## 3 Results and Discussion
In apartments A3, A8, and A9, the number of total hours above the first level of the internal environment was very low and did not exceed 10. The first of the dwellings were located on the tenth storey; the other two were on the third. They had a rather big floor area, resulting in one of the lowest internal gains and one of the lowest glazing-to-floor ratios (18.20%, 10.51%, and 13.06%, respectively). Their inhabitants preferred window shading and/or venting to avoid overheating:  
* In the A3, night ventilation was applied by half-opening the SSW windows and trickle ventilation of the NNE windows. During the day, SSW windows were closed and shaded, and the NNE ones were half-open. * In the A8, one of the windows in the living room (also functioning as a bedroom) was constantly cracked open, and the balcony doors were opened daily. In the study facing NNW, the window was closed, and the curtains were not used in any of the rooms. * In the A9, one of the windows facing NNE and one facing SSW were half-opened. The roller blinds in the living room that were connected to the bedroom were not closed during the day, instead, they were drawn in the afternoons for privacy. The owner declared no actions were taken during excessive heat. * Despite different strategies, the effects were very good, lowering the overheating hours to almost zero. The A4, A7, and A10 apartments showed a medium overheating level, with no more than 100 h exceeding the first level of the internal environment. The time of high internal temperature was 3.3% to 5.9% of the monitoring period, so it was probably not a long-lasting discomfort. The following precautions were taken to prevent the rooms from overheating:  
* In apartment A4, the first measure taken to lower the temperature was closing the windows and, in turn, shading. In the room facing north, one window was half-opened daily, and in the room facing south, the balcony doors were opened for ventilation purposes. The rest of the windows were in a trickle ventilation mode. Some of the windows facing south were shaded during the day, and the windows facing north were shaded only in the afternoon for privacy. * In apartment A7, two windows were cracked open during the day and opened later in the afternoon (they were closed in the living room with the bedroom and in the room). The windows in the main living area were permanently shaded, and in the kitchen and the room, silver reflective curtains were used. Despite these measures, the owner turned on mechanical cooling during heat waves, which probably helped him to restrict the overheating hours to 5.9% of the monitoring time--this need could be caused by the lowest heat transfer coefficient of the apartment outer shell, making it difficult to move the heat to the outside. * In apartment A10, the owners preferred opening windows to using internal shades; balcony doors were opened during the whole day, and two opposite windows were half-opened, supporting the airflow. Curtains and blinds were installed but not used, except for closing them when watching TV and for privacy. The most severe overheating was experienced in apartments A1 and A5, both in the uppermost floors. It covered 10.5% of the overheating time and was probably connected to the top-storey locations, little external shading, and specific usage patterns. A1's bedroom windows faced SSW and were not shaded by the installed roller blinds, and likewise, for the living room windows (except for watching TV in the afternoons). The two rooms on that side of the dwelling were also rarely ventilated; one window was cracked open in the kitchen, and in the room, and it was not enough to ensure air exchange. During heat waves, mechanical cooling was turned on for 3 h in the afternoon to keep the internal temperature at an acceptable level, and in the living room, a portable fan was used. The advantages of the highest heat transfer coefficient were counterbalanced here by the solar absorption on the dark roof surface.