Hello everyone,
we are currently planning our house and are considering whether the extra cost from KfW55 to KfW40 plus is "worth it." By worth it, I mean both the payback period and, of course, other advantages and disadvantages, such as a central ventilation system versus a decentralized one.
Our general contractor offers the following standard options (alternatives are possible in consultation):
My specific questions are:
1) What potential savings can be expected due to lower heating costs, electricity costs, and feed-in tariffs, assuming energy price increases, maintenance, repairs, or total failure of components are excluded? I understand that many factors play a role and this is hard to calculate, but perhaps it is possible to give at least a rough range based on comparison values and considering the following information:
2) What other advantages and disadvantages exist between KfW40 plus and KfW55?
3) Any further tips on how to make a good decision?
Thank you very much in advance for your assessment!
J.
we are currently planning our house and are considering whether the extra cost from KfW55 to KfW40 plus is "worth it." By worth it, I mean both the payback period and, of course, other advantages and disadvantages, such as a central ventilation system versus a decentralized one.
Our general contractor offers the following standard options (alternatives are possible in consultation):
- KfW 55 (no extra cost): aerated concrete blocks 36.5 cm (14 inches), air-to-water heat pump, underfloor heating, decentralized ventilation system
- KfW 40 plus (€25,000 surcharge): aerated concrete blocks 42.5 cm (17 inches), air-to-water heat pump, underfloor heating, central ventilation system, photovoltaic system + energy storage
My specific questions are:
1) What potential savings can be expected due to lower heating costs, electricity costs, and feed-in tariffs, assuming energy price increases, maintenance, repairs, or total failure of components are excluded? I understand that many factors play a role and this is hard to calculate, but perhaps it is possible to give at least a rough range based on comparison values and considering the following information:
- The house is located in NRW (mild climate)
- Roof orientation and pitch are almost ideal for photovoltaic
- The house has no basement and with the 42.5 cm (17 inches) blocks a living area of 190 m² (2045 sq ft)
- 2 adults and 2 small children
- 3 kWp photovoltaic system, 6.5 kWh battery (assumed)
- Indoor temperature about 23°C (73°F), bedrooms about 21°C (70°F)
- I am aware of the additional KfW funding options; however, the interest rate of the KfW loan is less favorable than that of our bank, so the advantage would be reduced to €8,150
2) What other advantages and disadvantages exist between KfW40 plus and KfW55?
3) Any further tips on how to make a good decision?
Thank you very much in advance for your assessment!
J.
The forum has a search function: by using the term KfW40, you will likely find useful information here. This topic is discussed every month.
You can roughly estimate the savings by comparing 55% and 40%.
For heating costs of 100 euros a month in a KfW100 house, you save about 15 euros per month when moving from 55% to 40%.
You can roughly estimate the savings by comparing 55% and 40%.
For heating costs of 100 euros a month in a KfW100 house, you save about 15 euros per month when moving from 55% to 40%.
Thank you very much for all the helpful replies.
The photovoltaic system and storage are NOT included in the general contractor’s offer, but are my own estimated figures – sorry for the confusion.
I will proceed as follows:
We will see from there …
The photovoltaic system and storage are NOT included in the general contractor’s offer, but are my own estimated figures – sorry for the confusion.
I will proceed as follows:
- Ask the general contractor for details regarding the photovoltaic system and storage
- Request a breakdown of the additional costs for KfW40 plus according to: extra insulation, photovoltaic system, storage, centralized ventilation system, and other items (if there are any additional components)
- Have the maximum possible photovoltaic system calculated and get an offer for it
- Request a quote for the preparation work for a photovoltaic system (e.g., cable duct) to allow the photovoltaic system to potentially be contracted out separately. This shouldn’t be expensive, but the inquiry might encourage the general contractor to provide a more attractive offer
We will see from there …
ypg schrieb:
You can roughly estimate the savings by comparing 55% to 40%.
For heating costs of 100 (currency) in a KfW 100 house, you save about €15 per month by reducing from 55 to 40. The original reference behind the 55 and 40 values is the primary energy demand, which however
1) only represents a maximum limit
2) does not provide meaningful information regarding heating costs, as it is primarily politically determined (and therefore essentially arbitrary)
A basic house with insulation at Passive House standard but equipped with a gas boiler may not even reach KfW 70 on paper, yet its annual heating costs are unlikely to exceed €400. On the other hand, a KfW 55 new build with an air-to-water heat pump combined with an improperly sized underfloor heating system meets the funding criteria on paper but can easily result in annual heating costs of €1,500 for the occupants.
@Te
I would approach it as @Joedreck suggested: If you are planning to have both photovoltaic systems and a centralized mechanical ventilation system with heat recovery anyway, the additional cost of about €17,000 is acceptable. If you only want one of these, it's better to stick with KfW 55 and outsource the other separately.
I see it more like this, because
None of the KfW options will be economically profitable. You should be clear about that.
