Heat pump in connection with house air conditioning

How the ground floor heats up naturally also depends on the orientation of the house. Kitchen/dining/living areas can get quite warm, on the one hand because of the sun, on the other because we operate quite a few electrical devices there and of course spend a long time there. I would definitely include that in the air conditioning.

Thanks for the feedback. I simply have no sense of how such an air conditioning system can be sized. I assume the architect plans ventilation shafts early on. Therefore, my feeling is that with this effort, an additional room does not cause much extra cost. Is that the right way of thinking? Or can someone explain to me the setup of such a system? It is of course also important that it can be air-conditioned room by room.

I suspect the architect plans ventilation shafts early on. That’s why my feeling tells me that with this effort an additional room doesn’t cause much extra cost. Is this a correct way of thinking? Or can someone explain to me the setup of such a system?

You could also have a [Luftbrunnen] planned, basically a geothermal heat exchanger or a long buried pipe that pre-warms the air via geothermal heat in winter and then brings cooler air (e.g. 18° instead of 30°) into the house in summer via controlled residential ventilation. This thus passively and maintenance-free provides a bit of cooling in summer or improves efficiency in winter. In addition, generous shading options on the south and west sides and prepare air conditioning for the bedrooms and living areas. If you then live inside, you can possibly retrofit the technology later.

There are several approaches and several options. Are you thinking of a hidden system like in the USA where you only see ventilation grilles, or should it be a simple and common split system in Europe? The floor cooling via the heat pump is rather placebo. It only works if the house is located in the forest and gets little sunlight. What is certain is that your 55-year-old house will definitely become warm, and in the attic it will be similar to the apartments you have lived in, provided you don’t have much shading around it. I would definitely cool the attic, the bedrooms, and also the living area. In principle, it is probably almost the entire house anyway (I don’t know your floor plan).

We live in a house that has floor-to-ceiling windows facing SW, without air conditioning. Yes, the bedroom on the upper floor gets warm despite the blinds. The main problem is that there is a terrace in front of the bedroom that heats up and thus provides additional warmth in the evening and prevents cooling down. Otherwise, the blinds are sufficient for us.

We are currently planning our new house, again with very large, floor-to-ceiling glass surfaces, without air conditioning, which according to the architect is not necessary. Instead, we focus on constructive sun protection such as projections and recesses that let in the low winter sun and provide shade in summer. This saves heating in winter and cooling in summer.... That’s the plan.

We do not rely on the heat pump for cooling.

If the topic is that important, I would reconsider the summer thermal insulation (especially the roof and wall construction) even more. Also, possibly build a passive house instead of KfW55.
My bedroom (facing north and WITHOUT any heating and thus without a PC) remains bearable in summer nonetheless. 2-5° less, however, would not hurt during a longer heat period.

Everyone who claims only an air conditioner can achieve what you are looking for is probably right, but I can say from experience that the 2-3° passive cooling from our brine-water heat pump in our passive house provides me with significant "relief" in summer. It has already been hot enough outside for several days now to assess that.

If I were to build again, I would still supplement the future house with both a central air conditioner AND an earth-air heat exchanger. Simply because I never knew that air conditioners consume so little electricity, which you usually have left over in summer with suitable photovoltaics.

There are several approaches and several options. Are you thinking of a hidden system like in the USA where you only see ventilation grilles, or should it be a simple and common split system as used in Europe?

Cooling the floor via the heat pump is more of a placebo effect. That only works if the house is located in the woods and gets little sunlight. What is certain is that your 55er house will definitely get warm and the attic will be similar to the apartments you’ve lived in, provided you don’t have much shading around it.

I would definitely cool the attic, the bedrooms, and also the living area. In principle, though, it will probably be almost the entire house (I don’t know your floor plan).

Basically, the main part of our garden does not have a perfect orientation, since it faces northwest. Nevertheless, the house will not be particularly well protected. Of course, we will plan appropriate shading into the construction project, but I do not 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 decision between a multi-split and a hidden/central system.

Regarding the room layout:
- Ground floor: Large living room-kitchen-dining room area with presumably >70-90m2, utility room, WC
- Upper floor: Master bedroom with wardrobe and bathroom, 2 bedrooms, additional bathroom
- Attic: 2 office rooms, guest room, bathroom with shower
- Basement: typical standard rooms plus wellness/sauna room plus fitness room (probably >40m2)
- Separate apartment: I am excluding this from consideration, as a single split unit will suffice there.

Without deeper expertise, I expect for the large house two large split systems that cool several rooms – ideally as inconspicuous as possible. The cost will probably end up somewhere under €10,000.

I lack any sense or reference as to how sensible a central system would be instead – plus rough costs and pros/cons compared to split.