ᐅ Cooling via underfloor heating with a ground-source heat pump
Created on: 30 Apr 2015 11:27
S
SirSydom
Hello everyone,
I am very sensitive to heat, so this will be a major focus in our new build.
In addition to an automatic shading system with venetian blinds and roller shutters, and a solid construction method, as well as a ventilation system with a bypass (and possibly a ground heat exchanger), I am considering whether "passive" or "free" cooling through the underfloor heating system makes sense. This is said to have only low operating costs since only electricity for the pumps is required. The technology also seems quite simple—a heat exchanger between the brine circuit and the underfloor heating circuit, possibly with a few valves and a mixer.
Now I am wondering if the effort is worthwhile—does it really make a difference? Does anyone have a direct comparison in the same house, once with and once without?
My wife is still quite hesitant because she fears having cold feet. "In summer, I want to walk barefoot." Is this concern justified?
Are there alternatives for cooling that won’t immediately break the budget? A separate cooling ceiling would certainly cost several thousand euros.
With a conventional split air conditioning unit, I can already hear my wife complaining about drafts, so that option is probably off the table.
I am very sensitive to heat, so this will be a major focus in our new build.
In addition to an automatic shading system with venetian blinds and roller shutters, and a solid construction method, as well as a ventilation system with a bypass (and possibly a ground heat exchanger), I am considering whether "passive" or "free" cooling through the underfloor heating system makes sense. This is said to have only low operating costs since only electricity for the pumps is required. The technology also seems quite simple—a heat exchanger between the brine circuit and the underfloor heating circuit, possibly with a few valves and a mixer.
Now I am wondering if the effort is worthwhile—does it really make a difference? Does anyone have a direct comparison in the same house, once with and once without?
My wife is still quite hesitant because she fears having cold feet. "In summer, I want to walk barefoot." Is this concern justified?
Are there alternatives for cooling that won’t immediately break the budget? A separate cooling ceiling would certainly cost several thousand euros.
With a conventional split air conditioning unit, I can already hear my wife complaining about drafts, so that option is probably off the table.
I have a question about this. You can also route the supply air for the mechanical ventilation system through a pipe system buried underground. I understand that this only makes sense if you cannot use a ground source heat pump for cooling; it also makes sense in winter because the cold air is slightly pre-warmed. The reason I’m asking is that we cannot install a deep ground source heat pump. Natural gas is available on the property, and the connection will cost about 1000€ (approximately 1100 USD), which, from an economic perspective, currently rules out most other heating systems in my view (however, I have not yet completed the full calculations).
Best regards
Best regards
So, here is a mid-term report. Our cooling system is now running even at these temperatures. We have set it to 20°C (68°F). We are all still walking around barefoot. However, most rooms have hardwood or cork flooring. Only the hallway, bathrooms, and kitchens have tiles, which, at these high outdoor temperatures, is not uncomfortable but rather a nice, cool relief. Inside the house, it is really pleasant, and we don’t even want to go outside.
Hello, I’m bringing this topic back to life.
The reason is that we want to install a modulating brine heat pump (either a slinky trench collector or a geothermal borehole), which can also be used for cooling in the summer (this not only has a positive cooling effect but also supports faster and better ground recovery, especially with the slinky trench collector).
Generally, the supply temperature for underfloor heating pipes should not be set lower than about 19°C (66°F) due to dew point issues. Additionally, a controlled mechanical ventilation system with heat recovery is advisable (to remove moisture from the rooms).
Now my question: in the pink forum, there is a strong tendency to install a few additional pipes in the precast concrete slab for thermal activation of the concrete core.
However, this costs more (I know, not much if you install it yourself) and is simply a bit more effort (I know, this is limited as well) and may even raise structural concerns for the concrete slab. I also know that cooling through a concrete slab is generally more effective than through the floor. But now I would like to know:
is the floor really uncomfortable in summer with a supply temperature of around 19-20°C (66-68°F), or might it actually be pleasant and contribute a bit to cooling (or at least prevent significant warming) of the building?
