E-Vent® is a new natural ventilation system with applications for both industrial and residential buildings with metal roofing. Seated alongside (and in place of) the ridge cap, E-Vent® extracts hot air from the roof space with an innovative design that harnesses the combined natural forces of differential air pressure and convection. Designed by architect Ean McDonald to overcome the many problems with existing ventilation systems on the market, E-Vent® has been found to be a highly effective, efficient and environmentally friendly venting solution (hence the ‘E’ in E-Vent®).


  • E-Vent® reduces heat indoors
  • E-Vent® is a part of the roofline and is barely noticeable
  • E-Vent® provides protection from airborne embers
  • E-Vent® effectively removes noxious gases, airborne bacteria and household odours
  • E-Vent® reduces air conditioning costs
  • E-Vent® is a low, one off cost
  • E-Vent® requires absolutely no maintenance
  • E-Vent® is a no cost, no fuss installation


Using principles first expounded by Bernoulli and Venturi in the 18th century, Architect Ean McDonald created his E-Vent® natural ventilating system, now available in various forms from Combined Metal Industries. Bernoulli propounded that the pressure of a moving body of air or water is least where the velocity of the mass is greatest. In simple terms, by accelerating an air flow across a given surface or opening, a pressure differential can be created to produce a natural force and that harnessed force can produce power.

It is applied in aircraft flight and venturi systems generally. E-Vent®’s harness this natural power by creating low pressure areas on the upper and downwind sides of the vents creating a natural and effective exhausting air pump. That in turn means that air at normal pressure within a building will be literally sucked out by wind flow. And on the stillest of air days, E-Vents® still work by reason of simple convection or ‘stack effect’.


  • Ridge vent strips
  • Sloped roof skylights
  • Flat roof skylights
  • Vents for wet areas such as bathrooms, kitchens or toilets
  • Condensation prevention and extraction
  • Fire warning vents
  • High fume or dust extraction
CMI E-Vent
CMI E-Vent


  • Cost-free operation
  • Early smoke detection
  • Condensation management
  • Leaf and vermin proof
  • Rain draining
  • Satisfies all building laws
  • Tailor made to each installation
  • Non rusting materials
  • No moving parts = no maintenance

E-Vent® is manufactured by Combined Metal Industries to ISO 9002 standards E-Vent® Patent No. 673749.