Hello everyone,
I’d like to briefly introduce our house project here. The goal is to exchange ideas with you on various topics and possibly create specific threads for detailed subtopics. Since we haven’t signed any contract yet and only have two initial rough quotes, I can’t provide details like heating load calculations at this stage. Thanks for your understanding.
Now for the first rough plan:
- Single-family house with about 170-180m² (1830-1940 sq ft) living space
- Bungalow
- Only the ground floor will be occupied
- Geothermal heating with 2 boreholes, each 80m (260 ft) deep, and a Nibe S1255 unit
- Floor slab insulation with glass gravel
- 36.5cm (14 inches) exterior walls made of Ytong masonry units
- Ceiling insulation using Ytong ceiling elements (maybe too expensive!?)
- Household of 2 people (likely to increase to 4)
- Decentralized ventilation (I’m not very satisfied with ReglerAir window units)
- Photovoltaic system on the roof, 7-10 kWp, without battery storage
- Triple-glazed PVC windows
I would appreciate your initial assessment and feedback.
Budget: Moderate, two incomes; total costs for the complete house (excluding furniture and kitchen) should not exceed 400,000 euros.
I will provide more information later.
Best regards and thanks for your feedback!
Peter
I’d like to briefly introduce our house project here. The goal is to exchange ideas with you on various topics and possibly create specific threads for detailed subtopics. Since we haven’t signed any contract yet and only have two initial rough quotes, I can’t provide details like heating load calculations at this stage. Thanks for your understanding.
Now for the first rough plan:
- Single-family house with about 170-180m² (1830-1940 sq ft) living space
- Bungalow
- Only the ground floor will be occupied
- Geothermal heating with 2 boreholes, each 80m (260 ft) deep, and a Nibe S1255 unit
- Floor slab insulation with glass gravel
- 36.5cm (14 inches) exterior walls made of Ytong masonry units
- Ceiling insulation using Ytong ceiling elements (maybe too expensive!?)
- Household of 2 people (likely to increase to 4)
- Decentralized ventilation (I’m not very satisfied with ReglerAir window units)
- Photovoltaic system on the roof, 7-10 kWp, without battery storage
- Triple-glazed PVC windows
I would appreciate your initial assessment and feedback.
Budget: Moderate, two incomes; total costs for the complete house (excluding furniture and kitchen) should not exceed 400,000 euros.
I will provide more information later.
Best regards and thanks for your feedback!
Peter
With your KFW40 standard and the standard outdoor temperature, you can easily achieve an annual performance factor between 4.55 and 4.60 using an air-to-water heat pump with a 30°C (86°F) flow temperature.
Anything else doesn’t make economic sense, and you also get a 30% subsidy. You will never recover the additional costs otherwise.
Edit:
I just noticed that you didn’t specify the standard outdoor temperature. For my statement, it should be between -10°C and -12°C (14°F and 10°F). Otherwise, it would need to be reconsidered.
Anything else doesn’t make economic sense, and you also get a 30% subsidy. You will never recover the additional costs otherwise.
Edit:
I just noticed that you didn’t specify the standard outdoor temperature. For my statement, it should be between -10°C and -12°C (14°F and 10°F). Otherwise, it would need to be reconsidered.
hegi___ schrieb:
With your KFW40 standard and the reference outdoor temperature, you can easily achieve an annual performance factor between 4.55 and 4.60 with an air-to-water heat pump at 30°C (86°F) supply temperature. Unfortunately, that is a misconception.
In such cases, the proportion of domestic hot water demand is significantly higher compared to a house built to the energy saving ordinance standard, for example.
As a result, the annual performance factor is lower.
Check out Elbehaus; they built us a good, affordable KfW 40 house in the suburban area, and you can arrange the plus package yourself… Ytong blocks plus insulation.
Visit some building trade fairs and show villages—there’s a large one in Werder, for example. Get price quotes from Town & Country and from Scanhaus Marlow. Then take a look at the federal state construction loans (BLBs).
This will give you a better idea of the options. Committing to a specific type of brick and heating system this early doesn’t make much sense.
Visit some building trade fairs and show villages—there’s a large one in Werder, for example. Get price quotes from Town & Country and from Scanhaus Marlow. Then take a look at the federal state construction loans (BLBs).
This will give you a better idea of the options. Committing to a specific type of brick and heating system this early doesn’t make much sense.
@hegi___
You can also overdo it..
There are several options for geothermal installation (estimated costs!):
And @PeterS90 has not explicitly ruled out any so far
However, there are also:
Regarding the annual costs (under 2.), I made a rough estimate:
Energy use in the first years (due to moisture in the house, etc.) is usually somewhat higher, so the savings from geothermal energy could be slightly greater.
The initial investment costs should balance out roughly, although the ground-source heat pump will likely cost €1,000–2,000 more.
This results in additional or reduced costs for the ground-source heat pump compared to the air-to-water heat pump ranging from €7,500 to -€500 (depending on the geothermal installation method).
If you want to exaggerate, you could also factor in the average device “lifespan” and that the ground loop can still be used if the heating system needs to be replaced—but I leave that aside here.
(Roughly speaking, ground-source heat pumps tend to last longer than air-to-water heat pumps because their components are located indoors, in a dry and temperature-controlled basement or utility room.
This naturally prolongs their lifespan.)
However, exact data for a detailed cost breakdown is missing.
Over a 20-year period, it is probably a break-even situation. (Depending on the geothermal installation method)
You can also overdo it..
There are several options for geothermal installation (estimated costs!):
And @PeterS90 has not explicitly ruled out any so far
- Drilling = €10,000
- Trench collector DIY = €3,000
- Trench collector by company = €7,000
However, there are also:
- Subsidy (BAFA) = €4,500
- Annual cost savings = approx. €120
Regarding the annual costs (under 2.), I made a rough estimate:
- Final energy demand per year for KfW40 = realistically 6,000 kWh
- Air-to-water heat pump (seasonal performance factor 3.5) = 1,714 kWh -> electricity price €0.30 / kWh = €514 per year
- Ground-source heat pump (seasonal performance factor 4.5) = 1,333 kWh -> electricity price €0.30 / kWh = €400 per year
Energy use in the first years (due to moisture in the house, etc.) is usually somewhat higher, so the savings from geothermal energy could be slightly greater.
The initial investment costs should balance out roughly, although the ground-source heat pump will likely cost €1,000–2,000 more.
This results in additional or reduced costs for the ground-source heat pump compared to the air-to-water heat pump ranging from €7,500 to -€500 (depending on the geothermal installation method).
If you want to exaggerate, you could also factor in the average device “lifespan” and that the ground loop can still be used if the heating system needs to be replaced—but I leave that aside here.
(Roughly speaking, ground-source heat pumps tend to last longer than air-to-water heat pumps because their components are located indoors, in a dry and temperature-controlled basement or utility room.
This naturally prolongs their lifespan.)
However, exact data for a detailed cost breakdown is missing.
Over a 20-year period, it is probably a break-even situation. (Depending on the geothermal installation method)
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