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?
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nordanney27 Mar 2015 18:46In summer, this is correct (although at night I prefer to keep the pollen outside and use the filtered air from the mechanical ventilation with heat recovery), but summer is quite short for us.
What about the mentioned odors from October to May, when it is not midsummer?
What about the mentioned odors from October to May, when it is not midsummer?
Among other things, the initial post includes this statement:
Based on this statement, I assume that a mechanical ventilation system with heat recovery might not be necessary. Someone who emphasizes their ventilation habits (this is a neutral observation) will not give up fresh air indoors during autumn and winter either. This doesn’t mean ventilation through a mechanical system, but rather fresh air from open windows.
And this is completely counterproductive to the energy comfort of a new build. We all want to build energy-efficiently so that heat stays inside and cold stays outside.
I’m not an expert in heating technology, but I’d like to ask those here who know better:
Is it basically possible to skip the KfW55 standard given the statements above?
asks Yvonne
Nina132 schrieb:
5. I like to ventilate a lot.
Nina132 schrieb:
At least in summer, I won’t be able to change my ventilation habits. We have cats, cat food smells, and I’m allergic to cooking fumes, so I like to open the window right away. I want to live in my house the way I want, and I’m also willing to pay more for that.
Based on this statement, I assume that a mechanical ventilation system with heat recovery might not be necessary. Someone who emphasizes their ventilation habits (this is a neutral observation) will not give up fresh air indoors during autumn and winter either. This doesn’t mean ventilation through a mechanical system, but rather fresh air from open windows.
nordanney schrieb:
You can only get more fresh air with permanently open windows and doors—which can get pretty cold in winter.
And this is completely counterproductive to the energy comfort of a new build. We all want to build energy-efficiently so that heat stays inside and cold stays outside.
I’m not an expert in heating technology, but I’d like to ask those here who know better:
Is it basically possible to skip the KfW55 standard given the statements above?
asks Yvonne
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Bauexperte27 Mar 2015 20:00Yes; from an economic perspective anyway ...
Regards, Bauexperte
Bauexperte
Regards, Bauexperte
Bauexperte
M
mcarstensen27 Mar 2015 23:06A ground source heat pump would have been very expensive for us, including drilling, since there was no suitable land area and I didn’t want to do that anyway. (As described earlier, we had a quote.) It may be true that the electricity consumption is factored into the annual performance figure, but I still believe that the electricity also has to be generated. And very few people actually use “green” electricity.
550 euros refers to the total gas bill for the entire last year, including hot water. We have solar thermal panels on the roof, as we have to comply with the regulations. Economically, though, it doesn’t make sense… but in our case it is the cheapest solution to satisfy the lawmakers.
Some acquaintances have an air source heat pump and currently pay 130 euros per month for electricity. Whether it is incorrectly set or something else, I obviously don’t know. And I don’t really care.
Ultimately, everyone has to decide for themselves.
Of course, a house, car, or smartphone don’t pay for themselves, but in our case it is true that we do not have unlimited financial resources. At some point you have to think “economically.” If that didn’t matter, we would all be driving Porsches or similar. But in reality, there are people who pay attention to reasonable and economical consumption when it comes to cars, because of the ongoing costs.
I am simply curious to see how this develops. I am not against alternative energies (on the contrary, I get my electricity exclusively from certified green providers and I am involved in a wind farm myself), but I am against everything being nicely calculated and talked up.
In my view, a heat pump can only be considered “alternative energy” if it is actually operated “green” and not powered by electricity from a coal power plant 100 kilometers (60 miles) away.
But that is of course a fundamental point of view.
550 euros refers to the total gas bill for the entire last year, including hot water. We have solar thermal panels on the roof, as we have to comply with the regulations. Economically, though, it doesn’t make sense… but in our case it is the cheapest solution to satisfy the lawmakers.
Some acquaintances have an air source heat pump and currently pay 130 euros per month for electricity. Whether it is incorrectly set or something else, I obviously don’t know. And I don’t really care.
Ultimately, everyone has to decide for themselves.
Of course, a house, car, or smartphone don’t pay for themselves, but in our case it is true that we do not have unlimited financial resources. At some point you have to think “economically.” If that didn’t matter, we would all be driving Porsches or similar. But in reality, there are people who pay attention to reasonable and economical consumption when it comes to cars, because of the ongoing costs.
I am simply curious to see how this develops. I am not against alternative energies (on the contrary, I get my electricity exclusively from certified green providers and I am involved in a wind farm myself), but I am against everything being nicely calculated and talked up.
In my view, a heat pump can only be considered “alternative energy” if it is actually operated “green” and not powered by electricity from a coal power plant 100 kilometers (60 miles) away.
But that is of course a fundamental point of view.
ypg schrieb:
Among other things, the initial post contains the following statement:
And based on this statement, I assume that a mechanical ventilation system with heat recovery can be skipped. Anyone who pays attention to their ventilation habits (this is a neutral observation) will not forego fresh air inside the house during autumn and winter. And this does not mean some ventilation system, but fresh air from an open window. So, can one basically not do without KfW55 with the statements above?
asks YvonneThis is a question I have been wondering about for some time as well. The problem is, my partner is quite fixated on this KfW standard. Initially and also up to now, we have had one provider in mind who advertises KfW55. We share the opinion that building an energy-efficient house makes sense. Whether it absolutely has to be KfW55, though, is debatable. It’s not really about the “ecological conscience” — I put that in quotation marks because I’m aware that’s often just lip service. There are other issues our society should address first. It’s more about ongoing costs, as well as value stability and resale value. And yes, it’s about fresh air; mechanical ventilation with heat recovery isn’t really my favorite. Our plot is directly next to a forest, and I like how the air smells there, even if probably everyone is rolling their eyes right now
mcarstensen schrieb:
550 euros refers to the entire gas bill for the whole last year. Naturally including hot water. We have solar thermal on the roof since we have to “follow the rules.” Economically, though, it doesn’t really make sense… But it is the cheapest solution for us to satisfy the regulators… What kind of house have you built? KfW or Energy Saving Ordinance (EnEV)?
Yes, solar seems to be the crucial point. Without solar, you won’t even reach KfW70, and that should probably be the goal (from 2016, as far as I know, it corresponds to the Energy Saving Ordinance, making it sensible in terms of value). I’m currently considering whether solar might still make sense in some form. Just to emphasize, our house is located on a steep north-facing slope. I’m attaching the architect’s drawings; you can see the natural slope well. From the street (which faces north) it first rises about 3m (10 feet). The garage will be built partly underground there, and a staircase leads up to the house. Then the house is semi-embedded so that, as mentioned before, we have some usable outdoor area at the back (there is only a 90cm (35 inches) elevation over 9m (30 feet), which is manageable). Further uphill (to the right in the side view = south), there is a forest with tall trees after about 200-300m (650-980 feet). From October to March, there isn’t much sun except at midday. However, I assume solar panels are not that effective in winter in other locations either. Or am I mistaken? It’s just quite obvious since no one in the municipality has solar, while the neighboring community on the other side of the river does.
Many thanks so far for your replies
Nina132 schrieb:
From October to March, there is accordingly not much sun except around midday.But there is still sunlight on the south-facing roof, right?
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