ᐅ As for the planning and design of the energy standard and heating concept, beforehand
Created on: 25 Apr 2019 15:55
Q
quattro123
Hello everyone,
For days (or rather weeks) now, I have been researching the topic of house construction.
First of all, it will be a semi-detached house, and a friend who is an architect is designing it. He will handle all the necessary tasks to submit the plans. Heating concepts, ventilation concepts, etc., are not included here.
The plot is on a slight slope, which is why we are planning a 50 m² (540 sq ft) ground-level granny flat, and the area behind the flat, which connects to the earth, will be used as a basement for heating systems, etc.
Overall, the house will have about 250 m² (2,700 sq ft) of gross floor area and a roof pitch of 45 degrees.
I have already read a lot here in the forum, which has been very helpful, but I think that for the topic of house building, each issue requires its own discussion. 😉
My questions are surely the classic ones:
This is very important to me because I am desperately trying to find the best energy concept for my project and do not know the best way to proceed. For me, the standard according to the 2016 Energy Saving Ordinance is already decent. Maybe one can just save all the effort and simply build with a gas condensing boiler?
Best regards!
For days (or rather weeks) now, I have been researching the topic of house construction.
First of all, it will be a semi-detached house, and a friend who is an architect is designing it. He will handle all the necessary tasks to submit the plans. Heating concepts, ventilation concepts, etc., are not included here.
The plot is on a slight slope, which is why we are planning a 50 m² (540 sq ft) ground-level granny flat, and the area behind the flat, which connects to the earth, will be used as a basement for heating systems, etc.
Overall, the house will have about 250 m² (2,700 sq ft) of gross floor area and a roof pitch of 45 degrees.
I have already read a lot here in the forum, which has been very helpful, but I think that for the topic of house building, each issue requires its own discussion. 😉
My questions are surely the classic ones:
- Building a house according to the 2016 Energy Saving Ordinance or aiming for KfW 55 standard? I am currently unsure whether the house will be built according to the 2016 Energy Saving Ordinance or to KfW 55 standard.
- Ventilation system From when is a mechanical ventilation system actually mandatory?
- KfW subsidies I do not intend to take out a KfW loan. Can I still apply for individual KfW subsidies? Can I apply for individual subsidies myself, or does every subsidy have to be obtained through the bank?
- How to heat? I want to design my heating system primarily for economic efficiency. Being as green or self-sufficient as possible is generally not the top priority. It should simply be the “most economical” system from today’s perspective, with a 15-year outlook (assuming current prices for all necessary resources). A gas connection has already been installed up to the plot. Currently, the new development area is promoting fuel cells (up to €10,000 subsidy). Are there any experiences with this? The system sounds great in theory, with high efficiency, etc.
Ultimately, this is a question of economic efficiency. But how can I find out exactly?
Do I take my plans to an energy consultant who then calculates this for me?
What costs can be expected for such an energy consultant’s assessment?
I am currently planning to build with Poroton T9 36.5 blocks. As far as I know, it is difficult to achieve KfW 55 with these blocks since the U-value is around 0.23 W/(m²K)?
As far as I know, all subsidies must be applied for before starting construction. So, building first and then applying is not possible, right?
After much reading here in the forum, I have come to the conclusion that an air source heat pump combined with a small photovoltaic system is currently probably the most economical option?
This is very important to me because I am desperately trying to find the best energy concept for my project and do not know the best way to proceed. For me, the standard according to the 2016 Energy Saving Ordinance is already decent. Maybe one can just save all the effort and simply build with a gas condensing boiler?
Best regards!
Q
quattro12326 Apr 2019 09:59Hello, first of all, thank you for all the input. I will address different points later on.
But first, I have a question regarding the recommended thread that includes an example calculation of various heating systems: https://www.hausbau-forum.de/threads/gas-oder-Wärmepumpe-erfahrungen-feedback.30849/page-5#post-320160
According to that, the air-to-water heat pump would be significantly more attractive than the gas heating system. However, the calculation does not seem to be entirely realistic when it comes to electricity costs. Could someone clarify this in more detail? Where is the mistake, or how “neutral” is this calculation at all?
At least I had the impression that I would be much better off with an air-to-water heat pump than with gas. However, the majority of opinions here in the forum tend to favor gas.
Best regards 🙂
But first, I have a question regarding the recommended thread that includes an example calculation of various heating systems: https://www.hausbau-forum.de/threads/gas-oder-Wärmepumpe-erfahrungen-feedback.30849/page-5#post-320160
According to that, the air-to-water heat pump would be significantly more attractive than the gas heating system. However, the calculation does not seem to be entirely realistic when it comes to electricity costs. Could someone clarify this in more detail? Where is the mistake, or how “neutral” is this calculation at all?
At least I had the impression that I would be much better off with an air-to-water heat pump than with gas. However, the majority of opinions here in the forum tend to favor gas.
Best regards 🙂
Q
quattro12326 Apr 2019 10:30Snowy36 schrieb:
Is it still possible to get KfW funding twice for two residential units (a granny flat plus a main unit) under current regulations?
If so, you should double-check that... We did it, but not for the "great" conditions, rather to stay flexible... with us, there were unlimited options for special repayments and the loan ends after just 10 years, which then significantly reduces our monthly payments.
Think carefully about using a 36.5 (°C (98°F)) system if you have tenants; you should probably choose some with additional filling! The tenant won’t want to hear the noise you make downstairs... and if you use a filled system, you are almost back at KfW 55. You need to apply for the funding in advance... and watch out for impact sound insulation as well...
Go with gas. See another thread and comment by BoxandProof.
For decentralized ventilation, even for myself, I would only use it in the bathroom for comfort reasons; otherwise, these units are too noisy to keep running constantly in living spaces. But maybe there are better devices nowadays. Yes, there are still subsidies for multiple residential units.
A general question about ventilation: From when is it actually mandatory, and how is it monitored? Or is it more of an unwritten rule that you should do it because it simply makes sense due to the airtightness of the building?
I’m missing a clear, hard criterion here.
It is not mandatory, but you should not build without some form of mechanical ventilation, whether for rental or personal use. Modern houses are too airtight. This is unhealthy and quickly leads to mold forming in corners. The cheapest option is trickle vents installed in window frames.
B
boxandroof26 Apr 2019 13:01quattro123 schrieb:
But first, a question about the recommended topic that includes example calculations for different heating systems. You need to calculate that yourself for your housing units and based on your own quotes. The example is just that—an example without a source. Our situation was completely different. Also, every so-called expert will tell you something different, so it’s best to inform yourself, do the math, or just choose gas and stop worrying about it. You will also need the right skilled tradespeople for everything, which was our biggest challenge in installing the affordable heat pump. But it was worth it.
Here’s what I would do:
Apartment: Separate gas heating, hot water without storage tank. Decentralized/simple ventilation with or without heat recovery.
And for your housing unit either
a) simple: gas, but possibly shared with the apartment.
or:
b) well-planned heat pump with 1. trench collector installed by yourself + subsidy, or 2. a simple and inexpensive Japanese air-to-water heat pump without an indoor unit (not a split system).
Ventilation for your housing unit is optional and purely for comfort. Central ventilation with heat recovery is the optimum. Avoid solar thermal if possible, but definitely install photovoltaics.
The funding options for both units were a good tip; KFW has become somewhat more attractive again.
Q
quattro12326 Apr 2019 20:18And how does the process with KFW funding work? I assume that many decisions will be made during construction and on short notice. Is it still possible to apply for funding at short notice, or do I have to apply for everything well in advance?
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