Natural-ventilation and lighting upgrade comes in cheaper than like for like replacement

Published:  02 February, 2011

Passivent, natural ventilation
Replacing the facade of this building for Defence Estates and installing Passivent natural-ventilation and daylight systems was cheaper than retaining the existing facade and replacing mechanical-ventilation plant.

The green credentials of a remodelled 2-storey building of the Ministry of Defence at Imjin Barracks have been enhanced with the provision of natural ventilation and natural daylight using Passivent systems. Defence Estates, the property and estates-management arm of the MoD worked with Debut Services on the projects, which will centralise the service and veterans agency at the Barracks. A key criterion of the design brief was for the 3800 m2 1960s building to achieve an ‘Excellent’ DREAM, the defence equivalent of BREEAM.

Chris Kenny, project architect with Stride Treglown, explains that the original building was 80% mechanically ventilated. ‘We needed to replace the facade, so we decided to explore the use of natural ventilation through openable windows and Passivent natural ventilation to ensure good levels of ventilation throughout the deep plan. This option was actually cheaper than keeping the facade and replacing all the M&E plant associated with mechanical ventilation.

‘We were also concerned about providing adequate daylight, especially in the deep-plan circulation areas. Passivent’s Sunscoops optimise natural light across the floor space, improving the quality of that space and reducing running costs.’

Six RAD Airscoops, ventilation terminals divided into four chambers, on the roof draw fresh air through their windward chambers into the upper storey to displace used air via the leeward chambers. Incoming air can be controlled to avoid draughts.

On the ground floor, five Aircool motorised ventilators above the windows draw in fresh air. A roof-mounted Airstract acts as a passive stack to exhaust used internal air. All ventilators are operated by an iC7000 controller, which monitors indoor air temperature and quality (including CO2) and adjusts the ventilation rate in larger office area to maintain a fresh-air supply of 10 l/s per person.

Daylight enters the building via 38 Sunscoop tubular rooflights 350 mm in diameter. Each Sunscoop has a Light Sun Deflectors to increase natural lighting inside by up to 20%

For more information on this story, click here: February 2011, 104

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