ᐅ Build a Single-Family Home to KfW55 or Efficiency House 70 Standards?
Created on: 27 Dec 2019 20:24
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Sternchen31
Hello everyone,
we hope you can help us a bit. We have purchased a plot of land, the notarization appointment has already taken place, and now we are waiting for the payment deadline. Meanwhile, we are already in contact with several solid construction companies that we have shortlisted and have received two offers so far; the third meeting was today.
So far, it was clear to us that we would build a KfW 55 single-family house (about 125 m² (1350 sq ft) living space on the ground floor and first floor) with a full basement (30 m² (320 sq ft) basement possibly used as living space with underfloor heating), a photovoltaic system, heat pump, and underfloor heating with individual room control.
Today, for the first time, we were asked why we actually want to build to KfW 55 standards. An efficiency house 70 would be around €20,000 - 30,000 cheaper, plus approximately €15,000 for the photovoltaic system. According to this, it would take about 15–20 years for the additional costs of building to KfW 55 with a photovoltaic system to be recovered through energy savings. The subsidies, except for the €5,000 from KfW, are no longer as favorable as they used to be and may not be cost-effective.
We have already received two offers from construction companies where this question about not building to KfW 70 did not come up at all.
We are now a bit confused and would like to exchange some thoughts on this.
Many thanks in advance.
we hope you can help us a bit. We have purchased a plot of land, the notarization appointment has already taken place, and now we are waiting for the payment deadline. Meanwhile, we are already in contact with several solid construction companies that we have shortlisted and have received two offers so far; the third meeting was today.
So far, it was clear to us that we would build a KfW 55 single-family house (about 125 m² (1350 sq ft) living space on the ground floor and first floor) with a full basement (30 m² (320 sq ft) basement possibly used as living space with underfloor heating), a photovoltaic system, heat pump, and underfloor heating with individual room control.
Today, for the first time, we were asked why we actually want to build to KfW 55 standards. An efficiency house 70 would be around €20,000 - 30,000 cheaper, plus approximately €15,000 for the photovoltaic system. According to this, it would take about 15–20 years for the additional costs of building to KfW 55 with a photovoltaic system to be recovered through energy savings. The subsidies, except for the €5,000 from KfW, are no longer as favorable as they used to be and may not be cost-effective.
We have already received two offers from construction companies where this question about not building to KfW 70 did not come up at all.
We are now a bit confused and would like to exchange some thoughts on this.
Many thanks in advance.
B
boxandroof27 Dec 2019 22:41The subsidy for KfW55 is relatively low and therefore not a particularly attractive target. The question is how good or bad the insulation standard is without KfW support and what payback period is acceptable for you.
If you determine the H’t value for both options, you can use it to estimate and roughly calculate the payback period. This value describes the insulation quality without influence from technology or other adjustments. Alternatively, look at which building components are specifically improved and what the insulation values are for each.
Photovoltaic systems are generally cost-effective; the installed area should be as large as possible to maximize the return. Homebuilders are not necessarily the best partners for photovoltaic systems, so I would recommend planning and installing them separately. Make sure to provide a conduit to the roof. Installing a system that is just barely large enough to qualify for a subsidy would be a mistake.
If you determine the H’t value for both options, you can use it to estimate and roughly calculate the payback period. This value describes the insulation quality without influence from technology or other adjustments. Alternatively, look at which building components are specifically improved and what the insulation values are for each.
Photovoltaic systems are generally cost-effective; the installed area should be as large as possible to maximize the return. Homebuilders are not necessarily the best partners for photovoltaic systems, so I would recommend planning and installing them separately. Make sure to provide a conduit to the roof. Installing a system that is just barely large enough to qualify for a subsidy would be a mistake.
A photovoltaic system has hardly anything to do with KfW 55. Using a heat pump instead of, for example, gas would be more beneficial.
€15,000 for a photovoltaic system with a maximum of 10 kWp would be too expensive anyway. Additionally, there could be tax issues if the general contractor does not provide a separate invoice for it.
€15,000 for a photovoltaic system with a maximum of 10 kWp would be too expensive anyway. Additionally, there could be tax issues if the general contractor does not provide a separate invoice for it.
boxandroof schrieb:
Home builders are not necessarily the best partners for photovoltaic systems; I would plan and install them separately. Provide conduit to the roof. Installing a system that is just barely large enough for a subsidy would be a mistake.Similarly, residential builders are not always the best partners for systems where efficiency is key. Every system is only as good as its design and sizing, and servicing a batch size of "one dwelling unit" sometimes sets a tight limit for achieving optimal efficiency – on the other hand, detached single-family homes are only partially suitable for systems designed for multiple units.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Sternchen31 schrieb:
Today, we were asked for the first time why we actually want to build to KfW55 standards. An Efficiency House 70 would be about €20,000 to €30,000 cheaper, plus around €15,000 for the photovoltaic system.How do you arrive at these additional costs?! In 2016, upgrading from KfW70 to KfW55 cost us only about €4,500 for the entire house (a bit more insulation and better insulation under the concrete slab). On top of that, there was a grant of €5,000, so it worked out well.
Our basement is almost completely underground (rock), and only the hallway/entrance area has underfloor heating, but all rooms have mechanical ventilation with heat recovery. The performance was good enough to easily meet the KfW55 standard.
blackm88 schrieb:
In 2016, upgrading from KfW70 to KfW55 cost us only about €4,500 for the entire house. Then the standard features without the upgrade were probably quite close to the threshold; a full step up would likely have been somewhat more expensive.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
11ant schrieb:
Then the standard features without the upgrade were probably just around the threshold; a full grade jump would likely have been somewhat more expensive. If a heat pump is already installed, the primary energy issue is resolved.
If exterior insulation and finish system (EIFS) or a cavity wall construction is used, it only requires a few centimeters more insulation, possibly a slight improvement in the windows (although one can compensate for the other).
If the building is constructed with wood, the wall assembly usually meets KfW 55 or better standards.
Five-figure additional costs are only to be expected in the following situation:
Monolithic construction heated with gas.
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