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robin19883 Apr 2019 21:47Hello everyone,
Even though the topic of the "right" building services technology and its various advantages has already been discussed extensively, I still cannot answer the general question of whether a KfW 40 plus house is truly advantageous for me.
In many parts of the forum, it is mentioned that, purely for economic reasons, the standard according to the Energy Saving Ordinance (EnEV) is recommended and that the additional costs for a KfW house generally do not pay off. I find this hard to understand.
We are currently planning the construction of a new single-family house built with solid construction, without a basement, with approximately 200 m² (2,150 sq ft) of living space and underfloor heating. Without going too much into detail (although general and undetailed comparisons are always difficult), I would like to present the following simplified calculation:
Additional costs for KfW 40 plus compared to the Energy Saving Ordinance standard:
Ground source heat pump (deep drilling): €12,000 (€20,000 instead of a gas boiler with solar system for €8,000)
Ventilation system with heat recovery: €12,000
Photovoltaic system with storage: €15,000
Total additional costs: €39,000
Subsidies:
Repayment waiver through KfW 40 plus: €15,000
BAFA subsidy for geothermal energy: €4,500
Remaining additional costs: €19,500
Is it really the case that these additional costs of €19,500 do not pay off over a reasonable period? (There are further costs for KfW 40 plus, for example for construction supervision; however, these are largely also subsidized, e.g. through the KfW 431 program).
Furthermore, a low-interest loan (currently 0.9%) of up to €100,000 can be obtained from KfW, and other banks do not treat KfW loans as regular loans, which additionally improves one’s creditworthiness.
Would you still say that, based on these figures, a KfW 40 plus house is not economically viable?
Thank you very much for your insights!
Even though the topic of the "right" building services technology and its various advantages has already been discussed extensively, I still cannot answer the general question of whether a KfW 40 plus house is truly advantageous for me.
In many parts of the forum, it is mentioned that, purely for economic reasons, the standard according to the Energy Saving Ordinance (EnEV) is recommended and that the additional costs for a KfW house generally do not pay off. I find this hard to understand.
We are currently planning the construction of a new single-family house built with solid construction, without a basement, with approximately 200 m² (2,150 sq ft) of living space and underfloor heating. Without going too much into detail (although general and undetailed comparisons are always difficult), I would like to present the following simplified calculation:
Additional costs for KfW 40 plus compared to the Energy Saving Ordinance standard:
Ground source heat pump (deep drilling): €12,000 (€20,000 instead of a gas boiler with solar system for €8,000)
Ventilation system with heat recovery: €12,000
Photovoltaic system with storage: €15,000
Total additional costs: €39,000
Subsidies:
Repayment waiver through KfW 40 plus: €15,000
BAFA subsidy for geothermal energy: €4,500
Remaining additional costs: €19,500
Is it really the case that these additional costs of €19,500 do not pay off over a reasonable period? (There are further costs for KfW 40 plus, for example for construction supervision; however, these are largely also subsidized, e.g. through the KfW 431 program).
Furthermore, a low-interest loan (currently 0.9%) of up to €100,000 can be obtained from KfW, and other banks do not treat KfW loans as regular loans, which additionally improves one’s creditworthiness.
Would you still say that, based on these figures, a KfW 40 plus house is not economically viable?
Thank you very much for your insights!
19,500 additional costs. The house with gas would have around $1,000 in gas costs per year and 2,000 kWh of electricity per year for two people, with more for three, and so on.
The KFW 40 Plus house saves the gas, so it breaks even after about 19.5 years, but due to the ground source heat pump and controlled mechanical ventilation, the electricity demand will likely double. So, in the end, you are clearly looking at around 30 years to break even. If you also consider the opportunity cost—if you had invested your 19,500 not in KFW 40 but in ETFs tracking the DAX or S&P over 30 years—it becomes completely unprofitable. K.
The KFW 40 Plus house saves the gas, so it breaks even after about 19.5 years, but due to the ground source heat pump and controlled mechanical ventilation, the electricity demand will likely double. So, in the end, you are clearly looking at around 30 years to break even. If you also consider the opportunity cost—if you had invested your 19,500 not in KFW 40 but in ETFs tracking the DAX or S&P over 30 years—it becomes completely unprofitable. K.
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bierkuh833 Apr 2019 22:53I have an energy efficiency standard house from 2016 and pay a monthly advance payment of 47€ (approximately $50) to the energy supplier for heating and hot water. Now you can also assume 50€ (about $53) and pretend your house doesn’t consume any energy at all.
P.S.
Keep in mind that the higher investment in the system incurs interest costs, lasting until the end of the loan term. Opportunity costs should also be considered.
The idea that a KFW loan (or equivalent green financing) offers better conditions is also a myth.
More technology also means higher maintenance costs (batteries, inverters, filter replacements, etc.) – difficult to quantify, varying from case to case, but the first two examples should need to be replaced at least once within your “payback period,” so now do the math.
P.S.
Keep in mind that the higher investment in the system incurs interest costs, lasting until the end of the loan term. Opportunity costs should also be considered.
The idea that a KFW loan (or equivalent green financing) offers better conditions is also a myth.
More technology also means higher maintenance costs (batteries, inverters, filter replacements, etc.) – difficult to quantify, varying from case to case, but the first two examples should need to be replaced at least once within your “payback period,” so now do the math.
In my opinion, it can also be viewed differently:
A controlled residential ventilation system with heat recovery is, in my eyes, very useful, and I wouldn’t want to do without it anymore. You have to decide if you want it or not. There are many discussions about this. A controlled residential ventilation system will never pay for itself; it has to be considered a luxury.
