ᐅ Gas with solar thermal? Or heat pump with photovoltaic? Advice needed
Created on: 5 Feb 2020 08:57
M
Micha8589
Good morning to the forum,
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
I have been researching heating options for quite some time and have gathered a few opinions, which have only made me more uncertain about my decision. That’s why I thought I’d ask the forum.
My family (2 adults, 1 child) is planning to build the following single-family house at the end of this year or beginning of next year:
Single-family home with pitched roof
Approximately 115 m² (1,237 sq ft)
Solid construction (calcium silicate brick ground and upper floors, brick-clad)
No KFW standard
Building location: southern Mecklenburg
Unfortunately, I can’t provide an energy performance certificate or heating load calculation yet, as the preliminary offer is still being prepared. I am also aware that a general statement can’t really be made since every house and heating behavior is individual.
The construction company advised us to install a modern hybrid heating system consisting of a gas condensing boiler and two solar thermal panels on the roof for domestic hot water, as the initial costs are relatively low (plus installation of the central gas connection), and this technology has proven reliable. The entire house is planned to have underfloor heating. According to the company, they have had very positive experiences with this and consider the technology future-proof. (There is also the idea of a fireplace in the living room.)
On the other hand, I think gas prices will not get any cheaper in the future, and the topic of CO₂ taxes (especially concerning the fireplace) worries me somewhat.
In theory, I would prefer to install a geothermal heat pump combined with a suitable photovoltaic system because this would make me independent of fossil fuels and allow me to heat “off-grid” to a certain extent, depending on efficiency. However, I am hesitant because of the very high initial costs and don’t really know how these compare to operational costs. I also can no longer realistically assess which technology offers the best cost-performance ratio (except for air-source heat pumps).
As you can see, I am completely undecided and hope to get some feedback and expertise from the forum.
Thanks in advance for your replies.
M
Micha858919 Feb 2020 12:27Hello everyone,
unfortunately, my energy consultation appointment scheduled for tomorrow will not take place due to personal reasons, so I won’t be able to share any feedback. However, based on all the comments I’ve read in this thread, a preliminary offer that has now been prepared, and discussions with two colleagues who are already building and facing the same issue, I have to admit—which even surprises me—that I am likely to lean towards gas condensing technology combined with solar thermal systems, with the option to upgrade in the future with a photovoltaic system or a ground source heat pump.
unfortunately, my energy consultation appointment scheduled for tomorrow will not take place due to personal reasons, so I won’t be able to share any feedback. However, based on all the comments I’ve read in this thread, a preliminary offer that has now been prepared, and discussions with two colleagues who are already building and facing the same issue, I have to admit—which even surprises me—that I am likely to lean towards gas condensing technology combined with solar thermal systems, with the option to upgrade in the future with a photovoltaic system or a ground source heat pump.
I’ve lost track in this whole thread whether you have planned a mechanical ventilation system with heat recovery. If so, I would skip the solar thermal system. It’s basically no longer necessary if executed correctly.
Is it possible to retrofit something like a ground-source heat pump that easily? How airtight does a borehole near the house need to be?
Is it possible to retrofit something like a ground-source heat pump that easily? How airtight does a borehole near the house need to be?
B
blubbernase18 Apr 2020 12:04Very interesting discussion, thank you! (Although I did smile a bit at the complicated description of a split air conditioner) since I am still at the very beginning of my planning and research. One question that arises for me within this discussion is: to what extent does the decision I make today affect my modernization options in the future? If I want to upgrade the heating system in 15 or 20 years, will choosing between today's options limit me later? Or does it not matter?
blubbernase schrieb:
Even though I had to smile a bit at the complicated description of a split air conditioner Yes, that was actually the point alongside raising awareness. Because that’s exactly what general contractors, construction companies, and other home builders do—describe the technology to potential customers in the most complicated way possible and present it as the ultimate solution.
In fact, every heat pump is basically a split air conditioner; they even sell them that way and it’s often indicated directly on the unit. It’s also amusing to see how heat pump buyers then strongly reject split air conditioners as if their lives depended on it, saying things like: “That will never come into my house!” “I’m all for environmental protection.” Yet they are heating with a split system too, it’s just that usually water is heated instead of the air directly.
At least it’s starting to become clear in people’s minds that an air-to-air heat pump is essentially a genuine split air conditioning system and is suboptimal for heating houses in our climate zones.
K
knalltüte20 Apr 2020 22:52May I share the reasons why we are planning a KfW40+ house with a ground-source heat pump, underfloor heating, controlled ventilation, photovoltaic system, and battery storage?
“Of course,” ecology is an important factor. I hope building this way is sustainable. Using a lot of wood instead of concrete or stone (the production of cement releases huge amounts of CO2).
Children and grandchildren — a sense of responsibility.
Still, we have to consider the financial aspect. Funds are available, but unfortunately not unlimited :-/
With extras like controlled ventilation, the indoor climate should hopefully be more pleasant than in a traditional masonry building without controlled ventilation. I do not have personal experience with all alternative building methods, only secondhand information.
A better insulated building will naturally be more expensive, but right now KfW40+ construction is well supported by subsidies, including Progress NRW and BAFA. (By the way, achieving KfW40+ in solid masonry construction is hardly possible with reasonable wall thicknesses.)
My bet: In the medium term, in 10 to 15, at most 20 years, total costs (construction plus operation) will be lower than with “conventional” building.
Fossil fuels are finite; their long-term use will lead to rising costs. A heat pump combined with photovoltaic (as much solar as possible!) and battery storage enables maximum self-consumption of generated electricity. Ideally, a battery electric vehicle would be added in the medium term…
This results in low operating costs over the long term (the photovoltaic system practically pays for itself — if anyone doubts this, just run the numbers with photovoltaic SOL).
However, with any technology, no one can be certain what the future holds regarding efficiency improvements or setbacks (looking into a crystal ball).
And finding the right partner to plan and build this may be challenging…
Also, I cannot and will not recommend any specific way to build. This is intended only as encouragement to consider other options. It can’t hurt — can it?
“Of course,” ecology is an important factor. I hope building this way is sustainable. Using a lot of wood instead of concrete or stone (the production of cement releases huge amounts of CO2).
Children and grandchildren — a sense of responsibility.
Still, we have to consider the financial aspect. Funds are available, but unfortunately not unlimited :-/
With extras like controlled ventilation, the indoor climate should hopefully be more pleasant than in a traditional masonry building without controlled ventilation. I do not have personal experience with all alternative building methods, only secondhand information.
A better insulated building will naturally be more expensive, but right now KfW40+ construction is well supported by subsidies, including Progress NRW and BAFA. (By the way, achieving KfW40+ in solid masonry construction is hardly possible with reasonable wall thicknesses.)
My bet: In the medium term, in 10 to 15, at most 20 years, total costs (construction plus operation) will be lower than with “conventional” building.
Fossil fuels are finite; their long-term use will lead to rising costs. A heat pump combined with photovoltaic (as much solar as possible!) and battery storage enables maximum self-consumption of generated electricity. Ideally, a battery electric vehicle would be added in the medium term…
This results in low operating costs over the long term (the photovoltaic system practically pays for itself — if anyone doubts this, just run the numbers with photovoltaic SOL).
However, with any technology, no one can be certain what the future holds regarding efficiency improvements or setbacks (looking into a crystal ball).
And finding the right partner to plan and build this may be challenging…
Also, I cannot and will not recommend any specific way to build. This is intended only as encouragement to consider other options. It can’t hurt — can it?
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