(1) (a) Every habitable room shall have, for the admission of light and air, one or more fixture, such as windows, fan, lights, opening directly to the external air or into an open verandah, and of an aggregate area, inclusive of frames, of not less than 1/10th of floor areas.
Note (1): If a window is partly fixed and partly openable, only the latter area will be counted for the above purpose.
Note (2): No portion of a room shall be assumed to be lighted, if it is more than 7.5 m (25 ft) away from the door or window which is taken for calculation as ventilating that portion.
(b) Cross ventilation by means of windows shall be effected in at least one living room of a tenement either by means of windows in opposite walls, or if this is not possible or advisable, then, at least in the adjoining walls.
(2) In the case of mechanized light and ventilation, the standards shall be such as to give the same intensity of ventilation as is provided in sub-rules (1) and (3) and subject to the approval of the Authority, provided alternative arrangements to ventilating and lighting the room according to the standards laid down in sub-rules (1) and (3) have also been made.
(3) Bathrooms and water closets shall be provided with natural light and permanent ventilation by one of the following means:-
(a) windows having an area of not less than 10 per cent of the floor area and located in an exterior wall facing 56 THE KOLKATA GAZETTE, EXTRAORDINARY, FEBRUARY 14, 2007 [PART I ' a street alley yard or an airshaft whose dimension in the direction perpendicular to the window is not less than 1/3 of the height of the building on which the window is located subject to a maximum and a minimum limit of 6 m (20 ft) and 1 m (3 ft) respectively;
(b) skylights, the construction of which shall provide light and ventilation as required in clause (a);
(c) ventilation ducts, provided such ducts have 1.30 cm2 of area for each m2 (2 in2 of area for each ft2) of floor area with a minimum total area of 330 m2 (48 in2) and a least dimension of 9 cm (31/2 in). The vent register or grills to the duct shall be located in or next to the ceiling or. the ventilated space. A separate duct from each space or room shall run to and above the roof and shall be provided with a lowered vent stack:
Provided, however, that when an exhaust fan is used, the duct opening may be located in an outer wall.
(4) Stores Box Rooms and the like shall have at least half of the ventilation required for living rooms. Where such ventilation by apertures in walls is not possible or advisable, at least there shall be ventilation by means of a flue or chimney.
(5) Laundry and recreation rooms located above the basement shall be lighted by windows located in exterior walls having openings of not less than 10 per cent of the floor area.
(6) Every kitchen shall be ventilated according to the standards prescribed for habitable rooms near the ceiling as far as possible. Each kitchen shall be furnished with smokeless chullas subject to the following conditions:—
(i) smoke shall not come out during the time of firing and cooking;
(ii) each kitchen shall be provided with a separate chimney;
(iii) chimneys provided for smokeless chullas shall be made of suitable diameter;
(iv) suitable provision shall be made at the bottom of chimney for clearing.
(7) Every staircase shall be lighted and ventilated from an open air space of depth (measured horizontally) not less than,—
(i) 3 m (10 ft) in case of ground and one upper floor structure;
(ii) 4 m (15 ft) in case of ground and two upper floor structures;
(iii) 6 m (20 ft) in case of further higher structures:
Provided that the lighting area shall be not less than 1 m2 (10 sq. ft) per floor.
Note.—Every staircase shall be ventilated properly.