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?
B
Bauexperte28 Mar 2015 23:45Good evening,
Regards, Bauexperte
mcarstensen schrieb:I would be interested to know the size of your house and your shower and bathing habits.
550 euros refers to the total gas bill for the entire last year. Of course, including hot water.
mcarstensen schrieb:You could have opted out of solar and built according to the 15% rule instead.
We have solar thermal panels on the roof, since we have to comply with the "rules."
mcarstensen schrieb:These simplified statements do more harm than good in clarifying the topic! How large is your friends’ house, which air-to-water heat pump is installed, and does the 130 euros refer solely to the air-to-water heat pump or does it also include household electricity?
Friends have an air source heat pump and currently pay 130 euros per month in electricity costs. Whether it’s incorrectly set or something else, I don’t know. Doesn’t concern me.
mcarstensen schrieb:I always smile when I read statements like that. Can you be sure that you actually receive “clean” electricity?
I am not against alternative energies (on the contrary, I get my electricity exclusively from certified green suppliers
Regards, Bauexperte
Bauexperte schrieb:
I’m curious about the size of your house and your showering and bathing habits.The year the house was built and the indoor temperatures would also be interesting.
If I’m shivering at 18°C (64°F) in winter, I’m probably using about 500 per year as well.
ypg schrieb:
But on the south-facing roof, right?Well, not exactly. As I mentioned, it’s a river valley with steep slopes on both sides. In winter, the sun quickly disappears behind the hill. To clarify, I’m attaching a few pictures. The slope rising in the photos faces south; in the third picture, you can see the trees at the end of the hill. In the second and last pictures, you can see the other side of the river valley, where the sun still shines in places.
The roof, however, would be oriented toward the south.
Since we are currently dealing with this topic: especially with heat pumps (whether air-source or ground-source), you need to pay close attention to the system design. Perform a room-by-room heating load calculation and size your underfloor heating accordingly – or make sure that the supplier or a specialized HVAC engineer does this for you. Don’t accept vague answers like “we install 15 cm (6 inches) everywhere.”
A list of current heat pump coefficients of performance (COPs) is available from BAFA – along with many other useful details on this topic.
A list of current heat pump coefficients of performance (COPs) is available from BAFA – along with many other useful details on this topic.
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