Photovoltaic systems without storage are profitable in most cases and typically pay off after about 10 years. And if you are already aiming for the KfW40 standard, you might as well go for KfW40+, as the storage system is included due to the higher subsidy.
Whether deep drilling makes sense for a KfW40 house is something to reconsider. You could also opt for surface collectors, ring trench collectors, etc., depending on whether you want or are able to do some of the work yourself. Alternatively, you could go straight for an air-to-water heat pump, although in that case, receiving funding from BAFA might be more challenging.
A controlled residential ventilation system with heat recovery is, in my eyes, very useful, and I wouldn’t want to do without it anymore. You have to decide if you want it or not. There are many discussions about this. A controlled residential ventilation system will never pay for itself; it has to be considered a luxury.
Photovoltaic systems without storage are profitable in most cases and typically pay off after about 10 years. And if you are already aiming for the KfW40 standard, you might as well go for KfW40+, as the storage system is included due to the higher subsidy.
Whether deep drilling makes sense for a KfW40 house is something to reconsider. You could also opt for surface collectors, ring trench collectors, etc., depending on whether you want or are able to do some of the work yourself. Alternatively, you could go straight for an air-to-water heat pump, although in that case, receiving funding from BAFA might be more challenging.
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robin19884 Apr 2019 08:03Thank you all for your responses!
What World-e is addressing are exactly the thoughts that are on my mind right now. Basically, it’s just one more system added each time to reach the next subsidy level. And especially if you believe that a mechanical ventilation system with heat recovery is indispensable in a new build (which seems to be the consensus in this forum, even though I had a different opinion until now), then achieving KfW 40 is not far off, and geothermal energy is almost “free” thanks to the subsidy (to put it simply).
My architect is quite convinced of deep drilling, and all his clients are highly satisfied with it (he is a close relative, so I have full trust). But of course, this topic is already heavily debated. Given the many other considerations, if we go for a heat pump, we would choose deep drilling.
However, combining this with a photovoltaic system would presumably result in a high degree of self-consumption of the electricity produced. Do you think this advantage is offset by the increased electricity demand from the heat pump and mechanical ventilation? Until now, I believed that with a properly sized photovoltaic system maximizing self-consumption, overall electricity costs can be reduced (despite the higher electricity demand), thus achieving a payback period well under 30 years.
These are of course important points. The additional interest at 0.9% on €19,500 is manageable. Regarding opportunity costs, you are absolutely right.
What World-e is addressing are exactly the thoughts that are on my mind right now. Basically, it’s just one more system added each time to reach the next subsidy level. And especially if you believe that a mechanical ventilation system with heat recovery is indispensable in a new build (which seems to be the consensus in this forum, even though I had a different opinion until now), then achieving KfW 40 is not far off, and geothermal energy is almost “free” thanks to the subsidy (to put it simply).
World-e schrieb:
You could certainly also go for surface collectors, horizontal trench collectors, etc., depending on whether you want or can do some of the work yourself. Or you could simply choose an air-to-water heat pump, but then the BAFA subsidy might be tight.
My architect is quite convinced of deep drilling, and all his clients are highly satisfied with it (he is a close relative, so I have full trust). But of course, this topic is already heavily debated. Given the many other considerations, if we go for a heat pump, we would choose deep drilling.
Nordlys schrieb:
The KfW 40 plus house saves on gas, break-even in 19.5 years, but due to the geothermal heat pump and mechanical ventilation with heat recovery, electricity demand will probably double. So in the end, you’re clearly looking at around 30 years until break-even.
However, combining this with a photovoltaic system would presumably result in a high degree of self-consumption of the electricity produced. Do you think this advantage is offset by the increased electricity demand from the heat pump and mechanical ventilation? Until now, I believed that with a properly sized photovoltaic system maximizing self-consumption, overall electricity costs can be reduced (despite the higher electricity demand), thus achieving a payback period well under 30 years.
bierkuh83 schrieb:
Remember that the higher investment in the system will accrue interest costs up to the end of the loan term. Also consider opportunity costs.
These are of course important points. The additional interest at 0.9% on €19,500 is manageable. Regarding opportunity costs, you are absolutely right.
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RotorMotor4 Apr 2019 08:04robin1988 schrieb:
Even though the topic of the “right” building systems and their various advantages has been discussed extensively, I still can’t answer the general question of whether a KFW 40 plus house is truly worth it for me. An interesting question that I have been thinking about for a while as well.
However, it is difficult to find concrete information.
robin1988 schrieb:
Additional costs for KFW 40 plus compared to the standard Energy Saving Ordinance:
Ground source heat pump (deep drilling): €12,000 (US$20,000 instead of gas boiler with solar for €8,000)
Mechanical ventilation with heat recovery: €12,000
Photovoltaic system with battery storage: €15,000
Total additional costs: €39,000
Subsidies:
Loan forgiveness through KFW 40 plus: €15,000
BAFA subsidy for geothermal energy: €4,500
Remaining additional costs: €19,500 I think you still missed some important points here, such as the higher planning effort and the building envelope with insulation, windows, etc.
For a large house like this (200m² (2,150 ft²)), I would estimate these costs at a minimum of €20,000.
For me, the result would actually be the same total amount after this adjustment:
Because I want mechanical ventilation anyway for comfort reasons, so that cost can be excluded from the comparison.
The photovoltaic system pays for itself, so it also doesn’t need to be included in the comparison.
I don’t really want gas in the house either, but you can’t just ignore it completely.
That leaves additional costs for planning, building envelope, battery storage, and heating system at around €30,000.
If everything goes well, you might break even after about 30 years.
For smaller houses, it could be cheaper, or with a separate apartment.
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