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NilsHolgerson3 Sep 2020 14:16Good day dear community,
I have bought a house built in 1914 and am planning a renovation. The plan is to replace all the windows. Currently, almost all windows are single-glazed with wooden frames. The new windows will be double-glazed with a U-value of 0.91. The attic will be fully converted. For this, the roof will be insulated with 24 cm (9.5 inches) of rafter insulation. The building envelope is currently uninsulated.
So far, I have only spoken with one heating specialist. He suggested I choose a pellet heating system because a heat pump would not be suitable for my house. The reasons given were:
# Not enough insulation, resulting in too high supply temperatures.
# Therefore, not economically efficient enough.
I actually like the idea of a pellet heating system because I view wood as a positive raw material, and the operating costs are supposed to be lower than those of an oil heating system, according to calculations. Additionally, I could receive a 45% subsidy through BAFA.
However, on this forum, I have come across several posts that clearly advise against pellet heating. The reasons cited are:
# All renovation projects on older buildings are now switching to pellet heating, which drives pellet prices up.
# Pellet heating systems are very prone to faults and therefore expensive to service and repair.
# Removing the ash is a hassle.
# Heat pumps are the technology of the future, and pellet heating is doomed.
This has made me doubt, hence this post. Can anyone help me with this decision? Are the reasons against pellet heating valid, or what do you think?
Facts:
Year built: 1914
Detached single-family house
According to the energy certificate:
Final energy demand 298 kWh/(m²a) (kWh per square meter per year)
Primary energy demand actual value 332 kWh/(m²a), required value 118 kWh/(m²a)
Energy performance of the building envelope: actual value 1.26 W/(m²K), required value 0.56 W/(m²K)
Heating type: low-temperature oil boiler from 1986 (tanks on ground floor (7.73 m² (83 sq ft)), burner in the basement (10.5 m² (113 sq ft)))
Living area: 105 m² (1,130 sq ft), with attic conversion approx. 190 m² (2,045 sq ft)
No gas connection available.
District heating could be installed for 2,500 €.
Space for pellet storage is available where the oil heating tanks are currently located.
If you need more information, feel free to ask.
Thank you in advance for your tips, information, and thoughts!
I have bought a house built in 1914 and am planning a renovation. The plan is to replace all the windows. Currently, almost all windows are single-glazed with wooden frames. The new windows will be double-glazed with a U-value of 0.91. The attic will be fully converted. For this, the roof will be insulated with 24 cm (9.5 inches) of rafter insulation. The building envelope is currently uninsulated.
So far, I have only spoken with one heating specialist. He suggested I choose a pellet heating system because a heat pump would not be suitable for my house. The reasons given were:
# Not enough insulation, resulting in too high supply temperatures.
# Therefore, not economically efficient enough.
I actually like the idea of a pellet heating system because I view wood as a positive raw material, and the operating costs are supposed to be lower than those of an oil heating system, according to calculations. Additionally, I could receive a 45% subsidy through BAFA.
However, on this forum, I have come across several posts that clearly advise against pellet heating. The reasons cited are:
# All renovation projects on older buildings are now switching to pellet heating, which drives pellet prices up.
# Pellet heating systems are very prone to faults and therefore expensive to service and repair.
# Removing the ash is a hassle.
# Heat pumps are the technology of the future, and pellet heating is doomed.
This has made me doubt, hence this post. Can anyone help me with this decision? Are the reasons against pellet heating valid, or what do you think?
Facts:
Year built: 1914
Detached single-family house
According to the energy certificate:
Final energy demand 298 kWh/(m²a) (kWh per square meter per year)
Primary energy demand actual value 332 kWh/(m²a), required value 118 kWh/(m²a)
Energy performance of the building envelope: actual value 1.26 W/(m²K), required value 0.56 W/(m²K)
Heating type: low-temperature oil boiler from 1986 (tanks on ground floor (7.73 m² (83 sq ft)), burner in the basement (10.5 m² (113 sq ft)))
Living area: 105 m² (1,130 sq ft), with attic conversion approx. 190 m² (2,045 sq ft)
No gas connection available.
District heating could be installed for 2,500 €.
Space for pellet storage is available where the oil heating tanks are currently located.
If you need more information, feel free to ask.
Thank you in advance for your tips, information, and thoughts!
When replacing windows in older buildings, it is usually necessary to insulate the exterior wall.
For example: the old window has a U-value (overall) of 2.5 W/m²K, and the uninsulated wall has a U-value of 1.7 W/m²K, so the ratio is correct—the window has the poorer value, as is generally expected.
However, if a new-generation window (0.9 W/m²K or better) is installed without insulating the wall, the wall will become damp and start to develop mold. Obviously, this happens because the window suddenly performs better than the wall.
Ideally, you would insulate the facade, the top floor ceiling, and the basement ceiling. Then you could also install a heat pump. All of this is usually eligible for significant subsidies! Alternatively, you would have to ventilate so much and so often that eventually you would wish for the old single-glazed windows again....
For example: the old window has a U-value (overall) of 2.5 W/m²K, and the uninsulated wall has a U-value of 1.7 W/m²K, so the ratio is correct—the window has the poorer value, as is generally expected.
However, if a new-generation window (0.9 W/m²K or better) is installed without insulating the wall, the wall will become damp and start to develop mold. Obviously, this happens because the window suddenly performs better than the wall.
Ideally, you would insulate the facade, the top floor ceiling, and the basement ceiling. Then you could also install a heat pump. All of this is usually eligible for significant subsidies! Alternatively, you would have to ventilate so much and so often that eventually you would wish for the old single-glazed windows again....
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nordanney3 Sep 2020 14:30To be honest, I find the option of district heating very appealing. This way, you are not tied to a specific heat generator and can switch later if needed. Maybe in a few years, you might consider insulating the building envelope and switching to a heat pump.
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NilsHolgerson3 Sep 2020 16:37So far, everyone has advised me against district heating because the price is too high. Personally, I would just like to take advantage of the really good subsidies available for pellet heating or heat pumps.
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NilsHolgerson3 Sep 2020 16:59I just checked the current prices for district heating in my area. The cost per kWh is 9.551 cents. Online, pellet prices are estimated at 5.9 cents per kWh. That is quite a significant difference.
I would also avoid district heating, as you depend on a single provider who sets the prices. You cannot switch providers. As mentioned above, just replacing the windows can be risky. Have you already talked to an energy consultant? They can assist you, and through them, in addition to BAFA, you may also be able to access KfW funding.