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Inspiration for New Ventilation System Sparked by Transit Van

We have come up trumps with an innovative and cost effective ventilating solution at a housing development in Poole, Dorset.

The system, which uses a spinning cowl more commonly found in transit vans and commercial vehicles, has the potential to be introduced in new developments across the UK.

The system has been approved by both the National House Building Council, the UK’s largest building control inspector and the Borough of Poole Environmental Health Department and has now been operational for two years without fault.

The Idom Merebrook team has had a long term involvement with the development of the Poole project from initial feasibility reviews through to the detailed design and construction management and validation to ensure the site, which was first a quarry then landfill has been suitably remediated for residential development.

This has included managing contaminated soil remediation, ground stabilization, perimeter gas ventilation and sub-structure gas protection systems.

The redevelopment of former industrial facilities and landfill sites typically requires detailed remediation. Landfill sites provide a very specific challenge for engineers as the deposited waste content can be varied, leading to complex geotechnical challenges and risks to both surface and ground water.

In addition, many landfill sites generate high volumes of gas, predominately methane and carbon dioxide, which uncontrolled can provide a significant risk to human health of the end users of the redeveloped sites and also to those surrounding such developments.

A common solution to this is the installation of stainless steel aspirating cowls on sites, which work effectively to draw gas from beneath structures. However, they are both unsightly and notorious for failing, resulting in expensive replacement costs and a reduction in the efficiency of the entire gas ventilation system.

The development in Poole, which was a former landfill site required a solution offering a passive ventilation system with excellent venting capacity, no light reflection, long life, maintenance free, low cost and superior aesthetics.

A number of options were considered such as gas protection systems utilizing fans and pumps, however active systems are the last resort for gas protection, generally passive ventilation systems are preferred. These require little or no running costs or ongoing maintenance, providing a lower lifetime cost to the householders and greater certainty to regulators.

Idom Merebrook began researching alternative products, with a focus on improving the aesthetics whilst maintaining ventilation efficiency. Various products from across Europe were considered ranging from galvanized products from Spain to locally sourced chimney cowls.

In essence these were all a slight variation on the traditional aspirating cowl. None offered a significant improvement in appearance. After much research the team took inspiration from a transit van.

Project Manager, Rob Giles commented:

We noticed that the plastic rotating cowls on top of police dog vans operated on the same principle as the traditional stainless steel cowl which was to be replaced. After checking that the flow characteristics were equivalent and following discussions with the suppliers and regulators it was concluded that matt black, plastic cowls were better suited for the application.

 Not only do the cowls perform effectively at ventilating ground gases, they are smaller, quieter, less obtrusive and come with a 10 year warranty.”

Plastic rotating cowls are also used widely on buses, caravans, horseboxes trailers, caravans and motorhomes to improve airflow and ventilation. From a building services and engineering perspective the cowls are simple and quick to install, eco friendly, reliable and safe.  They are designed to rotate and therefore extract in the lightest of winds (circa 5 mph).