Newly built apartment (KfW-55) cannot be cooled, always at least 25 °

The houses are insulated. This means that the phase shift is changed. If the heat is stored in the substance, it takes time to get it out again. Especially with two-shell masonry or [WDVS]. Monolithic potentially (!) cools down faster. In the case of the example with the 20cm concrete... There is simply so much mass present that it first needs to be cooled down.

I also believe that several components come together, so that you can only compare old buildings with new buildings to a limited extent.

I live in the commuter belt of a big city. When we drive into the city, there can definitely be a temperature difference of 5-10°. Especially in summer, a lot of heat is absorbed and consumed by nature in rural areas, while the concrete blocks in the big city act as real heat storage units. Assuming we do not compare old buildings in the countryside with new buildings in the city, the plots in new housing developments are still often smaller than before or are being densified, and there are no trees yet, terraces are larger... let's better not talk about the "stone front gardens." All this leads to the ambient air already being significantly warmer, similar to the big city. We have a beige large terrace on the west side made of 8 cm thick terrace slabs. Although it is light-colored, in summer you could hardly sit on the terrace from midday without overheating. The living room behind it heated up extremely despite closed shutters. Since we have a roof with an awning, it is much more pleasant on the terrace and thus also in the living room behind it.

On the ground floor, we hardly have temperature problems in summer. The tiles on the ground floor also contribute to a good feeling. On the upper floor, we ventilate properly at night. That actually gets us through the summer well. However, this only works as long as it cools down at night and does not stay above 25° at night as in the big city.

KfW70 with monolithic 36.5cm and double-glazed windows: actually consistently 23 degrees in the house. When it was often over 30 degrees, it was sometimes 25 degrees in the living room because the terrace door was frequently opened. Otherwise, at night at least one window tilted open and early in the morning ventilating at 17-19 degrees, then closing the shutters on the south and west sides during the day. I know why I didn’t build KfW55 or 40... so a plastic house with ventilation system.

Passive house with ventilation system we never had 25 degrees in the house. Usually around 20-23 degrees without air conditioning. So that can’t be the reason. Shading and cool air at night. This year we only had 2 or 3 nights with temperatures over 20 degrees. How much and how long the air cools down at night depends on other factors. You live in a developed neighborhood with relatively lots of greenery. Your garden no longer releases heat into the air, whereas a parking lot would still radiate heat for a long time.

Passive house with ventilation system 25 degrees we have never had in the house. Mostly around 20-23 degrees without air conditioning.
So it can't be because of that.

Shading and cool air at night. This year we only had 2 or 3 nights with temperatures over 20 degrees.
How much and how long the air cools down at night depends on other factors. You live in a developed settlement with relatively a lot of greenery. Your garden no longer emits heat into the air, whereas a parking lot would radiate heat for a long time.

So what is the reason that you seriously have 20 degrees maximum 23 and I 25? Are we talking about the ground floor or upper floor? Do you open the windows at night then or how exactly does that work?

So what is the reason that you seriously have 20 degrees max 23 and I 25? Are we talking about the ground floor or the upper floor? Do you then have the windows open at night or how exactly does that work?

Don't believe everything. No one here has 20 degrees after weeks of drought, sun and blue sky... except at 3 a.m. at the open window measured

Don't believe everything. No one here has 20 degrees after weeks of drought, sun and blue sky… except measured at 3 a.m. at the open window

I think the temperatures outside were meant. With good ventilation, you can also get cool temperatures inside.