ᐅ Is an air conditioning system necessary for a south-facing slope location?

hampshire schrieb:

People who appreciate nature, fresh air, and the scent of garden, forest, and meadow are better off finding other solutions than shutting themselves up hermetically sealed in buildings all year round, summer and winter alike.

I just find it really hard to sleep, cook, work from home, and do similar activities like that…

hampshire schrieb:

So we install air conditioners. Great energy saving.

Compared to the energy we waste heating, that’s nothing. In my old building, which I keep under 24°C (75°F), it’s about a factor of 60.

Guido1980 schrieb:

Additionally, you will find the current floor plans showing which rooms might be equipped with air conditioning units, along with some pictures of the exterior view.

In that case, I would install a single unit as high up as possible in the gallery, which should then run continuously (from May to October) to keep the house dry and cool in combination with the underfloor cooling. Feel free to prepare the other rooms—I suspect you won’t need it.

Guido1980 schrieb:

By the way, the first quote for equipping the four rooms with a multi-split air conditioning system, including materials and installation, is about 15,000 €!

That’s too expensive, especially for a new build. Rough rule of thumb: 1,000 €/kW of cooling capacity. A new building shouldn’t need more than 5 kW. If you operate the unit like your heating (turn it on in summer, off otherwise), often just one indoor unit is enough to go from “I’m dying here” to “this is bearable”—especially combined with thermal mass or passive cooling.
If you want to maintain a steady 20°C (68°F) all the time, you’ll need to spend more, but nowhere near 15k.

Guido1980 schrieb:

Why is electricity consumption negligible?

I have two reference points: 140 m² (1507 sq ft) old building, constant cooling at 23–24°C (73–75°F), about 500 kWh, around €150 per year.
135 m² (1453 sq ft) new build, cooling on demand, 300 kWh, about €90 per year.
These are average values from the last two or three summers, which were not exactly cold.
I consider that negligible.

hampshire schrieb:

People who appreciate nature, fresh air, and the scents of garden, forest, and meadow should find other solutions than sealing themselves hermetically inside buildings during summer and winter.

These two things are by no means mutually exclusive.

Deliverer was right to suggest placing a device as high as possible. Or alternatively, three devices in the southern rooms. Cooling on demand or continuously—both are possible and both are effective.

Guido1980 schrieb:

Are there any practical experiences with cooling via mechanical ventilation with heat recovery and underfloor heating? From what I’ve read, it seems the cooling capacity there is very limited, and actual cooling during the peak of summer is only possible with an air conditioning system.

Mechanical ventilation with heat recovery is comparable to a television in terms of heat output. In other words, a regular TV produces about as much waste heat during operation as the ventilation system can cool. So, it’s not really significant. The purpose of mechanical ventilation is to provide fresh air, not to cool or heat the indoor air.

With underfloor heating, you end up with a cold and somewhat unpleasant floor surface but gain 2-3 degrees Celsius (4-5°F), mostly near the floor. At head height, temperatures of 27-28°C (81-82°F) remain. Physics can’t be bypassed.

Another important factor is humidity, not just temperature. To achieve a comfortable indoor climate, dehumidification is necessary.

15K is definitely way too expensive.

Deliverer schrieb:


That is – especially for new builds – too expensive. A rough rule of thumb: 1000 €/kW cooling capacity. A new build shouldn’t need more than 5 kW. If you operate the system like your heating (turn it on in summer, turn it off), often just one indoor unit is enough to go from “I’m dying” to “this is bearable.” Especially when combined with ground source cooling.
If you want to keep it constantly at 20°C (68°F), you have to spend a bit more. But certainly not 15k.

I have two reference points: 140 m² (1506 sq ft) older building, continuous cooling at 23-24°C (73-75°F), 500 kWh, so about 150 € per year.
135 m² (1453 sq ft) new build, cooling as needed, 300 kWh, so around 90 € per year.
These are average values from the past two or three summers. And they were not particularly cold.
I consider that negligible.

So the air conditioning contractor planned for 5 indoor units and 1 outdoor unit. Three indoor units in the attic for the three rooms, each with 2 kW, plus 2 indoor units for the living/dining area with 2.5 kW each. So that adds up to 11 kW. Furthermore, it has to be considered that the house has over 300 m² (3229 sq ft) of living space! The living room alone is 64 m² (689 sq ft).

So, relative to that, the costs make more sense.

I also got a quote just for the units without installation from a wholesaler. They offered three indoor units for the attic with 2.3 kW each, plus one unit with 5.3 kW for the living room on the ground floor, totaling 10,000 €. But that doesn’t include any installation.

