EESI recently completed work on a building that required a natural passive ventilation system. Passive ventilation involves pulling air in from the outside at a high level and pushing it into the building at low level, using roof vents to create air flow up through the building.

“The traditional method is to install a bunch of big fans in the ceiling, but if you’re not putting air back in, you’re not getting a nice air flow,” explained Project Manager Derek Hyatt. “It was the machine shop which was experiencing temperatures well above 30°C during the summer months. They were getting portable fans in, opening all the roller shutter doors to try and get some airflow for the staff to improve working conditions. Not only didn’t it work, there was also a security risk when the building had all the roller shutter doors up.”


Because of the nature and complexity of the project, the company brought in an engineering consultant who invited EESI and 2 two other contractors to tender for the job. One contractor declined to tender because of the complexity of the project.

“They needed a passive natural ventilation system. The consultant’s design and the nature of how they wanted the work to be carried out wouldn’t have worked, partly because of the complex shape of the building and would have involved putting in so many units that there wouldn’t have been any wall left. We knew the solution offered by the consultants wouldn’t have worked and tactfully explained why. Then we worked with the client to better understand their requirements before redesigning the system. At the time it was a risk to us getting the work, but it worked out well in the end as they now have a system that works beautifully – and some wall space.”



Our solution involved 22 ventilation modules which we designed and installed. Each module consisted of a fan, a filter box, a damper so we can modulate the flow of air, the control system, ambient sensors, rain sensors and modulating valves for control of the airflow. We zoned the areas with different requirements – they had examples of what we’d call ‘hot spots’ where it was constantly hot regardless of ambient temperatures, so we increased fan speeds in those areas. The entire system was inverter driven to make it energy efficient as it gives the ability to change the speeds of the fans depending on ambient and internal temperatures.

“There was a lot of pressure to get it installed before summer, which we’re pleased to say we did, and the difference was noticeable as soon as we had it running. People were coming up to the engineers and thanking them, which was really nice. We got genuine feedback from the staff in the offices saying what an improvement it was. Before it was stuffy, temperatures were unbearable, it was an unpleasant working environment. Now it’s a lot more comfortable and the staff are happier and more productive as a result.”


This effective cooling solution has improved working conditions which, in turn, has led to an increase in productivity and reduced the security and safety risks caused by open roller doors and portable fans.

To find out how EESI could help keep your building cool, call us today on 01453 821 550 or email

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