Dear community,
My wife and I are currently working with a general contractor to dive into the detailed building planning.
One of our main concerns is a proper air conditioning system for the house.
The project currently includes about 300m2 (3,230 sq ft) of living space plus a basement (ground floor + first floor + attic); KFW 55 standard plus photovoltaic system (sizing still to be decided).
We both have previous negative experience, having lived for over 10 years in apartments where indoor temperatures in summer uncontrollably reached 32-35°C (90-95°F). This has to stop.
Therefore, our original idea was to plan for air conditioning units in the key rooms right from the start (individual air conditioning units). Now I also understand that a heat pump can cool a few degrees below the outdoor temperature. At summer temperatures above 30°C (86°F), that would not be enough for me.
So my question is: do you have any experience with this? Does this thinking make sense, or would you say that a proper heat pump with cooling function is definitely sufficient?
Of course, we are aware that whole-house air conditioning adds extra costs. But is the investment worthwhile?
My wife and I are currently working with a general contractor to dive into the detailed building planning.
One of our main concerns is a proper air conditioning system for the house.
The project currently includes about 300m2 (3,230 sq ft) of living space plus a basement (ground floor + first floor + attic); KFW 55 standard plus photovoltaic system (sizing still to be decided).
We both have previous negative experience, having lived for over 10 years in apartments where indoor temperatures in summer uncontrollably reached 32-35°C (90-95°F). This has to stop.
Therefore, our original idea was to plan for air conditioning units in the key rooms right from the start (individual air conditioning units). Now I also understand that a heat pump can cool a few degrees below the outdoor temperature. At summer temperatures above 30°C (86°F), that would not be enough for me.
So my question is: do you have any experience with this? Does this thinking make sense, or would you say that a proper heat pump with cooling function is definitely sufficient?
Of course, we are aware that whole-house air conditioning adds extra costs. But is the investment worthwhile?
G
gregman228 Jul 2022 16:13lastdrop schrieb:
How the ground floor heats up naturally also depends on the orientation of the house.
Kitchen, dining, and living areas can get quite warm, partly because of the sun and partly because we use several electrical appliances there and spend a lot of time in these spaces. I would definitely include this in the air conditioning planning.Thanks for the feedback.I just don’t have a clear idea of how to size such an air conditioning system.
I assume the architect plans ventilation ducts early on. That’s why I feel adding an extra room for this wouldn’t cause significant additional costs. Is this a reasonable assumption? Or could someone explain how such a system is typically set up?
It is also important that the system can provide air conditioning on a room-by-room basis.
gregman22 schrieb:
I assume the architect is planning ventilation shafts early on. That’s why I feel that adding an extra room wouldn’t significantly increase the overall costs with this kind of effort. Is this a reasonable assumption? Or can someone explain how such a system is constructed? You could also consider having a ground air heat exchanger designed—essentially a buried pipe system—that passively preheats the air in winter using geothermal heat and delivers cooler air (for example, around 18°C (64°F) instead of 30°C (86°F)) into the house through a controlled ventilation system during summer. This provides some passive cooling in summer without maintenance and improves efficiency in winter. Additionally, include ample shading on the south and west sides and prepare for air conditioning in the bedrooms and living areas. The technology can still be retrofitted later once you’re living in the house if needed.
There are several approaches and options. Are you looking for a concealed system like in the USA, where only ventilation grilles are visible, or would you prefer a simple split system, which is common in Europe?
Cooling the floor through the heat pump is mostly a placebo effect. It only works if the house is located in a forested area with little sunlight. What is certain is that your 55-cm (22-inch) wall house will definitely warm up, and the attic will have a temperature similar to the apartments you have lived in, assuming there isn’t much shading around the building.
I would definitely cool the attic, the bedrooms, and the living areas. In practice, though, you will probably end up cooling almost the entire house (I’m not familiar with your floor plan).
Cooling the floor through the heat pump is mostly a placebo effect. It only works if the house is located in a forested area with little sunlight. What is certain is that your 55-cm (22-inch) wall house will definitely warm up, and the attic will have a temperature similar to the apartments you have lived in, assuming there isn’t much shading around the building.
I would definitely cool the attic, the bedrooms, and the living areas. In practice, though, you will probably end up cooling almost the entire house (I’m not familiar with your floor plan).
