Heat pump in connection with house air conditioning

2022-07-08 11:26:20

Dear community,

my wife and I are about to dive into detailed construction planning with a general contractor.
A major concern for us is proper air conditioning of the house.

The project currently has approx. 300m2 of living space plus basement (ground floor + upper floor + attic); KFW 55 plus photovoltaic (dimensioning still open).

We are both pre-damaged, as we have lived >10 years in apartments that gave us uncontrollably 32-35 degrees in summer. That has to end.
That is why the original idea was to plan house air conditioning for the most important rooms from the start (individual air conditioners). Now I also know that a heat pump can cool down to a few degrees below the outside temperature. At 30 degrees plus in summer, that would not be enough for me.

Therefore the question: Do you have experience with that? Do the thoughts make sense or do you say a proper heat pump with its cooling function is definitely sufficient?

The fact that house air conditioning costs extra money is known. But is the investment worth it?

2022-07-08 12:01:37

1. New houses stay cool inside much longer than old buildings. However, once heat gets in, it's also much harder to get it out again. 2. Because of point 1, a lot of thought goes into sun protection/shading during house planning. 3. Yes, a heat pump can cool. But since it only circulates "cool" water through the surface heating and does not dehumidify, the effect is quite limited. Why? Because with higher cooling capacity / very low temperatures, condensation would occur in the floor (with underfloor heating). So you can maybe cool down about 3 degrees. Noticeable, but absolutely not comparable to an air conditioner. Combined with well-planned sun protection, though, that might be enough. The perception is individual – some say "great," others find 22 degrees indoors already too warm. You will definitely not reach the 32-35 degrees of your old residence in the new build. 4. Whether it’s worth it is relative. Heating is worth it, because otherwise you will have a problem in winter. An air conditioner is financially not really worthwhile, but maybe for comfort it is ;). I hope the info helps you a bit. So far, I have not used the cooling function of my heat pump because it has not been too warm. Although with your seven-figure investment, I would provocatively claim that spending a few € for (partial) air conditioning would be appropriate for the property.

2022-07-08 12:08:53

1. New houses remain cool inside for much longer than old buildings. However, once heat is inside, it's also much harder to get it out. 2. Because of 1., careful consideration is given to sun protection/shading during house planning. 3. Yes, a heat pump can cool. But since it only circulates "cool" water through the underfloor heating system and does not dehumidify, the effect is quite small. Why? Because with higher cooling capacity / very low temperatures, condensation would form in the floor (at the underfloor heating). Thus, you may be able to cool down by about 3 degrees. Noticeable, but absolutely not comparable to an air conditioner. However, combined with well-planned sun protection, this can be sufficient. The feeling is individual - some say "great," others already find 22 degrees inside the house too much. You will definitely not reach the 32-35 degrees of your old residence in the new building. 4. Whether it is worthwhile is relative. A heating system is worthwhile because otherwise, you have a problem in winter. An air conditioner is financially not worthwhile, but maybe for well-being it is ;). I hope the information helps you a little. So far, I have not used the cooling function of my heat pump because it was not too warm. Although, considering your seven-figure investment, I would provocatively say that the few euros for a (partial) air conditioning would suit the property.

That was a really great and helpful post! Thank you!

2022-07-08 13:03:48

We have underfloor cooling in the company. It helps a bit, but the other problems outweigh it. Our problem is that the blinds go up at every gust of wind and large window areas have to be opened like two arrow slits. The air exchange is so poor that even on rainy days with 15 degrees you can't lower the temperature. In two offices, larger windows (emergency exits) are installed, and it is much better there.

The key is to have proper shading so that the heat stays outside and to be able to ventilate out any heat at cooler outside temperatures (evenings, nights). A garden area with lots of greenery and shade in the main wind direction also helps; if possible, avoid heat buildup caused by terraces. (In our current apartment, we have the problem that the balcony faces west and after sunset on hot days there is still so much heat that we cannot ventilate through it until it has radiated off for 1-2 hours.)

The question is, what temperature do you want and which rooms would you like to cool?

2022-07-08 16:05:44

I generally assume that the ground floor is less affected by the heat problem than the upper floor/ attic. Therefore, the following rooms would be the focus for cooling: bedroom, children's rooms 1&2 - on the upper floor; 2 office rooms and guest room in the attic; possibly fitness room in the basement!?

I exclude the granny flat, which will be built either as an extension or as a separate building. This could be cooled with a single air conditioning unit if necessary, as it will not be constantly occupied.

2022-07-08 16:09:15

How the ground floor heats up naturally also depends on the orientation of the house.

Kitchen/Dining/Living can become quite warm, on the one hand because of the sun, on the other because we operate quite a few electrical appliances there and of course spend a long time there. I would definitely include that in the air conditioning.

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Heat pump in connection with house air conditioning

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