Throughout the years, quantifying the performance of rainproof ventilation louvre systems has always been  problematic. This is due to the escalating standards for practical applications as well as the non-existence of comprehensive application technology guidelines for designers. The HEVAC standard for “Laboratory Experiments and Grading Levels of Rainproof Ventilation Louvres under Simulated Environmental Conditions” has provided a useful classification method. However, the responsibilities for recommending classification methods of special applications remain with the designers and experts. Hence, the purpose of this guide is to contribute modestly to assisting designers and experts in selecting the most effective performance classification for rainproof ventilation louvres deployed in special applications.

Experimental Standard: British rainproof ventilation louvre system maker joined hands with HEVAC and BSRIA to invent an experimental standard aimed at assisting designers in adapting different classifications of rainproof ventilation louvres to different special needs. An experimental environment with an air flow rate of 13m/s (30 miles/hr) and rainfall intensity of 75mm/hr (3 inches) may be relatively harsh but it is still a highly effective environment that is close to the actual rainproof performance environment.