Heating, Ventilation and Air Conditioning

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.

Classification of Mega Union’s Rainproof Ventilation Louvre Systems

Performance specifications should consider the design of the speed of airflow passing  through the inlet.

As performance classification is dependent on air flow rate, it should be specified when designing the speed of air flow passing through louvre inlets. The above figure illustrates the actual rainproof performance under experimental conditions. This experiment represents the harsh weather condition in Britain.

The HEVAC standard is currently formally promulgated and is technically equivalent to the European Standard BS EN13030.

The precision levels of louvre performance tests have been continuously increasing alongside the continuous improvements and upgrades of the HEVAC experimental standard. Mega Union closely follows international standards for quantification tests and has passed the one and only globally recognised British BSRIA test, thus proving the excellent performance of Mega Union’s rainproof ventilation louvres.


Recommendations for the choice of rainproof ventilation louvres are based on the actual
specified inlet air flow rate.

Louvre systems are popular with designers for many applications in industrial and commercial buildings.

iDAStech® solar shading systems are available in many material options, shapes and sizes, fixed or movable.

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