumb.
f-pNo schrieb:No problem, we’re gradually getting there
Sorry – I’m a layperson who has been trying to understand the whole topic for months.
f-pNo schrieb:By building envelope I mean the entire building including insulation, windows, roof covering, and exterior plaster!
The building envelope (Ytong masonry with 36.5cm (14 inches) blocks) remains as planned for KfW70. Underfloor heating will also be installed – according to information and various research, the most sensible heating option when using geothermal energy.
What exactly do you mean here: “the cladding of the reinforced concrete parts will be done with about 2 cm (0.8 inches) less Styrofoam”? Is the basement being constructed with reinforced concrete?
And just out of professional curiosity: are you building with a franchisee? That would explain your statement in the other thread regarding the incompletely specified additional building costs.
f-pNo schrieb:You did
(I hope I managed the quotes correctly)
Best regards, Bauexperte
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