Would you use the cooling via the underfloor heating pipes with the brine heat pump again, @Manu1976 and other forum members? Or would you invest the extra cost and effort into thermal concrete activation in the ceiling because—for example—20°C (68°F) cold tiles in the bathroom are uncomfortable or for other reasons?
Thanks for your opinions.
The reason is that we want to install a modulating brine heat pump (either a slinky trench collector or a geothermal borehole), which can also be used for cooling in the summer (this not only has a positive cooling effect but also supports faster and better ground recovery, especially with the slinky trench collector).
Generally, the supply temperature for underfloor heating pipes should not be set lower than about 19°C (66°F) due to dew point issues. Additionally, a controlled mechanical ventilation system with heat recovery is advisable (to remove moisture from the rooms).
Now my question: in the pink forum, there is a strong tendency to install a few additional pipes in the precast concrete slab for thermal activation of the concrete core.
However, this costs more (I know, not much if you install it yourself) and is simply a bit more effort (I know, this is limited as well) and may even raise structural concerns for the concrete slab. I also know that cooling through a concrete slab is generally more effective than through the floor. But now I would like to know:
is the floor really uncomfortable in summer with a supply temperature of around 19-20°C (66-68°F), or might it actually be pleasant and contribute a bit to cooling (or at least prevent significant warming) of the building?
Would you use the cooling via the underfloor heating pipes with the brine heat pump again, @Manu1976 and other forum members? Or would you invest the extra cost and effort into thermal concrete activation in the ceiling because—for example—20°C (68°F) cold tiles in the bathroom are uncomfortable or for other reasons?
Thanks for your opinions.
No, we don’t want proper air conditioning units.
It may not be real cooling in the strict sense, but on the other hand, maybe it is? If the bricks of the house reach 25°C (77°F) in the height of summer and the floor is “only” 20°C (68°F), that already contributes somewhat to cooling the air temperature (even if only minimally). Since not all surfaces in the room radiate heat—the floor feels rather cool—you definitely perceive it as cooler than without a cooling brine heat pump, right?
You say the ceiling or wall would be better—how much difference does that really make and why exactly?
It may not be real cooling in the strict sense, but on the other hand, maybe it is? If the bricks of the house reach 25°C (77°F) in the height of summer and the floor is “only” 20°C (68°F), that already contributes somewhat to cooling the air temperature (even if only minimally). Since not all surfaces in the room radiate heat—the floor feels rather cool—you definitely perceive it as cooler than without a cooling brine heat pump, right?
You say the ceiling or wall would be better—how much difference does that really make and why exactly?
The issue of dew point is less pronounced on ceilings and walls, and you have a considerable additional surface area. This results in extra cooling capacity.
With cooling through the floor, you can buffer 1-2°C (2-4°F). However, during prolonged heat periods, once the masonry has fully heated up, the cooling capacity is no longer sufficient to provide noticeable cooling. Only the feet feel cold.
Dehumidification is also important, which is achieved with an air conditioning system and strongly influences thermal comfort. This effect is absent in your case as well. Mechanical ventilation with heat recovery does not really dehumidify. During summer nights, the bypass operates, and most likely shuts off during the day to prevent further heating of the house.
Overall, it is better than nothing, but don’t expect miracles.
With cooling through the floor, you can buffer 1-2°C (2-4°F). However, during prolonged heat periods, once the masonry has fully heated up, the cooling capacity is no longer sufficient to provide noticeable cooling. Only the feet feel cold.
Dehumidification is also important, which is achieved with an air conditioning system and strongly influences thermal comfort. This effect is absent in your case as well. Mechanical ventilation with heat recovery does not really dehumidify. During summer nights, the bypass operates, and most likely shuts off during the day to prevent further heating of the house.
Overall, it is better than nothing, but don’t expect miracles.
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