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?
130 € without household electricity for new buildings that have been undersized is not so unlikely – there have also been reports of worst-case scenarios consuming 4500 to 6000 kWh (topic Nibe and Viebrockhaus). However, this is likely to improve. No one is saying that gas is bad, right? Even from an ecological perspective, the BUND states that heat pumps with a seasonal performance factor below 3 are not really environmentally friendly (this may have changed somewhat due to shifts in the electricity mix).
If you choose a well-designed ground source heat pump with a seasonal performance factor of 5, and the €5,000 (about $5,500) subsidy from BAFA (new for new builds) also applies, then these systems are no longer so uneconomical...
The heating demand of your house is relatively independent of the number of occupants, as it mainly concerns the building’s heat transmission losses (plus ventilation). A general allowance is then added per person for hot water demand, which is less significant.
If you choose a well-designed ground source heat pump with a seasonal performance factor of 5, and the €5,000 (about $5,500) subsidy from BAFA (new for new builds) also applies, then these systems are no longer so uneconomical...
The heating demand of your house is relatively independent of the number of occupants, as it mainly concerns the building’s heat transmission losses (plus ventilation). A general allowance is then added per person for hot water demand, which is less significant.
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Bauexperte30 Mar 2015 11:04Hello,
Some time ago, I tried to dive deeper into this topic, which is not so simple. What I take away from it is that if an end consumer, for example, is not directly connected to the wind turbine (i.e., without intermediaries), they always receive "grey" electricity; the grid does not differentiate but only transports. Only the additional cost per kWh must be mandatorily invested in expanding renewable energy sources to create pressure on the electricity-producing industry.
That’s why I smile a bit, regardless of the fact that I think it’s good that companies like RWE and others have to rethink.
Best regards, Bauexperte
mcarstensen schrieb:That’s what I assume as well.
Oh, and regarding the "green" electricity. I obviously have to rely on the "certificates."
Some time ago, I tried to dive deeper into this topic, which is not so simple. What I take away from it is that if an end consumer, for example, is not directly connected to the wind turbine (i.e., without intermediaries), they always receive "grey" electricity; the grid does not differentiate but only transports. Only the additional cost per kWh must be mandatorily invested in expanding renewable energy sources to create pressure on the electricity-producing industry.
That’s why I smile a bit, regardless of the fact that I think it’s good that companies like RWE and others have to rethink.
Best regards, Bauexperte
Bauexperte schrieb:
the grid does not differentiate; it only transmits. Only the additional cost per kWh is mandatorily invested in expanding renewable energy, in order to put pressure on the electricity-producing sector.But for us consumers, this is at least a way to support green electricity, or to help expand it better with our few extra cents.
I think that’s fine. But I’m also the kind of person who sorts glass recycling by color, even though it’s supposed to all end up together in the large container later.
I do what I can, since I’m not going to save the world anyway.
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Bauexperte30 Mar 2015 13:03Hello Yvonne,
I responded because, frankly, I’m tired of one-sided viewpoints. Neither can gas be praised uncritically while ignoring the side effects of its extraction, nor can heat pumps be considered the ultimate solution.
Regards, Bauexperte
ypg schrieb:In my opinion, this makes sense …
But at least for us consumers, this is a way to support green electricity and help improve its expansion with our small extra contributions.
I responded because, frankly, I’m tired of one-sided viewpoints. Neither can gas be praised uncritically while ignoring the side effects of its extraction, nor can heat pumps be considered the ultimate solution.
Regards, Bauexperte
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mcarstensen31 Mar 2015 00:12Then I think we pretty much agree. I agree with you that pressure needs to be increased on the big energy companies. But that’s another topic. At least this way, I can “take part” in it in some way.
My “dream house” would indeed be a completely off-grid home, so 100% self-sufficient. Truly, a house where I wouldn’t need to install any external connections anymore.
But unfortunately, that is still far too expensive, and at least for now, I can’t afford it. But the time for it will come eventually!
My “dream house” would indeed be a completely off-grid home, so 100% self-sufficient. Truly, a house where I wouldn’t need to install any external connections anymore.
But unfortunately, that is still far too expensive, and at least for now, I can’t afford it. But the time for it will come eventually!
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Bieber081531 Mar 2015 10:25Bauexperte schrieb:
You could have skipped solar and built according to the 15% rule.Could you briefly explain this rule? (Google mostly returns results related to the equity ratio, which is probably not what is meant here.)Similar topics