G4/AS1: Ventilation

G4 VENTILATION ACCEPTABLE SOLUTION G4/AS1 Spaces within buildings 2.3.3.2 Spaces in which mechanical ventilation is used to remove or collect contaminants shall be maintained at negative pressure relative to other spaces in the building. COMMENT: Negative pressure reduces the likelihood of contaminants being spread to other spaces. 2.4 Combined natural ventilation and mechanical ventilation 2.4.1 Household units and accommodation units with one external wall 2.4.1.1 This section specifies the combined natural and mechanical ventilation requirements for both household units and accommodation units, with one external wall, such as those often found in apartments, hotels and motels. 2.4.1.2 Habitable spaces will be naturally ventilated; and kitchens, bathrooms, toilets and laundries will be ventilated by continuous or intermittent mechanical extract ventilation (refer to Section 2.3). 2.4.2 Combined natural ventilation with continuous or intermittent mechanical ventilation 2.4.2.1 Habitable spaces with one external wall and a permanent opening to a kitchen, bathroom, toilet or laundry, within which a continuous or intermittent mechanical extract system is installed, must be ventilated by: a) integrating high level trickle ventilators, located within the external wall or building elements that are integrated within the external wall (see Paragraph 2.2.2.5 for trickle ventilators); and b) having a net openable area of windows and/ or other openings to the outside of no less than 5% of the floor area; and c) having the kitchen, bathroom, toilet, or laundry door undercut by 20 mm; and d) having a maximum dimension between the external wall and the furthest internal opposing wall, when measured across the combined habitable space and the kitchen, bathroom, toilet, or laundry, of i) less than 10 metres for continuous mechanical extract systems, or ii) less than 6 metres for intermittent mechanical extract systems. COMMENT: If Paragraphs 2.4.2.1(d)(i) and (ii) both apply, then ventilation shall be achieved by complying with Paragraph 2.4.2.1(d)(ii). MINISTRY OF BUSINESS, INNOVATION AND EMPLOYMENT 28 JULY 2025 Page 12