The presented study deals with the space located in the attic of an older building after reconstruction. Originally, the attic space was not used, as it did not have sufficient headroom. The reconstruction was designed in such a way that the entire original pitched roof was gradually raised by 1.2 meters in parts, creating a full-fledged space under the pitched pitched roof. The visual connection of the interior space with the exterior was ensured by continuous strips of vertical windows around the perimeter of the building, each window measuring 600x600 mm. The space is also illuminated by several skylights at roof level, which, although they ensure sufficient penetration of daylight from above into the interior, at the same time allow for considerably unpleasant overheating. The task was to find a way to optimize the size of transparent surfaces and determine the accumulation of building structures in order to achieve an acceptable cumulative effect of daylight and overheating, i.e., permissible increase in indoor air temperature in summer. It means trying to theoretically design a suitable and comfortable interior space in the attic in an already existing building.

The classroom space located in the attic of an old building is the subject of this study. The building was renovated and new spaces were created in the unused attic to expand classrooms. The original space under the sloping roof was not used because its internal headroom was not suitable. During the restoration, the entire original truss was raised gradually (in parts) by 1.2 m. This created a space with an entire area that can be used for classrooms. Continuous strips of vertical windows measuring 860/600 mm were installed in the space which enable a visual connection between the interior space and the exterior. At roof level, there are also two rows of skylights above each other which ensure enough daylight is present but create unpleasant overheating in the summer. The purpose of this study is to find a way to optimize the shading of transparent surfaces and the heat accumulation of building structures in order to achieve suitable interior conditions in the attic. This task was achieved by shading the windows in the attic. Shaded windows decrease illumination by 82% compared to unshaded ones. The percentage decrease in illumination is more significant than the decrease in the maximum temperature due to overheating. Additionally, the maximum temperature in the attic drops by only 31% if vertical and skylight windows are shaded with external blinds compared to unshaded windows. The minimum air temperature reached in the attic also drops by 26%. In order for users in the attic space to feel comfortable, it is necessary to use HVAC equipment in addition to the design of suitably built structures and window shading.

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