Other Systems 

Another form of ventilation - not covered directly by the suggestions in the England & Wales Regulations - these products also offer high levels of air filtration and sound attenuation. 

Sonair - Used for buildings where noise or air pollution is a problem.

Vent-Trex - A combined overhead extract fan and trickle ventilator for kitchen and bathroom extract.

This makes them ideally suited to either new build or refurbishment situations in built-up areas or brownfield developments. With acoustics becoming a more important factor in more densely populated areas, the requirement for sound attenuating ventilators has increased.
As standard/acoustic trickle ventilators cannot provide the attenuation levels necessary, more sophisticated solutions are required. The Sonair achieves acceptable noise reducing levels.