ᐅ Which heating system? Air source heat pump / gas / geothermal heating
Created on: 26 Mar 2015 19:57
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Nina132
Hello everyone,
we are building a single-family house with 155m2 (1,670 sq ft) and want to try to meet KfW55 standards (at least that is what is stated in the contract). Underfloor heating is mandatory. We are working with an architect who also acts as the general contractor, so the house will be delivered turnkey.
The challenges are as follows:
1. North-facing slope – no opportunity for solar panels
2. Sloped site – the ground floor (GF) will be partially built into the hillside at the back. The bedrooms will be on the GF, while the living area is on the upper floor (UF) with a level exit “onto” the slope. By embedding the GF on one side, we can have a reasonably flat garden at the top.
3. There are currently just two of us, but a child is planned in about five years
4. We want a large bathtub and will therefore need a lot of hot water
5. I like to ventilate frequently and thoroughly
6. The utility room is on the GF along with the bedrooms. Could there be noise issues?
Now about the heating decision.
Originally, especially my partner wanted a ground source heat pump. That is probably the best option in terms of quality and ecology, but it is very expensive.
An air source heat pump is of course an alternative, but I’m concerned about electricity costs in winter because I suspect that, especially the GF, will cool down quickly due to the hillside situation.
Our architect recommends a gas condensing boiler, saying this is standard for 80% of new builds. We actually wanted to move away from gas and oil, but electricity also involves fossil fuels – at least indirectly. Of course, this would probably rule out KfW55 compliance, but I think KfW70 would also be acceptable.
What are your thoughts?
we are building a single-family house with 155m2 (1,670 sq ft) and want to try to meet KfW55 standards (at least that is what is stated in the contract). Underfloor heating is mandatory. We are working with an architect who also acts as the general contractor, so the house will be delivered turnkey.
The challenges are as follows:
1. North-facing slope – no opportunity for solar panels
2. Sloped site – the ground floor (GF) will be partially built into the hillside at the back. The bedrooms will be on the GF, while the living area is on the upper floor (UF) with a level exit “onto” the slope. By embedding the GF on one side, we can have a reasonably flat garden at the top.
3. There are currently just two of us, but a child is planned in about five years
4. We want a large bathtub and will therefore need a lot of hot water
5. I like to ventilate frequently and thoroughly
6. The utility room is on the GF along with the bedrooms. Could there be noise issues?
Now about the heating decision.
Originally, especially my partner wanted a ground source heat pump. That is probably the best option in terms of quality and ecology, but it is very expensive.
An air source heat pump is of course an alternative, but I’m concerned about electricity costs in winter because I suspect that, especially the GF, will cool down quickly due to the hillside situation.
Our architect recommends a gas condensing boiler, saying this is standard for 80% of new builds. We actually wanted to move away from gas and oil, but electricity also involves fossil fuels – at least indirectly. Of course, this would probably rule out KfW55 compliance, but I think KfW70 would also be acceptable.
What are your thoughts?
D
derstefanm31 Mar 2015 22:13Heat pumps are supposed to be much more expensive than a gas condensing boiler with solar panels.
Maybe something will come up starting tomorrow, since from April 1st the BAFA subsidy for heat pumps is set to take effect, which also provides a €4000 (approximately $4300) grant for new buildings. In that case, I would reconsider the whole thing.
Maybe something will come up starting tomorrow, since from April 1st the BAFA subsidy for heat pumps is set to take effect, which also provides a €4000 (approximately $4300) grant for new buildings. In that case, I would reconsider the whole thing.
The new BAFA funding for new buildings is only an innovation grant; it is not a general subsidy for heat pumps. For this, a seasonal performance factor (SPF) of at least 4.5 is required, which not all systems can achieve.
If this requirement is met, the innovation grant is awarded at the amount of the base funding, which is 4,500 euros.
@Bieber0815
In addition to the Energy Saving Ordinance (EnEV), you must also comply with the Renewable Energies Heat Act (EEWärmeG). Simply put, this law requires that at least 15% of your energy must come from renewable sources. The minimum option is solar thermal systems installed on the roof.
However, if you reduce energy demand by 15% compared to the Energy Saving Ordinance’s requirements for primary energy and the building envelope (for example, through extra insulation, better windows, etc.), then solar thermal and similar systems may no longer be necessary.
If this requirement is met, the innovation grant is awarded at the amount of the base funding, which is 4,500 euros.
@Bieber0815
In addition to the Energy Saving Ordinance (EnEV), you must also comply with the Renewable Energies Heat Act (EEWärmeG). Simply put, this law requires that at least 15% of your energy must come from renewable sources. The minimum option is solar thermal systems installed on the roof.
However, if you reduce energy demand by 15% compared to the Energy Saving Ordinance’s requirements for primary energy and the building envelope (for example, through extra insulation, better windows, etc.), then solar thermal and similar systems may no longer be necessary.
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Bieber08151 Apr 2015 09:54Lars881 schrieb:
In addition to the Energy Saving Ordinance, you also need to comply with the Renewable Energy Heat Act. Simply put, this means you must cover at least 15% of your energy demand with renewable sources. At the very least, this could be solar thermal systems installed on the roof.
However, if you reduce the primary energy demand and improve the building envelope by at least 15% compared to the Energy Saving Ordinance requirements (for example, through better insulation, higher-quality windows, etc.), then solar systems and similar renewable technologies may no longer be mandatory. So, that means either a house with 100% of the primary energy demand, of which at least 15% comes from renewable sources, or a house with a maximum of 85% primary energy demand, which can be fully covered by fossil energy. Is that correct?
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Bauexperte1 Apr 2015 10:06Hello,
Basically, it can be assumed that if the primary energy demand is reduced by 5% and the building envelope is improved by at least 15%, solar panels on the roof can be omitted. Walls, ceiling/roof, floors, and windows need to be better insulated. How to best implement the 15% rule must be calculated individually for each specific building.
Best regards, Bauexperte
Bieber0815 schrieb:
Could you briefly explain this rule?
Basically, it can be assumed that if the primary energy demand is reduced by 5% and the building envelope is improved by at least 15%, solar panels on the roof can be omitted. Walls, ceiling/roof, floors, and windows need to be better insulated. How to best implement the 15% rule must be calculated individually for each specific building.
Best regards, Bauexperte
B
Bieber08151 Apr 2015 10:47Lars881 schrieb:
Correct, but also 15% for the building envelope.I don’t understand the second part of the sentence :-(. Is it meant as "in addition"? Isn’t it enough to reduce the primary energy demand to 85%? What else should be done to the building envelope? Or do you just mean that the improvements to the building envelope are what reduce the primary energy demand to 85%?Bauexperte schrieb:
Basically, it can be assumed that with a 5% reduction in primary energy demand and at the same time at least a 15% better building envelopeNow I’m confused again. What exactly is a better building envelope? How is "better" assessed if not by the primary energy demand of the house? In other words: measures to reduce heat loss (for example through the envelope) reduce the primary energy demand to 85%: done, the builder is allowed to install a gas condensing boiler without heat pump, without solar thermal, without photovoltaic.