G4/AS1: Ventilation

G4 VENTILATION ACCEPTABLE SOLUTION G4/AS1 Spaces within buildings a) providing from the other habitable space to outside, openable windows and/or other openings of net openable area of no less than 5% of the combined floor area of the combined habitable spaces; and b) providing high and low level trickle ventilators located on the external wall (see Paragraph 2.2.2.5 for trickle ventilators), sized according to the combined floor area; and c) providing an area of permanent opening between the two spaces of no less than 5% of the combined floor area of the habitable spaces; and d) having a combined distance of the habitable spaces, measured between the external wall and furthest opposing wall, of less than 6 metres. COMMENT: Habitable spaces must not be naturally ventilated via an adjacent space that is a bathroom, kitchen, toilet or laundry. 2.2.2.5 Trickle ventilators are devices that have an opening to the outside. Trickle ventilators shall: a) have an opening of no less than 2000 mm2 equivalent aerodynamic area; and b) be located to minimise draughts; and c) be secured to keep pests and insects out; and d) have acoustic attenuation, if required by Building Code clause G6 Airborne and Impact Sound; and e) be controllable and closable in all conditioned spaces; and f) be installed in household units, providing they do not contain mechanical supply ventilation; and g) have the equivalent aerodynamic area, based on the number of occupants, for the space as given in Table 2.2.2.5A and Table 2.2.2.5B; and h) have, where high and low level trickle ventilators are required, the high and low level trickle ventilators of approximately the same equivalent aerodynamic area and separated by a minimum of 1 metre. High level trickle ventilators are located in the top half of the wall. Low level trickle ventilators are located in the bottom half of the wall. COMMENT: There are a range of trickle ventilators, sometime called background ventilators, on the market. Table 2.2.2.5A: Number of occupants for the space Paragraph 2.2.2.5 g) Household unit type Number of people Studio 2 people 1 bedroom 2 people 2 bedroom 3 people Greater than 2 bedrooms 3 people plus 1 person for every bedroom after 2 Table 2.2.2.5B: Total required equivalent aerodynamic area for the space (mm2) Paragraph 2.2.2.5 g) Ventilator locations 1 occupant 2 occupants 3 occupants 4 occupants 5 occupants High and low level 4000 mm2 8000 mm2 12000 mm2 6000 mm2 20000 mm2 High level only 3000 mm2 6000 mm2 9000 mm2 12000 mm2 15000 mm2 MINISTRY OF BUSINESS, INNOVATION AND EMPLOYMENT 28 JULY 2025 Page 10