What elements do you need to consider when specifying a weather louvre?

A weather louvre is a passive device, essentially a grille fixed over an opening, designed to let air through and keep water out. It is designed to perform both these functions simultaneously, and its suitability for a particular application is determined by how effectively it achieves these functions in combination.

Failure to understand and clearly express the performance requirement at the design or procurement stage increases the risk of the product not being fit for purpose. The end user may experience unwanted water penetration or wasted energy.

To achieve optimum performance, system designers and specifiers of weather louvres must have an appreciation of:
•    How to understand weather louvre requirements
•    How to minimise whole-life costs through system design and louvre selection
•    Which terms to use to ensure that performance data are consistently stated when sourcing products from suppliers
•    How to minimise risks associated with overstated performance claims

Performance Testing

The standard performance tests for weather louvres are described in BS EN 13030 and BS EN 13181. The test methods are designed to simulate real-life operating conditions the louvre will undergo when installed.  The rejection performance can be established for a range of ventilation rates while subjected to windblown rain or sand.
BSRIA operates a specialist weather louvre test facility, which offers clients independent performance testing of weather louvres to these standards.

Specifying a Weather Louvre

To specify a weather louvre usefully requires the following elements:

•    Understanding of the required volume flow rate, louvre face area and subsequent face velocity
•    Understanding of the permissible water penetration for the application, based on the classes provided by the standard test (A-D)
•    Understanding of the standard test classes for discharge or entry loss coefficient (1-4) and that a higher Cd means lower energy usage.

It must be noted that other factors can affect the performance of a weather louvre which is not accounted for by the standard test.
If you are looking for further information visit http://www.bsria.co.uk where you can download BSRIA’s Weather Louvre Specification Guide (BG 36/2012) for FREE or for louvre testing enquiries either contact 01772 754381 or email: bsrianorth@bsria.co.uk

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