ᐅ Is an air-to-water heat pump a practical option for renovating a listed building to meet Efficiency House standards (160% energy savings regulation)?
Created on: 14 Jan 2021 09:11
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RomeoZwo
Hello everyone,
This is about the renovation of a listed single-family house for rental purposes. According to the energy consultant (an architect specializing in renovations), using an air-to-water heat pump is recommended because a gas condensing boiler would require significantly more insulation work (internal insulation of 8cm (3 inches) instead of 4cm (1.5 inches)) and thus reduce the living space. The air-to-water heat pump could be installed in the basement, with air intake and exhaust through the former coal window (basement top edge about 80cm (31 inches) above ground level). Photovoltaic or solar thermal systems are not possible due to heritage protection. Until now, I had assumed a gas boiler for the house since there is a gas connection in the street, although it has not yet been connected to the house (original heating was a central coal heating system, but unused and unoccupied for 30 years).
As a rental property, it is also interesting that the green/red political plans to impose the CO2 tax on landlords would not be problematic in this case, since electricity costs are charged directly to the tenant and therefore initially would not appear in the additional costs.
On paper, the air-to-water heat pump is clearly advantageous, but what is the reality here? In 2017, we chose gas for a new build due to the high electricity consumption. This is an old building that is allowed to have up to 60% more primary energy demand than a new build. Can the figures for the air-to-water heat pump be trusted to some extent, or will the electricity consumption be a disaster?
Thanks in advance for your opinions—I had never really considered an air-to-water heat pump before and therefore haven't looked into it much yet.
This is about the renovation of a listed single-family house for rental purposes. According to the energy consultant (an architect specializing in renovations), using an air-to-water heat pump is recommended because a gas condensing boiler would require significantly more insulation work (internal insulation of 8cm (3 inches) instead of 4cm (1.5 inches)) and thus reduce the living space. The air-to-water heat pump could be installed in the basement, with air intake and exhaust through the former coal window (basement top edge about 80cm (31 inches) above ground level). Photovoltaic or solar thermal systems are not possible due to heritage protection. Until now, I had assumed a gas boiler for the house since there is a gas connection in the street, although it has not yet been connected to the house (original heating was a central coal heating system, but unused and unoccupied for 30 years).
As a rental property, it is also interesting that the green/red political plans to impose the CO2 tax on landlords would not be problematic in this case, since electricity costs are charged directly to the tenant and therefore initially would not appear in the additional costs.
On paper, the air-to-water heat pump is clearly advantageous, but what is the reality here? In 2017, we chose gas for a new build due to the high electricity consumption. This is an old building that is allowed to have up to 60% more primary energy demand than a new build. Can the figures for the air-to-water heat pump be trusted to some extent, or will the electricity consumption be a disaster?
Thanks in advance for your opinions—I had never really considered an air-to-water heat pump before and therefore haven't looked into it much yet.
No. Gas is available in the street. As an alternative to the air-to-water heat pump, a groundwater heat pump would also be possible. This is likely to be approved in the area. With all subsidies included, the investment cost would be roughly comparable to a gas heating system. For me, the advantage remains that I wouldn’t have to deal with the "landlord’s share of the CO2 tax."
Would a groundwater heat pump generally be better? Require less maintenance? Its efficiency at low temperatures seems to be significantly higher.
Would a groundwater heat pump generally be better? Require less maintenance? Its efficiency at low temperatures seems to be significantly higher.
Based on the repair costs mentioned and some of the problem predictions here, I guess I’m lucky to have the only air-to-water heat pump ever built that runs without any issues!? It makes sense, though, since with the gas heating system I had before, the repair service came to my apartment at least once a year because it liked to break down right before holidays. But well, it was replaced after 9 years anyway because the repair costs would have been higher than a replacement.
Yes, the text might contain some sarcasm.
Back on topic: If the original poster prefers gas, maybe have someone calculate whether better insulation than thermal conductivity class 42 (WLG 42) would be possible, so that only 4cm (1.6 inches) of insulation would be needed even with gas?
PS: In its fifth year without a new compressor.
Yes, the text might contain some sarcasm.
Back on topic: If the original poster prefers gas, maybe have someone calculate whether better insulation than thermal conductivity class 42 (WLG 42) would be possible, so that only 4cm (1.6 inches) of insulation would be needed even with gas?
PS: In its fifth year without a new compressor.
Wait a minute. Has our government really become that unreasonable? So, if you have a gas heating system, you have to insulate so much that otherwise it won’t be approved? In the end, you are financially forced to choose the far less efficient and more environmentally harmful air-to-water heat pump?
Germany is destroying itself — this is yet another example of how we are ruining everything...
Germany is destroying itself — this is yet another example of how we are ruining everything...
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nordanney15 Jan 2021 11:21Bookstar schrieb:
Wait a minute. Has our government really gone that crazy? So with a gas heating system, you have to insulate so much that otherwise it won’t get approved? Yep, that's due to the calculation methods. With gas, the house scores "worse."
Bookstar schrieb:
In the end, you’re financially forced to use the much less efficient and more environmentally harmful air-to-water heat pump? Only you could come up with that assessment 😉
What I would do:
- WLG 42 for interior insulation is the worst possible insulation option you can buy for money
==> upgrade to at least WLG 32/35 – costs roughly the same
- Why only 4cm (1.5 inches) of insulation? The extra cost for 8cm (3 inches) is small since only the material cost increases slightly – fixed costs like plastering, labor, etc., remain the same
==> apply 8cm (3 inches) insulation directly (for a house of 10x10m (33x33 ft), we’re talking about losing just over one square meter (11 sq ft) of living space)
- Recalculate with the above insulation measures and then consider the air-to-water heat pump more closely
- Design the underfloor heating with a consistent 7.5cm (3 inches) thickness (or less if necessary/sensible) to enable the lowest possible supply temperature
- Choose an air-to-water heat pump as a monoblock with indoor installation (regardless of brand like Panasonic/Wolf/Viessmann or similar)
==> lower prices than split systems, and Panasonic especially offers excellent performance and high tolerance to misuse/misconfiguration
- Involve an engineering firm for heating system planning/design (cost around 200-300€ for room-by-room heat load calculation plus computational and graphical design of the underfloor heating)
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