Hello everyone!
A quick question:
Why do people actually add solar thermal systems to their gas heating?
Is it because they have to comply with the energy saving regulations?
Wrong, you are allowed to skip solar thermal if other measures reduce energy consumption by at least 15%.
Example:
I’m planning a KfW-55 house with gas heating, solar thermal, controlled ventilation with heat recovery, and excellent insulation.
Now I remove the solar thermal system. What happens?
I lose the KfW-55 status and end up with KfW-70, so I lose a €2,500 subsidy. But I save €6,000 by not installing solar thermal. The operating costs increase by €50 per year due to the missing solar thermal, which adds up to €1,000 over 20 years. So overall, I still save €2,500.
Savings:
€6,000 saved by not installing solar thermal*
- €2,500 lost KfW-55 subsidy
- €1,000 higher operating costs due to no solar thermal*
=======
€2,500
Sounds like an attractive alternative, or is there a major calculation mistake somewhere?
The whole calculation would also apply to a KfW-85 house, which would qualify as a KfW-100 house without the solar thermal.
Best regards
jx7
PS:
Please don’t bring up heat pumps or pellet heating; this is not meant to start a fundamental debate about gas versus heat pumps (with sharp increases in energy prices, heat pumps will eventually become more cost-effective). The initial question is simply: "If using gas, then maybe without solar thermal?"
* Source: xxx-Heizungsvergleich-de "Gas + 5sqm solar thermal"
A quick question:
Why do people actually add solar thermal systems to their gas heating?
Is it because they have to comply with the energy saving regulations?
Wrong, you are allowed to skip solar thermal if other measures reduce energy consumption by at least 15%.
Example:
I’m planning a KfW-55 house with gas heating, solar thermal, controlled ventilation with heat recovery, and excellent insulation.
Now I remove the solar thermal system. What happens?
I lose the KfW-55 status and end up with KfW-70, so I lose a €2,500 subsidy. But I save €6,000 by not installing solar thermal. The operating costs increase by €50 per year due to the missing solar thermal, which adds up to €1,000 over 20 years. So overall, I still save €2,500.
Savings:
€6,000 saved by not installing solar thermal*
- €2,500 lost KfW-55 subsidy
- €1,000 higher operating costs due to no solar thermal*
=======
€2,500
Sounds like an attractive alternative, or is there a major calculation mistake somewhere?
The whole calculation would also apply to a KfW-85 house, which would qualify as a KfW-100 house without the solar thermal.
Best regards
jx7
PS:
Please don’t bring up heat pumps or pellet heating; this is not meant to start a fundamental debate about gas versus heat pumps (with sharp increases in energy prices, heat pumps will eventually become more cost-effective). The initial question is simply: "If using gas, then maybe without solar thermal?"
* Source: xxx-Heizungsvergleich-de "Gas + 5sqm solar thermal"
B
Bieber081516 Mar 2015 11:30jx7 schrieb:
Sounds like an interesting alternative, or is there a major calculation error somewhere? If you want to calculate accurately, you need to take into account that payments are always made at specific points in time. The conversion is then done using an (assumed or known) interest rate (“discounting,” determining present value, etc.).Mycraft schrieb:
No... it’s actually basic knowledge when building a house... Wow, you’re setting the bar quite high, in my opinion. Where can a layperson find clear information on what is legal and what is not (specifically regarding heating and hot water)? And what is technically feasible or sensible? And where can a layperson get tools and information to then determine what makes financial sense? (These are not rhetorical questions, I’m genuinely interested in the answers).
Everything is covered in the Energy Saving Ordinance and the Renewable Energy Heat Act... and if you don’t understand the text, simply look for resources where someone has explained it in layman’s terms... and there are plenty of those available.
What is technically feasible or reasonable is always a case-by-case decision, because what works for your neighbor might not work for you.
All the necessary tools and resources are right in front of you as you read this response... if you don’t know how to use them, then of course a professional can help... but you should be very cautious because most are not unbiased.
What is technically feasible or reasonable is always a case-by-case decision, because what works for your neighbor might not work for you.
All the necessary tools and resources are right in front of you as you read this response... if you don’t know how to use them, then of course a professional can help... but you should be very cautious because most are not unbiased.
E
ErikErdgas16 Jul 2015 15:54Hello,
of course it is basically possible to build without solar, but you should keep this option open. Open, for example, by installing appropriate empty conduits or selecting a system that allows for future expansion. The fact is that in a few years, the net-zero energy standard will be the benchmark for new construction. This also means that your house competes with other properties (especially in cases of renting or selling, but also for example when using it as collateral for a loan), and the goal should be for your property to perform well in these situations. If I install a solar thermal system, it might not only be to meet legal requirements but to achieve a truly sustainable effect for domestic hot water production and heating support.
The ultimate wisdom does not lie just in the amount of KfW subsidies and energy savings, but also in the impact on the property value.
Best regards, Erik
of course it is basically possible to build without solar, but you should keep this option open. Open, for example, by installing appropriate empty conduits or selecting a system that allows for future expansion. The fact is that in a few years, the net-zero energy standard will be the benchmark for new construction. This also means that your house competes with other properties (especially in cases of renting or selling, but also for example when using it as collateral for a loan), and the goal should be for your property to perform well in these situations. If I install a solar thermal system, it might not only be to meet legal requirements but to achieve a truly sustainable effect for domestic hot water production and heating support.
The ultimate wisdom does not lie just in the amount of KfW subsidies and energy savings, but also in the impact on the property value.
Best regards, Erik
B
Bauexperte16 Jul 2015 22:38ErikErdgas schrieb:
If I install a solar thermal system, it might not only be to meet legal requirements but to achieve a truly sustainable effect for hot water generation and heating support.I fully understand that you represent your industry; however, even you should realize that the above is nonsense. Regards, Bauexperte
V
Vespa Fahrer29 Jul 2015 10:03Mycraft schrieb:
yes, one of them...V
Vespa Fahrer29 Jul 2015 10:18Hello,
we received a KW 70 standard house. Approximately 220m² (2370 sq ft) total area, of which 170m² (1830 sq ft) is living space area including sloped ceilings. Heating is gas with a 300-liter (79 gallon) water storage tank connected to solar thermal panels on the roof (2 panels).
Since May, I have not used any gas. Currently, all hot water production is covered by the panels. During the transition phase, when there was sunlight, the underfloor heating was also supplied by the solar system. Our gas consumption is now about 30 kWh/m². I cannot say what it would be without the solar thermal system.
PS (However, I burned about 3rm (cubic meters) of wood in the fireplace during winter; this energy amount should still be added.)
we received a KW 70 standard house. Approximately 220m² (2370 sq ft) total area, of which 170m² (1830 sq ft) is living space area including sloped ceilings. Heating is gas with a 300-liter (79 gallon) water storage tank connected to solar thermal panels on the roof (2 panels).
Since May, I have not used any gas. Currently, all hot water production is covered by the panels. During the transition phase, when there was sunlight, the underfloor heating was also supplied by the solar system. Our gas consumption is now about 30 kWh/m². I cannot say what it would be without the solar thermal system.
PS (However, I burned about 3rm (cubic meters) of wood in the fireplace during winter; this energy amount should still be added.)
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