Ever lived under the roof? In our current rental apartment, it’s over 30 degrees in summer – even at night. In our new house, we have a west-facing orientation, 2m wide windows, and are in the attic. Therefore, the system will run in night mode at night during the peak of summer.
The new houses are well insulated – in both directions. Our bedroom is under the roof (so upper floor), southwest side (on my avatar, the upper left window). When we didn’t have shading this summer, the house was like a sauna. But as soon as the roller blinds were installed, the house became cooler (even though it had been heated up for weeks before) and we had pleasant, sleepable temperatures in the bedroom. I am convinced that this year, if shaded consistently from the start and the house doesn’t even heat up, it will be even more comfortable. With shading, we had quite pleasant temperatures in the house even during the biggest heat this year. At night, let the cool air in, then keep the windows closed and shade. We never had over 26° in the whole house, even though, as mentioned, it was heavily heated up before.
A somewhat gentler cooling method is with cold water pipes that run in spirals in the ceiling. But for you, it’s probably too late. They cool the ceiling to the temperature of the cold water, and the cooler air falls down. That means about 5° cooling without creating any draft. So it should be completely sufficient in the new houses.