Definition
Healthy Homes Ventilation Standard The Healthy Homes Ventilation Standard requires every habitable room to have at least one openable window (≥ 5% of the floor area), kitchens to have an extractor fan with a minimum airflow of 50 litres/second, and bathrooms to have an extractor fan with a minimum airflow of 25 L/s that vents to the outside. ALLWISE auto-calculates window ratios and verifies extractor fan airflow against product specs.
Compliance threshold
Window ≥ 5% floor area; kitchen 50 L/s; bathroom 25 L/s
How to comply — step by step
- 1
Measure every openable window
In each habitable room (bedrooms, living, dining), measure the openable portion of at least one window. Calculate area in m².
- 2
Calculate window-to-floor ratio
Divide window area by room floor area. The result must be ≥ 5% (0.05). For a 12m² bedroom, the window must be ≥ 0.6m² openable.
- 3
Verify kitchen extractor
Confirm a working extractor fan is installed in the kitchen with ≥ 50 L/s airflow. Check the product label or installation certificate.
- 4
Verify bathroom extractor
Confirm a working extractor fan in each bathroom/toilet with ≥ 25 L/s airflow, venting to outside (not into the ceiling cavity).
- 5
Photo-document each
Take photos showing the openable window, kitchen extractor label, and bathroom extractor label. ALLWISE EXIF-tags each photo.
Common ventilation failures
- Bedrooms with only skylights (not openable)
- Bathroom fan venting into ceiling cavity
- Extractor fan airflow below 25 L/s
- Window area below 5% of floor area
Frequently asked questions
Does every bedroom need an openable window?
Can a recirculating bathroom fan satisfy HHS?
Skip the manual calculation
Need an assessment for this standard?
Book a certified inspection.
ALLWISE auto-fills the ventilation check into every statutory pack based on the property address, room dimensions, and BRANZ climate zone. Court-defensible evidence in 11 minutes.