Первичным источником естественного

Первичным источником естественного освещения является солнце. Естественная освещенность внутри здания значительно меньше наружной освещенности. Естественное освещение помещений может быть боковое – через окна в наружных стенах, верхнее – через – световые фонари и проемы в покрытии, а так же в местах перепадов высот смежных пролетов здания, комбинированное – верхнее освещение плюс боковое.
Электрическое освещение необходимо для проведения работ в темное время суток или в местах без достаточно естественного освещения. Выбор источника света зависит от характера работы, условий среды, размеров помещений. Используют лампы накаливания, люминесцентные лампы. Для освещения применяют осветительные приборы ближнего и дальнего действия.

Результаты (английский) 1:

The primary source of natural light is the Sun. Natural illumination inside the building, much less external light. Natural lighting can be side-through Windows in the exterior walls, the top-through-skylights and openings, as well as in the field of differential heights of adjacent spans buildings, combined-top lighting plus side.Electric lighting is necessary for work in the dark or in areas without enough natural lighting. Selection of light source depends on the nature of the work conditions Wednesday, sizes of premises. Use incandescent lamps, fluorescent lamps. Used for lighting the lamps of near and distant action.

Результаты (английский) 2:

The primary source of natural light is the sun. Natural lighting inside the building significantly less ambient light. The natural lighting of premises can be a side - through the windows in the outer walls, the top - through - skylights and openings in the coating, as well as in places of height differences of adjacent spans of the building, combined - overhead lighting plus side.
The electric lighting is required for work in the dark time of the day or in areas without sufficient natural light. The choice of light source depends on the nature of the work, environmental conditions, size of the room. Use incandescent lamps, fluorescent lamps. For illumination use lights near and long range.

Результаты (английский) 3:

the primary source of natural light is the sun. natural light inside the building is significantly smaller than the ambient illuminance. natural lighting facilities may be side - through windows in the exterior walls, top - through - lighting lanterns and gaps in coverage, as well as in the field of related building heights were better, the combined - top lighting plus side.electric lighting needed for work in the dark, or in the field without sufficient natural lighting. the choice of light source depends on the nature of work, environment pollution, the size of the space. use incandescent lamps, fluorescent lamps. lighting apparatus for lighting using the middle and long-range.