ᐅ Which heating system? Air source heat pump / gas / geothermal heating
Created on: 26 Mar 2015 19:57
N
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?
ypg schrieb:
Thanks for the photos explaining this
Funny: do they all have the same houses there? Or is the roof pitch regulated? That hits our sore spot. Yes, the community prefers gray, quite conservative pitched roofs... grumble... we actually wanted a flat roof.
M
mcarstensen29 Mar 2015 22:59So, we maintain a temperature of 20-21 degrees Celsius (68-70°F) throughout the entire house. We shower as usual, and the house is about 135m² (1450 sq ft) in size. Of course, the stove helps a bit, but it mainly serves to create a cozy atmosphere.
And we always shower with warm water, not cold—I don’t know how it is for you. To be fair, though, last winter was certainly not particularly harsh for us.
And just for your information: last summer was very sunny. From June until the end of August, I only used 3m³ (106 cubic feet) of gas. So the solar system really has some benefits…
I don’t know which air-source heat pump was installed or the exact setup. The house size is also estimated to be around 120-130m² (1290-1400 sq ft). As I mentioned before, it doesn’t matter much to me. Everyone has to decide for themselves. I was told the cost was about 130 euros without household electricity. But anyway…
Of course, I understand that everyone who has invested in a heat pump will naturally think very highly of it. I would too if I had spent that much money on it…
Oh, and regarding the “green” electricity: I have to trust the “certificates,” but at least I try and pay attention to it. I’m happy to pay a few cents more per kWh for that.
And we always shower with warm water, not cold—I don’t know how it is for you. To be fair, though, last winter was certainly not particularly harsh for us.
And just for your information: last summer was very sunny. From June until the end of August, I only used 3m³ (106 cubic feet) of gas. So the solar system really has some benefits…
I don’t know which air-source heat pump was installed or the exact setup. The house size is also estimated to be around 120-130m² (1290-1400 sq ft). As I mentioned before, it doesn’t matter much to me. Everyone has to decide for themselves. I was told the cost was about 130 euros without household electricity. But anyway…
Of course, I understand that everyone who has invested in a heat pump will naturally think very highly of it. I would too if I had spent that much money on it…
Oh, and regarding the “green” electricity: I have to trust the “certificates,” but at least I try and pay attention to it. I’m happy to pay a few cents more per kWh for that.
Ok, thanks for the information about the underfloor heating. The heating load calculation is clear; we will probably do that soon. However, I wonder how accurate something like this can be when it is currently a two-person household, both working full-time, and this might change in a few years.
Yes, the architect and we have a few nice roof ideas, but the eaves height is causing us some issues in this regard. From the front, though, we can manage the flat roof view. :-/
Gas combined with solar sounds good. I think if we had a well-designed solar system, that might be the best option. But how can I still combine gas in a sensible way to comply with KfW standards?
Yes, the architect and we have a few nice roof ideas, but the eaves height is causing us some issues in this regard. From the front, though, we can manage the flat roof view. :-/
Gas combined with solar sounds good. I think if we had a well-designed solar system, that might be the best option. But how can I still combine gas in a sensible way to comply with KfW standards?
With proper insulation, the following combination could be used: gas boiler + heat pump for domestic hot water + photovoltaic system = KfW55 standard.
Controlled ventilation would then be mainly for comfort inside the house, but not strictly necessary to meet KfW requirements. The heat pump for domestic hot water is even more cost-effective than solar thermal systems, and photovoltaic systems currently pay for themselves (although large profits are no longer common).
Controlled ventilation would then be mainly for comfort inside the house, but not strictly necessary to meet KfW requirements. The heat pump for domestic hot water is even more cost-effective than solar thermal systems, and photovoltaic systems currently pay for themselves (although large profits are no longer common).
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