ᐅ Does it make sense to install an air conditioning system?

Two things: Air conditioning does not make you sick. However, if you overuse it and lower the humidity levels so much through extreme cooling that your mucous membranes dry out, this can make you more susceptible to viruses or bacteria. But you still have to catch a cold from somewhere.

And: I also like to ventilate. I need fresh air. But especially in recent weeks, ventilating here (in southern Germany) has caused high indoor humidity levels (>65%). At such levels, even a harmless 24°C (75°F) becomes uncomfortable, and you feel sticky with light activity. In these cases, I use the air conditioner on a low fan setting mainly to dehumidify. The temperature drops by only about one degree, but the 15-20% reduction in humidity makes a noticeable difference. Unfortunately, underfloor heating combined with cooling does not help in this regard.

In short: I would recommend air conditioning in new builds (and definitely in older buildings) below 500 meters (1,600 feet) above sea level. With a reasonably open layout, install a small 3.5 kW indoor unit near the highest point of the house, running at a low setting for as long as possible. This way, the house does not warm up in the first place, and for around 2,500 euros, you get a level of comfort you could never have imagined.

Mycraft schrieb:

The underfloor heating with cooling didn’t work well enough here, so after one year, split air conditioning units were installed in the house. (I would do the same again)

I am now considering equipping the whole house with this system. You don’t have to cool it down to refrigerator temperatures, so there’s no risk of catching a cold.

Do you have any pictures of it? Retrofitting later surely doesn’t look very appealing? Several units outside – and how did you run the pipes?

Illya-Berlin schrieb:

Unfortunately, we cannot really assess whether it is necessary for the rooms to get hot during such hot days as the past two weeks, or if they remain cool due to the construction of a single-family house.

Since you yourself are unsure, I would at most prepare for it. It depends on personal sensitivity and, of course, the house itself on how warm it gets. An air conditioning system is definitely not necessary in a massive new build with shading options, but it can certainly be comfortable.

Consistently shade windows (automatically, for example with external venetian blinds in living areas) and insulate the roof well, especially in townhouse-style houses. Proper photovoltaic panels on the roof also provide additional shading.

Last summer, during two weeks of heat, the indoor temperature was a maximum of 25–26°C (77–79°F) in our house (pitched roof, only 20cm (8 inches) of mineral wool insulation, no photovoltaic system yet). I still found this pleasantly cool when it was hot outside. In the insulated, unoccupied attic, temperatures reached about 30°C (86°F). A massive house has thermal inertia; it takes days to heat up and also a long time to cool down once the outdoor temperature drops again. We experimented with cooling via an air-to-water heat pump; it was comfortable and helped remove heat faster from the house than the outdoor temperature dropped.

Leo schrieb:

Do you have any pictures? Retrofitting afterwards probably looks unattractive, right? Multiple outdoor units and how did you install the piping?

Sure, retrofitting generally looks worse. But no matter how you do it, air conditioning systems on single-family houses almost always look out of place. However, you can hide the piping very well inside the walls before the house is built and prepare everything accordingly. That way, later on, everything can be connected more or less plug & play.

I have one outdoor unit and three indoor units. I was able to route the pipes somewhat invisibly afterwards. In the (cold) attic, they run openly, then go down inside the insulation to the utility room (HAR), and from there, surface-mounted but more or less neatly, to the outdoor unit.

If I had known better from the start, I would have had the piping installed inside the walls. That way, for example, I wouldn’t now need condensate pumps at the indoor units.

Here, daytime temperatures have been around 30°C (86°F) or higher for days, with nighttime temperatures around 20°C (68°F). In our KFW55 monolithic house without any shading, the indoor temperature is about 22°C (72°F).

This is very comfortable, so depending on the construction method, an air conditioning system might not be necessary. However, it could be worth considering for the bedrooms, since in the attic they reach about 23°C (73°F), which is actually too warm in the summer.

Bookstar schrieb:

Here, daytime temperatures have been 30°C (86°F) or higher for days, with nights around 20°C (68°F). In our KfW55 house, built monolithically without shading, the indoor temperature is about 22°C (72°F).

Jealous. Even in winter, our living room quickly warms up to 25°C (77°F) or more thanks to large south-facing windows.