John333 schrieb:
Hello everyone,
we are currently planning our house and are considering whether the additional cost from KfW55 to KfW40 plus is "worth it." By worth it, I mean both the payback period and, of course, other advantages and disadvantages, such as a central ventilation system versus a decentralized ventilation system.
Our general contractor offers the following options as standard (alternatives are possible by arrangement):
- KfW 55 (no extra cost): aerated concrete blocks 36.5 cm (14 inches), air-to-water heat pump, underfloor heating, decentralized ventilation system
- KfW 40 plus (25,000€ extra cost): aerated concrete blocks 42.5 cm (17 inches), air-to-water heat pump, underfloor heating, central ventilation system, photovoltaic system + energy storage
My specific questions are:
1) What savings potential can be expected from lower heating costs, electricity costs, and feed-in tariffs, assuming price increases for energy, maintenance, and repairs / total failure of components are not considered? I understand that many factors play a role here and it is hardly possible to calculate this precisely, but perhaps it is possible to give a rough range based on comparison values and considering the following details:
- The house is located in NRW (mild climate)
- Roof orientation / pitch is almost ideal for photovoltaic
- The house has no basement and with the 42.5 cm blocks has a living area of 190 m² (2045 sq ft)
- 2 adults and 2 small children
- 3 kWp photovoltaic system, 6.5 kWh battery (assumed)
- Indoor temperature approx. 23°C (73°F), bedrooms approx. 21°C (70°F)
- I am aware of the additional KfW funding opportunities; however, the interest rate of the KfW loan is less favorable than our bank’s rate, so the benefit would be reduced to 8,150€.
2) What other advantages and disadvantages arise between KfW40 plus and KfW55?
3) Any further tips on how to reach a good decision?
Thanks in advance for your assessment!
J.
None of the KfW options will be economically profitable. You should be clear about that.
John333 schrieb:
Thank you very much for the many helpful responses.
The photovoltaic system and battery storage are NOT included in the general contractor’s offer but are my own estimated figures – sorry for the confusion.
I will now do the following:
- Ask the general contractor for details on the photovoltaic system and battery storage
- Request a breakdown of the additional costs for KfW40 Plus by: extra insulation, photovoltaic system, battery storage, central ventilation system, and other items (in case there are additional charges)
- Have the largest possible photovoltaic system calculated and an offer prepared
- Request an offer for the preparation of a photovoltaic system (e.g., cable duct) so that the photovoltaic system can possibly be contracted externally. This shouldn’t cost much but maybe asking will lead the general contractor to provide a more attractive offer
Then we will see further... You don’t have to go into that much detail.
What’s interesting is which photovoltaic system is being installed. If you get a system with 5 kWp and a 5 kW battery, that’s roughly worth 10,000–15,000 euros net. A ventilation system adds about 5,000–10,000 euros extra.
You’ll pay around 25,000 euros more, receive 10,000 euros in subsidies, leaving 15,000 euros out of pocket. But you will get up to 25,000 euros back through technology savings, heating/hot water cost reductions, photovoltaic tax refunds, peace of mind, thicker walls, and so on.
As I said, it’s important to know which photovoltaic system is being installed. You will also need a separate invoice for tax refund purposes.
Because, mathematically speaking, a 2.5 kWp photovoltaic system and a 2.5 kW battery would be sufficient for KfW40 Plus. But that would be nonsense. I would have that cost removed and subcontracted externally.
Hello everyone,
I have obtained the missing information from the general contractor:
So the KfW 40 plus package probably does not make economic sense for us.
I will now request quotes for a turnkey photovoltaic system as large as possible.
Do you have any tips on how to find suppliers who provide high-quality work?
I have obtained the missing information from the general contractor:
- Photovoltaic system + storage: Minimum according to KfW requirements, which for us is about 2.7 kWp
- Additional costs broken down (net):
- Photovoltaic system + storage: €13,000
- 42.5 cm (17 inches) solid block + additional insulation: €8,000
- The central ventilation system was already included in the price, so it is not part of the extra costs for KfW 40 plus! Of course, leaving it out would save about €4,000.
So the KfW 40 plus package probably does not make economic sense for us.
I will now request quotes for a turnkey photovoltaic system as large as possible.
Do you have any tips on how to find suppliers who provide high-quality work?
John333 schrieb:
Thank you very much for all the helpful answers.
Photovoltaic system + storage are NOT included in the general contractor’s offer, but rather my estimated figures – sorry for the confusion.
I will now do the following:
- Ask the general contractor for details on photovoltaic system + storage
- Request a breakdown of the additional costs for KfW 40 plus by: additional insulation, photovoltaic system, storage, central ventilation system, others (in case there are any further items)
- Have the maximum possible photovoltaic system calculated and a quote prepared
- Request an offer for preparing the photovoltaic system (e.g. conduits) so that the photovoltaic system could potentially be subcontracted separately. This should not be very expensive but might prompt the general contractor to make a more attractive offer themselves
We’ll see how it goes from there …
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