The insolation of premises in residential, public buildings, and adjacent areas regulates the flow of natural ultraviolet radiation and is an important factor that must be taken into account in the design of urban development. It helps tolimit the spread of viral and bacterial diseases transmitted both by airborne aerosol droplets and through public surfaces of premises. The article analyzes the current state of standardization and calculation of the sun duration in national and foreign standards. It is shown that ultravioletlight enters rooms through modern energy-saving glazing. It is concluded that it is necessary to preserve this factor in ensuring the safety of buildings and structures. Keywords: sun duration (insolation), insolation graph, solar map, building density.