Understanding the NCC 2022 Ventilation Requirements for Buildings Under 5 Air Changes Per Hour
NCC 2022 Ventilation Requirements for Homes Under 5 ACH
The National Construction Code (NCC) 2022 introduced pivotal changes to ventilation requirements in Australia, particularly for buildings with less than 5 air changes per hour (ACH). This marks a significant step towards improved indoor air quality and energy efficiency in modern buildings.
However, from the perspective of a specialist ventilation business, these changes represent a starting point — not the end goal. While the NCC 2022 establishes a minimum benchmark, there is still a long way to go to ensure genuinely healthy indoor air quality and mould-free homes for all occupants.
Why Ventilation Matters More Than Ever
Effective ventilation plays a critical role in maintaining indoor air quality, controlling humidity, and protecting occupant health and comfort. In buildings with less than 5 ACH, natural air exchange is limited, meaning stale air, moisture, and pollutants are far more likely to accumulate.
In these homes, mechanical ventilation is no longer optional — it is essential.
NCC 2022 Ventilation Requirements Explained
The NCC 2022 places a stronger emphasis on mechanical ventilation for buildings with low natural air change rates. These requirements are outlined in:
- Volume 1 Part J1V4 — for Class 2 to 9 buildings
- Volume 2 Part H6V3 — for Class 1 and 10 buildings
For the first time, the NCC introduces a clear method for calculating minimum ventilation airflow rates in residential buildings, providing a measurable compliance pathway.
How to Calculate NCC 2022 Minimum Airflow Requirements
A key component of the NCC 2022 is a new formula used to determine the minimum airflow required for a dwelling. This calculation considers both the size of the home and the number of bedrooms:
Airflow (L/s) = 0.05 × Area (m²) + 3.5 × (Number of Bedrooms + 1)
Where:
- Area is the total floor area of the dwelling
- Number of Bedrooms refers to the total bedrooms in the home
This formula determines the minimum volume of fresh air (in litres per second) that must be supplied to the dwelling.
Example Calculation
As part of a recent quotation, we assessed a residential building with:
- Total floor area: 210 m²
- Number of bedrooms: 4
Applying the NCC 2022 formula:
Airflow = 0.05 × 210 + 3.5 × (4 + 1) = 28 L/s
This equates to a minimum airflow requirement of 100.8 m³/h.
NCC 2022 Minimum Ventilation Airflow Calculator (Homes under 5 ACH)
Use this calculator to estimate the minimum ventilation rate required under NCC 2022 for homes with airtightness under 5 ACH@50Pa, using the formula:
Airflow (L/s) = 0.05 × Area (m²) + 3.5 × (Number of Bedrooms + 1)
Results
System Type Recommendations
Based on the minimum airflow requirement and number of bedrooms, the following system types may be appropriate. These recommendations go beyond minimum compliance and consider comfort, coverage, and long-term performance.
Compliance and Practical Implementation
To comply with NCC 2022, builders and homeowners must install mechanical ventilation systems capable of meeting these calculated airflow rates. These systems must also align with broader NCC objectives around energy efficiency and sustainability.
On paper, compliance may appear straightforward. In practice, however, meeting minimum airflow targets does not necessarily guarantee good indoor air quality throughout the entire home.
What This Means for Ventilation Businesses
For businesses like Fresh Ventilation, the NCC 2022 changes are a welcome step in the right direction. Ventilation is finally part of the conversation — something that has historically been overlooked during most builds.
However, as the example above demonstrates, achieving compliance at 100.8 m³/h highlights just how low the minimum benchmark currently is for many modern homes.
What We Recommended for High Indoor Air Quality
Recently, Fresh Ventilation provided a proposal for a multi-level residence in Canberra, designed with long-term indoor air quality in mind rather than minimum compliance alone.
Fresh air supply was provided to:
- 4 bedrooms
- Rumpus room
- Study
- Living room
- Dining room
Stale air extraction was taken from:
- 3 bathrooms
- Kitchen
- Laundry
- Pantry
Our design centred around a centralised heat recovery ventilation (HRV) system capable of delivering up to 350 m³/h. Fresh air was supplied to eight locations, with stale air extracted from six opposing areas to ensure whole-home air movement.
The system was designed to perform effectively even when doors were closed and different areas of the home were isolated — a common real-world scenario.
What the Homeowner Needed to Do to Comply with NCC 2022
The homeowner’s primary objective was strict compliance with NCC 2022. Based on the calculated requirement of 100.8 m³/h, they opted for a simplified solution — a single decentralised ventilation unit installed in one room of the home.
Why This Matters
While this approach technically satisfies NCC 2022, it has clear limitations — particularly in a multi-level home. A decentralised system operating in a single location cannot reliably ventilate bedrooms, living areas, and other isolated spaces when doors are closed.
This is especially concerning in sleeping areas, where occupants spend long periods of time and indoor air quality has a direct impact on health and wellbeing.
Our experience shows that for most modern homes, a whole-home ventilation approach delivers significantly better outcomes in comfort, humidity control, and air quality — even though it exceeds minimum code requirements.
Conclusion
The NCC 2022 represents a major step forward in Australian building standards by formally recognising the importance of ventilation in modern construction. For the ventilation industry, it reinforces the need to stay informed, adaptable, and proactive.
However, meeting the NCC 2022 requirements should be viewed as a baseline — not a complete solution. There is substantial opportunity to go beyond minimum compliance through better ventilation design and advanced systems that deliver healthier, more resilient indoor environments.
Poor ventilation and uncontrolled humidity are key contributors to mould growth, which can have serious health implications. By exceeding minimum standards and implementing comprehensive ventilation strategies, we can better manage moisture, reduce mould risk, and significantly improve indoor air quality.
In essence, while the NCC 2022 lays the groundwork, ventilation professionals like Fresh Ventilation have an important role to play in lifting the standard of living and wellbeing in homes and workplaces across Australia.
Key Takeaway
The National Construction Code (NCC) 2022 sets the minimum ventilation requirements for buildings with airtightness below 5 air changes per hour. It establishes a baseline airflow rate that all compliant mechanical ventilation systems must meet.
Meeting the NCC minimum does not guarantee healthy indoor air quality on its own. The Code specifies what ventilation is required, not how it should be designed or distributed throughout a home.
Coverage and thoughtful system design are essential if you want effective ventilation that controls humidity, removes pollutants and significantly reduces the risk of mould.
A single extraction fan — especially in a large, multi-storey home with multiple bedrooms — will not achieve good results on its own, even if it technically meets the minimum airflow requirement.
Well-designed ventilation systems deliver healthy indoor environments by ensuring fresh air reaches all key living spaces and stale air is extracted where it matters most, not just in one isolated area.