ᐅ Gas with solar thermal? Or heat pump with photovoltaic? Advice needed
Created on: 5 Feb 2020 08:57
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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.
T_im_Norden schrieb:
What are your monthly costs with a heat pump?Just under €60 for 160 m² (1,722 ft²) KfW55 standard (insulation meets energy-saving regulation standards except for the window profiles, which have 6 chambers instead of 5). Photovoltaic system not yet considered. But I find such comparisons pointless. A colleague once said he only pays €30 per month, but in his living room it wasn’t even 21°C (70°F), and the rest of the house barely felt heated. Anyone who prefers a warmer indoor temperature simply consumes more energy, even with the same system setup, so you can’t draw conclusions about the technology from that.Nordlys schrieb:
...and don’t forget the contractor invoices for all that technical equipment. Those are costs too.The initial purchase cost was a bit higher for us, but the very good KFW financing conditions made up for that. Afterwards, we paid for one maintenance. From now on, we do it ourselves once a year; for us, it only requires an Allen key, a vacuum cleaner, and a showerhead.T
T_im_Norden6 Feb 2020 12:16It’s clear that it’s not 100% comparable.
My goal was simply to have some figures to refer to.
We currently live in a house of about 120 m2 (1,290 sq ft) built in 1996, and our monthly gas costs are 80 euros.
The house doesn’t even have a condensing boiler.
I assume that in a new build, we will consume significantly less energy.
My goal was simply to have some figures to refer to.
We currently live in a house of about 120 m2 (1,290 sq ft) built in 1996, and our monthly gas costs are 80 euros.
The house doesn’t even have a condensing boiler.
I assume that in a new build, we will consume significantly less energy.
Professionally, I am only used to thinking economically when it comes to real estate. I am not doing any favor to tenants or leaseholders by slapping a lot of polystyrene insulation on the walls just to improve the energy certificate, especially if I install expensive heating technology or even photovoltaic systems. These investments are passed on in the base rent. The maintenance and operating costs then increase the total rent. What you save in one area is easily offset by additional expenses in another. This does not benefit the occupant of the apartment. In the end, they pay more without actually living better.
This is not an isolated case; it applies to rental properties almost always, unless they are so run-down that there is mold, water intrusion, or severe drafts. But we do not allow it to get that far.
What applies here also applies to homeownership. The numbers do not change. That’s why there is a gas boiler, and why it’s required by law, solar thermal systems — which economically don’t really make sense — but nobody in Berlin wants to hear that. K.
This is not an isolated case; it applies to rental properties almost always, unless they are so run-down that there is mold, water intrusion, or severe drafts. But we do not allow it to get that far.
What applies here also applies to homeownership. The numbers do not change. That’s why there is a gas boiler, and why it’s required by law, solar thermal systems — which economically don’t really make sense — but nobody in Berlin wants to hear that. K.
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Micha85897 Feb 2020 10:38Hello,
I realize this is a hot topic.
In the end, I want and need to choose the more economical system, and that decision has to be made now, not in 10 years — since no one has yet developed a reliable crystal ball for looking into the future.
As already mentioned, for me the issue with heat pumps and photovoltaic systems is also a major part of “playing around,” since it’s a new technology that at least appears to offer a future-proof and cost-effective solution. Some might even argue: …then I can charge my electric car with the photovoltaic system… which I think is nonsense because you would need a huge photovoltaic system in northern Germany, where there is little sun.
I have an appointment at the consumer advice center in two weeks and will talk to an independent engineer with a diploma about this topic. Let’s see what they say?! I will definitely report back!
I realize this is a hot topic.
In the end, I want and need to choose the more economical system, and that decision has to be made now, not in 10 years — since no one has yet developed a reliable crystal ball for looking into the future.
As already mentioned, for me the issue with heat pumps and photovoltaic systems is also a major part of “playing around,” since it’s a new technology that at least appears to offer a future-proof and cost-effective solution. Some might even argue: …then I can charge my electric car with the photovoltaic system… which I think is nonsense because you would need a huge photovoltaic system in northern Germany, where there is little sun.
I have an appointment at the consumer advice center in two weeks and will talk to an independent engineer with a diploma about this topic. Let’s see what they say?! I will definitely report back!
Micha8589 schrieb:
For me, the issue with heat pumps and photovoltaic systems is also a big part of the “fun” factor. Not really. You can tinker with a gas boiler just as much as with a heat pump. Let’s be honest, the average end user hardly ever goes beyond adjusting the controls on the device itself, and with both common consumer heat pumps and gas boilers, you have essentially the same options. Granted, gas boilers lack a cooling function, but that’s hardly worth mentioning. Without a shading concept, both systems will retain heat indoors.
Micha8589 schrieb:
Because it’s a new technology that at least appears to offer a future-proof and economical system. That’s not entirely true either. The technology isn’t new; it’s just being promoted more due to political incentives and current topics, which is why it’s so widely discussed. Other countries, for example, rely on pure electric heating and consider that the future.
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