ᐅ Air-to-Air vs. Air-to-Water Heat Pump for a KfW55 House – Importance of Cooling Function
Created on: 26 Jun 2023 14:32
N
nanella
Hello everyone,
we are currently deciding between several prefab house suppliers, and a major difference is the heating system offered. Some suppliers install an air-to-air heat pump as standard (cooling available at extra cost), while others provide an air-to-water heat pump with underfloor heating and a ventilation system with heat recovery (an air conditioning unit can be added). Geothermal or groundwater as a heat source will likely not be an option for the plot we are currently considering. It will be a KFW 55 house, initially without photovoltaics for cost reasons, but solar panels are planned to be added later.
We have already read quite a bit on the topic, but as laypeople, we find it difficult to make a decision regarding the heating system. It is important to know that we are very sensitive to heat and want to include active cooling right from the start. In the worst case, we would need to heat/cool only individual rooms.
These are the advantages and disadvantages we know so far:
In principle, this results in 3 options that we are currently considering (we were advised against underfloor heating with cooling function for the reasons mentioned):
Which option would you prefer, or do you see another solution? Do you have any ideas which option would be better in terms of running costs? Because we probably have a rather expensive plot and need to watch costs during construction, air-to-air currently sounds like the better solution to us.
We would appreciate your assessments.
we are currently deciding between several prefab house suppliers, and a major difference is the heating system offered. Some suppliers install an air-to-air heat pump as standard (cooling available at extra cost), while others provide an air-to-water heat pump with underfloor heating and a ventilation system with heat recovery (an air conditioning unit can be added). Geothermal or groundwater as a heat source will likely not be an option for the plot we are currently considering. It will be a KFW 55 house, initially without photovoltaics for cost reasons, but solar panels are planned to be added later.
We have already read quite a bit on the topic, but as laypeople, we find it difficult to make a decision regarding the heating system. It is important to know that we are very sensitive to heat and want to include active cooling right from the start. In the worst case, we would need to heat/cool only individual rooms.
These are the advantages and disadvantages we know so far:
| Heat Pump | Advantages | Disadvantages |
| Air-to-Air with Cooling Function |
|
|
| Air-to-Water with Underfloor Heating + Air Conditioning |
|
|
| Air-to-Water with Underfloor Heating with Cooling Function |
|
|
In principle, this results in 3 options that we are currently considering (we were advised against underfloor heating with cooling function for the reasons mentioned):
- Install air-to-air heat pump with cooling function
- Install air-to-water with underfloor heating, add air conditioning when photovoltaics are installed, and live with the heat until then
- Install air-to-water with underfloor heating and air conditioning, tolerate high cooling costs until photovoltaics are added
Which option would you prefer, or do you see another solution? Do you have any ideas which option would be better in terms of running costs? Because we probably have a rather expensive plot and need to watch costs during construction, air-to-air currently sounds like the better solution to us.
We would appreciate your assessments.
Thank you very much for all the feedback! It has already given us a lot to think about.
Raynaud’s syndrome (cold in hands or feet = pain). For me, this means that even in summer I wear cozy socks and thick slippers indoors. However, our current apartment is very poorly insulated; hopefully, this wouldn’t be as much of an issue in a new build. Nevertheless, cold feet are something I would prefer to avoid.
My partner also has no problem walking barefoot on our floors all year round; as mentioned, my health issues make things more difficult for me. For most people, cooling via underfloor heating certainly wouldn’t be a problem. By the way, we are building in Bremen.
That is definitely part of the planning, but we also want to include active cooling.
RotorMotor schrieb:
What health reasons are there against chilled floor cooling?
Raynaud’s syndrome (cold in hands or feet = pain). For me, this means that even in summer I wear cozy socks and thick slippers indoors. However, our current apartment is very poorly insulated; hopefully, this wouldn’t be as much of an issue in a new build. Nevertheless, cold feet are something I would prefer to avoid.
