Weather louvres can combat and complement the effects of climate change

[edit] Introduction

When it comes to the efficient operation of a building, even the seemingly small decisions can have a big consequence. For example, what elements do you need to consider when specifying a weather louvre? BSRIA North’s expert, louvre-testing facilities offer a solution.

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 concurrently and its suitability for a specific application is established by how effectively it achieves these functions in combination.

[edit] June Davis, Business Manager, BSRIA North, said:

“Weather louvres are big business and BSRIA can offer many hints and tips. 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. This certainly isn’t a green approach. And, just as crucially for BSRIA members, does it save money?”

[edit] 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, and
• Performance testing

The standard performance tests for weather louvres are described in BS EN 13030:2001 Ventilation for Buildings -Terminals - Performance testing of louvres subjected to simulated rain and BS EN 13181:2001 Ventilation for Buildings - Terminals - Performance testing of louvres subject to simulated sand.

June Davis continued:

“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 members and clients alike independent performance testing of weather louvres to these standards.

Indeed, it’s a niche and unique operation and facility. We are often asked questions by members about louvres and, specifically, increasing the quantity of the air flow through the louvre.”

[edit] 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), and
• Understanding of the standard test classes for discharge or entry loss coefficient (1-4) and that a higher Cd means lower energy usage.

June Davis added:

“It must, however, be mentioned that other factors can affect the running and performance of a weather louvre which are not accounted for by the standard test.”

If you are looking for further information visit 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 754 381 or email: uk [email protected]uk

[edit] About this article

This article was provided by BSRIA and appeared origianlly on its website in June 2019.

BSRIA is a non-profit distributing, member-based association providing specialist services in construction and building services. More information at www.bsria.co.uk.

Other articles by BSRIA can be seen here.

[edit] Related articles on Designing Buildings Wiki

• Air infiltration testing.
• Approved Document F.
• BREEAM Potential for natural ventilation.
• BREEAM Visual comfort Glare control.
• Building services.
• Condensation.
• Curtain wall systems.
• Daylight lighting systems.
• Humidity.
• Interstitial condensation.
• Louvre (louver).
• Louvre specifications.
• Mechanical ventilation.
• Natural ventilation.
• Passive building design.
• Rainscreen
• Solar shading.
• Stack effect.
• Thermal comfort.
• Ventilation.

--BSRIA