(1) Where it is proposed to provide mechanical ventilation to any building or part thereof, details of the ventilation system concerned shall be set out in working-drawings, and shall be submitted to the local authority for its approval.

(2) Details of working-drawings shall include the maximum quantity of outside air per minute which such mechanical ventilation system can supply continuously to all the rooms to be ventilated, together with the number of persons for whose simultaneous use such rooms are authorized or intended (herein-after referred to as the “occupancy” of such rooms).

(3) All metal parts of ducts and machinery associated with any mechanical ventilation system shall be electrically bounded to earth.

(4) Any system providing mechanical ventilation in a building shall be maintained in working order, so as to deliver the quantity of air required by sub-section (5).

(5) Every mechanical ventilation system shall—

a) In the case of occupied areas, supply outside or outside-and-recirculated air—

i) Where the occupancy is known, at the rate and in the proportions specified in Table I;

ii. Where the occupancy is unknown, at a rete of 6 cubic meters per hour per square meter of floor area of each room in the proportions specified in Table I;

b) In the case of services areas, supply outside air or extract air at the rates and by the means specified in Table II.

TABLE I

TABBLE II

(6) Air may be recirculated only in a mechanical ventilation system and in accordance with the following provisions—

a) Outside air shall be added to the recirculated air at a rate not less than that required by subsection (5);

b) Recirculation of air in a factory, laboratory, workshop or room shall be permitted only if the local authority is satisfied that the recirculated air is sufficiently free from bacteria, dust, fumes, vapours, mists or gases as to be harmless to the occupants of such factory, laboratory, workshop or room;

c) Air shall not be recirculated from passage-ways, stairways, kitchens, water-closets, urinals, toilets, bath-rooms, lobbies, rooms containing soil-water fittings, rest-rooms or garages:

Provided that it shall be permissible to recirculate air from passageways designed as return airways;

d) Except as may be approved by the Ministry of Health, air extracted from hospital operating-theatres or from any room in an infectious diseases hospital shall not be recirculated.

(7) Quantities of air mechanically supplied or extracted from a room or building shall be measured in or at the openings to the ducts conveying the air.

(8) The size and position of the ventilation-openings in the walls of rooms ventilated by mechanical ventilation shall be such that—

a) When air is being supplied by mechanical ventilation systems, its velocity, as measured with a velometer or other approved apparatus at six different points selected at random, being not less than 1,2 meters from the ventilation-openings and at heights varying from 750 millimeters to 2,1 meters above the floor, should not be less than 9 meters per minute, and not greater than 18 meters per minute;

b) No portion of any air-intake opening outside a building shall be at a height of less than 3 meters above the outside ground-level, unless otherwise permitted by the local authority. The positions of all such air-intake openings and of all discharge-points shall be subject to the approval of the local authority, which shall have regard to the possibility of any source of contamination which may be adjacent to any such air-intakes openings or which may be caused by any discharge-points, and to any objection-able noise to owners of adjacent buildings;

c) Where air is exhausted above a pavement of a street, no portion of the air-exhaust opening outside a building shall be at a height of less than 3 metres above the level of such pavement.

(9) Every air-supply system with a capacity of 25 000 cubic meters per hour or larger, or such a system supplying a building of more than three storeys, shall be capable of being automatically and manually stopped in case of fire. The position of the manual stopping-device shall be determined by the local authority.

(10) Any exhaust system from which the air exhausted can be wholly or partially returned to the building by a supply system, shall be arranged to change over automatically to full exhaust when fire is detected by approved automatic means.