Navigating the New AS 4740:2025 – What You Need to Know
Navigating the New AS 4740:2025
What You Need to Know
At CS, we’re all about high-performance ventilation solutions, particularly Type 1 Ventilators – Fixed Grilles and Louvre Panels. These elements are essential for creating efficient, sustainable, and visually refined spaces.
So of course, we were thrilled to see that after 25 years, Standards Australia has introduced AS 4740:2025, replacing AS/NZS 4740:2000. In 2016, Standards Australia reconfirmed the 2000 version with no changes. This recent update brings important refinements and new technical specifications that will help shape the future of ventilation design.
Why This Matters
As a leader in standards development, Standards Australia plays a crucial role in maintaining high-quality manufacturing and product performance. The updates in AS 4740:2025 bring a new level of precision, ensuring better classification, testing, and overall product reliability.
Here’s a quick look at the most important changes:
1. Improved Rain Resistance Classification
The standard now offers a clearer definition for Class A ventilators. Previously, these were classified as having 1 to 0.99% rain resistance. The 2025 update refines this to 100%–99% effectiveness, eliminating ambiguity and making product classification more straightforward.
2. New Definitions - Core Area and Core Velocity
For the first time, AS 4740:2025 formally defines two key measurements:
- Core Area – The minimum Height × Width of a ventilator’s front opening (excluding blades).
- Core Velocity – The airflow rate divided by the core area.
These updates ensure a more standardised approach to ventilator performance and design assessments.
3. Detailed Throat Area Definition
The AS 4740:2025 defines and further clarifies the ‘throat area’ as the total open area available for airflow, calculated as the sum of the areas between the head and top blade, the sill and bottom blade, and between each adjacent louvre blades.
This update helps provide further clarity on understanding throat area.
4. Expanded Rain Resistance Testing
A new “Extended Range” testing method has been introduced, allowing for more rigorous assessments under high-intensity wind and rain conditions. This method aligns with the AMCA-500-L International Standard. The performance improvement is substantial:
- Wind resistance increased by 70%
- Rain intensity increased by 170%
5. Enhanced Testing & Measurement Accuracy
The updated standard refines airflow and pressure measurement techniques to align with modern testing capabilities. Additionally, aerodynamic performance assessments now follow a more precise, equation-based approach for consistency and accuracy.
Looking Beyond AS 4740:2025
While AS 4740:2025 establishes an important benchmark for Type 1 Ventilators, it is not the only independent testing standard out there. Organisations such as the Air Movement and Control Association (AMCA) conduct rigorous testing, verify datasheets, and publish results on their website, ensuring a high level of transparency.
At Construction Specialties, we take quality seriously. That’s why we are proud to be the only Australian manufacturer producing louvres that have been independently tested and certified by AMCA. This commitment to superior performance ensures that our solutions meet – and exceed – both local and international standards.
What’s Next?
AS 4740:2025 raises the bar for natural ventilation, driving innovation and improved product performance. As the industry adapts to these changes, we look forward to seeing how ventilation solutions evolve to meet these higher standards.
Interested in cutting-edge ventilation solutions? Explore our storm-resistant louvre range to see how we’re leading the way.
Book your CPD with CS to enhance your knowledge of the new AS 4740 and stay ahead in ventilation design.