WilderSueden schrieb:
I think expectations for the cooling are much higher than what it will actually deliver. At the office, I often walk barefoot (IT people are allowed to!) and it feels cool on the carpet but not cold. Uncooled tiles feel worse.
HeimatBauer schrieb:
I’ve mentioned this in a few other threads, briefly: I have cooling through the regular underfloor heating system, controlled by the photovoltaic system. It works great and NO, no one complains about cold feet. The heat simply disappears. My system suffices mainly due to a) a very well-insulated house and b) the location at 550m (1800ft) in the pre-Alps region – in Cologne on the Rhine, it probably wouldn’t be enough. A real air conditioning system just has much more power and also dehumidifies.
My partner also has no problem walking barefoot on our floors all year round; as mentioned, my health issues make things more difficult for me. For most people, cooling via underfloor heating certainly wouldn’t be a problem. By the way, we are building in Bremen.
WilderSueden schrieb:
If you are sensitive to heat, I would definitely consider shading. Don’t forget the issue of lighting with shading; with proper planning, you can shade the sunny sides well and let light in from the other sides.
That is definitely part of the planning, but we also want to include active cooling.
H
HeimatBauer26 Jun 2023 16:35If you’re always wearing slippers indoors anyway, where’s the problem? When in doubt, just visit a place like that. We just had guests over the weekend, and as usual, they were absolutely thrilled with the cooling.
There was a recent thread here about the fundamental decision between an air-to-air heat pump and an air-to-water heat pump.
There was a recent thread here about the fundamental decision between an air-to-air heat pump and an air-to-water heat pump.
What about humidity levels when using underfloor cooling? When cooling down, the moisture has to go somewhere, and it will likely accumulate on walls or furniture. We are currently building a KFW55 standard house with an air-to-water heat pump and were considering activating the cooling function as soon as the heating system is installed.
Since new buildings tend to have high humidity anyway, I initially decided to avoid using the cooling and plan to upgrade later with proper air conditioning and photovoltaic panels—once there is some extra budget or loan interest rates become more favorable. I remember a thread here from a few days ago where there was a real struggle against humidity.
Since new buildings tend to have high humidity anyway, I initially decided to avoid using the cooling and plan to upgrade later with proper air conditioning and photovoltaic panels—once there is some extra budget or loan interest rates become more favorable. I remember a thread here from a few days ago where there was a real struggle against humidity.
H
HeimatBauer26 Jun 2023 16:51As mentioned there, the cooling switches off before it reaches a dangerous level. I have not noticed any "battle against moisture" and cannot understand it—especially not when it comes to furniture (!).
Retrofitting is pointless. The cooling-capable system differs in its control and the switchable thermostats. Install everything and then tear it out? No way.
I would definitely install a proper air conditioning system immediately as well.
Retrofitting is pointless. The cooling-capable system differs in its control and the switchable thermostats. Install everything and then tear it out? No way.
I would definitely install a proper air conditioning system immediately as well.
K
KarstenausNRW26 Jun 2023 17:40nanella schrieb:
Raynaud’s syndrome (cold in hands or feet = pain). For me, this means I have to wear cozy socks and thick slippers indoors even in summer. Just to mention: What do you think a tiled floor feels like in winter with an air-to-air heat pump? THAT’s when you really have an issue. With underfloor heating, the floor feels warm underfoot. With an air-to-air heat pump, the floor is simply cold – of course, it has to be significantly colder since it’s not heated. In that case, you absolutely need solid wood flooring so that not everyone (not just you) has cold feet.
H
HeimatBauer26 Jun 2023 17:46Yes, strangely enough, having a cold floor all year round is quite stylish and cool in an older building, but a cooled underfloor heating system in the middle of summer is something I find "terrible to imagine" and "wouldn’t want even if it were given to me." Well, I also imagine that a Bugatti Veyron would be impractical to park, and I wouldn’t want that even if it were given to me!
Similar topics