Mycraft schrieb:


Deliverer is right: one unit as high up as possible. Or three in the south-facing rooms. Cooling on demand or continuously, both are possible and effective.

Another issue is humidity, not just temperature. If you want a comfortable indoor climate, you need dehumidification.

15k is definitely way too expensive.

I don’t know if one unit in the gallery is very effective; won’t the cool air just fall through the open space in the gallery down to the basement and not reach the rooms where it’s needed?

To illustrate, here is a picture from inside the house.

I can get humidity under control with the planned controlled mechanical ventilation with heat recovery, right?

Guido1980 schrieb:

I also received a quote just for the units without installation from the wholesaler. They offered three indoor units for the attic, each with 2.3 kW, and one 5.3 kW unit for the living room on the ground floor, totaling €10,000. However, the complete installation is not included.

Yes, the main cost driver is the five indoor units. If you reduce that to only three units, the costs are roughly halved. (Of course, it’s also possible to install just three units for €15K—no problem.)

If you find €15K acceptable, then go for it… I mean, it’s reasonable. The house will definitely be comfortably cool with those five units. So what’s the question? Whether it will get cool or if there’s a way to save money?

By the way, what is the wall structure? And what do you have in mind regarding smart home features?

Guido1980 schrieb:

I’m not sure if a unit in the gallery space would be very effective, since the cold air would fall through the open gallery all the way down to the basement and not reach the rooms where it’s needed?!?

The air is dehumidified and falls downward. Warm air flows in and is also dehumidified and cooled, coming from all rooms as long as the doors are open. This process continues until the set temperature is reached. Of course, having multiple indoor units makes this faster and more effective.

Guido1980 schrieb:

I thought I could control the humidity with the planned controlled residential ventilation system, right?

No, the controlled residential ventilation system doesn’t work that way. It only dehumidifies the air in winter because there is a difference between indoor and outdoor air humidity. In summer, when indoor and outdoor air have roughly the same humidity level, the ventilation system does not dehumidify.

The function of the controlled residential ventilation system is almost identical to a car’s ventilation system. In summer, it cannot cool because it doesn’t dehumidify, but in winter, it does dehumidify—even if the airflow is set to cold. (Of course, this is just a rough comparison.)

hampshire schrieb:

For most people, air conditioning is desirable. Those who appreciate nature, fresh air, and the scents of garden, forest, and meadow usually find other ways instead of retreating into tightly sealed buildings during summer and winter.

It’s ironic. We build energy-efficient houses to reduce heating demand in winter. These buildings become increasingly airtight and highly insulated. Great, very low energy use in winter! But then we realize we can’t get the heat out in summer anymore. So we install air conditioning. What a great way to save energy. Of course, when it’s hot, the air conditioning can be powered by photovoltaic systems, which is a positive step for climate protection.

I find it completely reasonable when a homeowner considers comfortable indoor temperatures and sees an air conditioner as the only solution.

NaNa, according to this logic, I should be roasted in my house during summer. Don’t generalize. I haven’t missed having air conditioning during the last two summers, even though I live in an extremely well-insulated house. And I hate heat. It is also not pitch dark inside because of shading on our house.

A lot depends on where the houses are located.

Mycraft schrieb:

Yes, the main cost driver is the 5 indoor units. If you reduce that to just three, the costs are cut in half. (Of course, you could install only 3 units for $15K, no problem.)

However, if you think $15K is acceptable, then… go for it. I mean, it’s fine. With all 5 units, the house will naturally be comfortably cool. So, what’s the actual question? Whether it will be cool or whether you can save somewhere?

By the way, what is the wall construction? And what do you imagine when you say smart home?

The air is dehumidified and sinks down. The warm air flows in and is also dehumidified and cooled from all rooms as long as the doors remain open, until the set temperature is reached. Of course, multiple indoor units make this process faster and more effective.

No, that’s not how controlled residential ventilation works. It only dehumidifies the air in winter because that’s when there is an exchange between inside and outside air. In summer, when the indoor and outdoor air have roughly the same humidity levels, the controlled ventilation system doesn’t dehumidify anything.

The controlled ventilation system’s function is almost identical to a car’s ventilation system. You can’t cool in summer because nothing is dehumidified, but in winter it does dehumidify, even if the airflow is set to cold. (Sure, that’s just a very rough comparison).

At first, I thought $15,000 was quite a lot, but considering the points raised, it makes more sense given the expected benefits in summer!

The system should also be designed so that you don’t have to think about when to open or close which door to achieve the desired temperature in each room.

Currently, the smart home system planned is Busch&Jäger Free@Home. However, the air conditioning apparently doesn’t have to be integrated there, since it operates independently using room sensors, right?