E-Vent® and Whirlybird: The next Generation of roof ventilation

By February 13, 2019Roofing
CMI E-Vent Steel Roofing Supplies

Effective roof ventilation is important when it comes to the energy efficiency of your home. A standard roof space can quickly trap heat and warm your home – accounting for the majority of your home’s heat gain in summer and contributing to musty smells, bacteria growth and even condensation. With rising energy costs, proper roof ventilation can help keep your home naturally cooler in summer through intelligent airflow and with CMI’s patented E-Vent®technology, you can keep it cooler more effectively.


Roof ventilation technology: Whirlybirds

There are a large variety of roof ventilation options that have been developed and have evolved over the past couple of decades. A popular option is the Whirlybird (sometimes known as a turbine vent), which lets cooler air in through ceiling eaves and expels it through a turbine near the peak of the roof.

This creates an air pressure vacuume that can be operated mechanically (turning continuously) or passively (wind spins the turbines).

Whirlybirds are full of moving parts, whether it is a passive or mechanical unit they will be prone to noise and wear. Bearings and parts will wear or loosen over time and need to be maintained (and they aren’t the easiest object to get access to!)

Due to their design, whirlybirds also have to be installed on the rise of the roof, rather than at highest peak – not the most efficient location for something that is designed to expel the hottest of air.


A better solution?

There are many solutions on the market that are more effective at roof ventilation then whirlybirds. These range from solar powered devices to intelligent vents, but nothing beats the intelligent design and simplicity of CMI’s E-Vent®.


E-Vent®: the next generation in roof ventilation

CMI’s patented E-Vent®technology was invented by architect, Ean McDonald who used air pressure principles founded by Bernoulli and Venturi in the 18thcentury to create a natural ventilation system that works better than anything on the market. With no moving parts, practically invisible installation and centuries of science behind it – it is the next generation of roof ventilation.


How does E-Vent®work?

The E-Vent®system harnesses the combined natural forces of differential air pressure and convection to accelerate the airflow across the roofs surface, extracting warm roof space air.

E-Vent® harnesses 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’.

CMI E-Vent


Why is an E-Vent®better than alternatives?

E-Vent’s®have a number of benefits over traditional ventilation methods:



  • Is part of the roof line, sitting on the very peak of the roof, invisible from the street
  • Provides protection from airborne due to ember guard
  • Effectively removes noxious gasses, airborne bacteria and household odours
  • Low cost compared to alternatives
  • Requires absolutely no maintenance
  • No moving parts, no noise and no reliance on wind
  • Extremely easy to install – no need to cut into roofing sheet


Where can I get one!

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

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