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
Bauexperte24 Nov 2015 13:41sirhc schrieb:
Okay – in our case, it appears that the site plan does not have to be prepared by a surveyor or is already available. Take a look here:§ 3 Building Inspection Ordinance
Site Plan
[...]
(3) The site plan (paragraph 1) and the calculations according to paragraph 2 must be prepared by a cadastral office or by a publicly appointed surveyor and authenticated with official certification (official site plan) if
1. the boundaries of the building plot are not established boundaries within the meaning of § 19 paragraph 1 VermKatG,
2. the boundaries of the building plot and the existing structures on the plot and adjacent plots are surveyed in such a way that coordinates for the boundary points cannot be determined within a unified system, or
3. boundary encroachments exist on the building plot or from adjacent plots,
4. a building encumbrance (Baulast) within the meaning of § 18 rests on the building plot or on adjacent plots.
If there are special property circumstances, especially due to unclear boundary lines of the building plot caused by boundary protrusions or bends, and the requirements for preparing an official site plan according to sentence 1 are not met, the site plan according to paragraph 1 and the calculations according to paragraph 2 can also be prepared by a surveyor who is a member of an engineering chamber; membership in an engineering chamber must be proven upon request by the building authority. In all other cases, these construction documents may also be prepared by the designer.
Are you sure your structural engineer is authorized to prepare the preliminary site plan?
Regards, Bauexperte
D
DerBjoern24 Nov 2015 13:44Then we can only hope that the site plan is in the correct scale and not too old.
Edit: and see Bauexperte's post
Edit: and see Bauexperte's post
N
nordanney24 Nov 2015 14:20The problem is usually that the architect is allowed to create the site plan but doesn’t dare to do it. It was the same in our building area. Almost all architects referred the homeowner to a surveyor (who, of course, wanted to be paid and also took their time), especially the prefabricated house manufacturers.
It makes you wonder why they (the architects) study for so many years if they can’t even produce the site plan—despite having all the necessary information.
It makes you wonder why they (the architects) study for so many years if they can’t even produce the site plan—despite having all the necessary information.
So the site plan is prepared by the structural engineer; we reviewed the passages cited by Bauexperte two weeks ago, and he concluded that these are established boundaries with clear boundary points, or generally speaking, that the conditions are met so that the site plan does not necessarily have to be created by a surveyor. Since he has already prepared and (successfully) submitted several site plans himself, I believe he knows what he is doing. We also know that this is handled differently from district to district.
Bauexperte schrieb:
Yes. But let go of the idea that you can still submit the building permit application this year; that’s simply not going to happen.
The KfW only requires the proof in the front section of form 153 and, after completion of the construction work, confirmation that KfW 70 was actually achieved.I would like to revisit this topic, since it was actually possible to submit the building permit application before the end of the year.
I want to make sure I understand the following correctly:
- Waiving solar thermal systems is possible if the minimum requirements of the energy-saving ordinance are undercut by 15%
- This is equivalent to requiring a KfW 70 certification, meaning an actual reduction of 30%, since there is no standard "KfW 85" — is that correct?
I am currently trying to compare the costs of just meeting the minimum energy-saving ordinance requirements plus solar thermal systems versus undercutting the energy-saving ordinance minimum requirements without solar thermal. The latter saves the costs of the solar thermal system but means additional costs for ETICS and certification, as far as I can see. I have prices for solar thermal and KfW 70 certification, but I’m still missing prices for ETICS.
Thanks and best regards
Hello sirhc,
The Energy Saving Ordinance and KfW are two quite different things. The proof of compliance with the Energy Saving Ordinance is important for the building permit (planning permission), while the KfW certificate is required for subsidized financing through the KfW bank.
To meet the Energy Saving Ordinance requirements, either renewable energies must be used (solar thermal providing more than 15% of heating energy, biomass more than 50%, or heat pumps more than 50%) or the two key values—annual primary energy demand and transmission heat loss—must each be no more than 85% of the Energy Saving Ordinance limit.
For KfW 70, the annual primary energy demand must be at most 70% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 85%.
For KfW 55, the annual primary energy demand must be at most 55% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 70%.
For KfW 40, the annual primary energy demand must be at most 40% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 55%.
These are all figures related to the Energy Saving Ordinance 2009, which still applies to you.
I’m curious about what your price comparison showed. I would strongly guess that without solar thermal, the upfront costs are so much lower that the lower energy consumption costs of a solar thermal solution wouldn’t be enough to offset the additional investment over the first 20 years.
But well, the Energy Saving Ordinance 2009 is now outdated. I’m not familiar with the new regulations, but I assume that with a gas heating system, it probably no longer works without solar thermal.
Best regards
jx7
The Energy Saving Ordinance and KfW are two quite different things. The proof of compliance with the Energy Saving Ordinance is important for the building permit (planning permission), while the KfW certificate is required for subsidized financing through the KfW bank.
To meet the Energy Saving Ordinance requirements, either renewable energies must be used (solar thermal providing more than 15% of heating energy, biomass more than 50%, or heat pumps more than 50%) or the two key values—annual primary energy demand and transmission heat loss—must each be no more than 85% of the Energy Saving Ordinance limit.
For KfW 70, the annual primary energy demand must be at most 70% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 85%.
For KfW 55, the annual primary energy demand must be at most 55% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 70%.
For KfW 40, the annual primary energy demand must be at most 40% of the Energy Saving Ordinance requirement, and the transmission heat loss must be at most 55%.
These are all figures related to the Energy Saving Ordinance 2009, which still applies to you.
I’m curious about what your price comparison showed. I would strongly guess that without solar thermal, the upfront costs are so much lower that the lower energy consumption costs of a solar thermal solution wouldn’t be enough to offset the additional investment over the first 20 years.
But well, the Energy Saving Ordinance 2009 is now outdated. I’m not familiar with the new regulations, but I assume that with a gas heating system, it probably no longer works without solar thermal.
Best regards
jx7
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