All main use areas of buildings and construction projects must have adequate natural lighting and air cooling, direct or indirect.
It is allowed for the main use areas of special buildings and construction projects not to have natural lighting, when natural lighting does not serve their function, and not to have natural ventilation, when they have artificial ventilation that is sufficient.
In any case, direct natural lighting and ventilation must have the main use areas of the houses and the bedrooms of the temporary accommodation buildings.
The following areas must also have direct natural lighting and ventilation, provided they are not exempt from the natural lighting and ventilation requirement:
- classrooms, with the exception of auditoriums
- sports areas
- restaurants, patisseries, cafes and any other place where it is served food or edible preparations or beverages.
- nursing or care wards and the day care areas of the health and social welfare buildings.
- laboratories of all buildings
- accommodation rooms of under trials or convicts in prison buildings
- offices of all buildings, unless they are single floors using offices in a free layout, in which case indirect natural lighting and ventilation is allowed
- kitchens
- pharmacies
- library reading rooms
- main workplaces of industries and crafts.
- staff rest areas of all buildings.
The spaces are considered to have sufficient direct natural lighting, when the area of these openings does not fall short of 10% of the net area of the space.
The spaces are considered to have sufficient direct natural ventilation, when the area of these openings is not less than 5% of the net area of the space.