K
k-man20218 Jul 2022 19:34We live in a house with floor-to-ceiling windows facing southwest, without air conditioning. Yes, the bedroom on the upper floor gets warm despite having blinds. The main issue is that there is a terrace in front of the bedroom, which heats up and causes additional warmth in the evening, preventing the room from cooling down. Otherwise, the blinds are sufficient for us.
We are currently planning our new house, again with very large, ceiling-high glass surfaces and no air conditioning, which according to the architect is not necessary. Instead, we are focusing on passive solar design features such as projections and recesses that allow the low winter sun to enter while providing shade in the summer. This helps save on heating in winter and cooling in summer… that’s the plan.
We do not rely on the heat pump for cooling.
We are currently planning our new house, again with very large, ceiling-high glass surfaces and no air conditioning, which according to the architect is not necessary. Instead, we are focusing on passive solar design features such as projections and recesses that allow the low winter sun to enter while providing shade in the summer. This helps save on heating in winter and cooling in summer… that’s the plan.
We do not rely on the heat pump for cooling.
If this topic is that important, I would reconsider the summer thermal insulation (especially for the roof and wall construction) even more. Additionally, instead of building to KfW55 standard, consider a Passive House.
My bedroom (facing north and WITHOUT any heating or PC) remains bearable during summer anyway. A 2–5°C (4–9°F) reduction could be helpful during longer heat waves.
Everyone who says that only air conditioning can achieve what you want is probably right, but from my experience, the 2–3°C (4–5°F) passive cooling provided by our ground-source heat pump in our Passive House offers significant relief in summer. We’ve already had several sufficiently hot days to assess this.
If I were to build again, I would still add a central air conditioning system AND an earth tube ventilation system. Simply because I never realized how little electricity air conditioning actually consumes, especially in summer when you usually have surplus power from suitable photovoltaic panels.
My bedroom (facing north and WITHOUT any heating or PC) remains bearable during summer anyway. A 2–5°C (4–9°F) reduction could be helpful during longer heat waves.
Everyone who says that only air conditioning can achieve what you want is probably right, but from my experience, the 2–3°C (4–5°F) passive cooling provided by our ground-source heat pump in our Passive House offers significant relief in summer. We’ve already had several sufficiently hot days to assess this.
If I were to build again, I would still add a central air conditioning system AND an earth tube ventilation system. Simply because I never realized how little electricity air conditioning actually consumes, especially in summer when you usually have surplus power from suitable photovoltaic panels.
G
gregman228 Jul 2022 19:44Mycraft schrieb:
There are several approaches and options. Are you looking for a concealed system like in the USA, where you only see ventilation grilles, or do you want a simple, commonly used split system in Europe?
Cooling the floor via the heat pump is more or less placebo. It only works if your house is located in a forest with very little sun exposure. What is certain is that your 55-cm (22-inch) wall house will definitely warm up, and the attic will be similar to the apartments you have lived in, assuming there is not much shading around.
I would definitely cool the attic, the bedrooms, and also the living area. Basically, it will probably end up being almost the whole house anyway (I don’t know your floor plan). Basically, the main part of our garden does not have a perfect orientation, as it faces northwest. Nevertheless, the house will not be particularly well-protected. Of course, we will plan for appropriate shading in the building project, but I don’t want to rely solely on that, just as little as on the cooling function of the heat pump.
It looks like I will have to weigh the pros and cons between a multi-split system and a concealed/central system.
Regarding the room layout:
- Ground floor: Large living room–kitchen–dining area, probably over 70–90 m² (750–970 sq ft), utility room, restroom
- First floor: Master bedroom with walk-in closet and bathroom, 2 bedrooms, additional bathroom
- Attic: 2 offices, guest room, bathroom with shower
- Basement: Typical standard rooms plus wellness/sauna room plus fitness room, probably over 40 m² (430 sq ft)
- Separate apartment: I’m leaving this out of the consideration, as a single split unit will suffice there
Without deeper technical knowledge, I expect for such a large house to install 2 large split systems that cool several rooms — ideally as discreetly as possible. The cost will probably be somewhere below 10,000€.
I have no real sense or reference for how sensible a central system would be instead — including approximate costs and the pros and cons compared to split systems.
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