You may have heard of Class A, Class B and Class C louvres. But what do these classifications mean, and are they important?
WIn a nutshell:
- There are two main types of louvres – screening louvres and performance louvres
- Louvres that are designed to hide plant and machinery don’t need to be tested
- Performance louvres are tested and classified under BS EN 13030:2001
- The BSRIA has a specialist weather louvre test facility that simulates real-life operating conditions
- The BSRIA classifies performance louvres for water penetration and airflow in line with BS guidelines
- Class A (of A-D) louvres allow the least water to get through
- Class 1 (of 1-4) louvres have the least resistance to air flow
Before we answer the question, it’s important to know that there are two main types of louvres: screening louvres and performance louvres.
The first type, as the name suggests, are designed to hide unsightly plant and machinery from view. They may provide some ventilation and weather protection but they don’t need to be tested.
Performance louvres are ventilation products. They’re designed for two apparently contradictory functions: to keep wind-driven rain (and dirt, pollution and pests) out of a building, and to allow maximum airflow.
A solid barrier will provide complete protection but no airflow; a hole in the wall will maximise airflow but provide no protection. What’s more, the airflow may not always be inwards. In a car park, for example, louvres will help disperse exhaust fumes.
In other words, it’s complicated. To help you decide what’s best for your project, louvres are tested and classified under BS EN 13030:2001.
Who carries out the testing?
The BSRIA (Building Services Research and Information Association) is a global organisation that helps its members improve the quality of their products and services. It has a specialist weather louvre test facility in the UK that simulates real-life operating conditions, and classifies the products in line with the BS guidelines.
During testing, louvres are assessed for their effectiveness at preventing rain ingress and their ability to let air pass through. Depending on the project, one feature might be more important than the other.
Part 1 - Water penetration
The louvres have water blown against them. Class A allows the least water to get through – blocking more than 99%. Class B louvres will offer protection of between 95% and 98.9%. Anything below 80% will be Class D.
Part 2 - Airflow
Here, we’re measuring aerodynamic qualities, and looking for the least resistance to air. Testing measures the Discharge Loss Coefficient (DLC) but in everyday terms, Class 1 is excellent, Class 2 is very good, Class 3 good and Class 4 fair.
So, what’s right for you? Probably a compromise, so before jumping straight in and specifying Class A or Class 1, it’s always best to discuss your requirements with a louvre specialist.
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