Gilberts’ bespoke capability helps minimise impact of green belt development

  • 8 Nov 2019

The environmental impact of a £15m three-storey Centre in the heart of the Surrey green belt, within a Grade II listed park, is being controlled by optimisation of natural resources by Gilberts.

Working on the design & build project for contractor Blenheim House Construction (BHC), Gilberts has produced a natural ventilation strategy to a bespoke design, to ensure the architecturally-dramatic new Activity Centre, measuring 4000 square metres, at St George’s School in Weybridge, will be appropriately aired, irrespective of occupancy and activity levels within, and with minimal impact on its external surroundings. 

Joe Anderson, BHC project surveyor, commented: “The project was a challenge that we were confident Gilberts could meet.

“The site geography provided challenges: the building has been sunk into the surrounding landscape to give level approaches at ground and second floor – there’s a height difference of at least 8m- which impacts on airflow around the building. 

“Gilberts also had to deal with the ventilation’s ability to cope with occupancy and activity differences ranging from a whole-school assembly of 1000 or more pupils and staff, through to part of a class using the climbing wall or cricket nets.

“It had to balance human occupancy and activity alongside the potential heat gain as a result of large areas of the building featuring floor to ceiling glazed sections. 

“Beyond the technicalities, the ventilation had to reflect the high aesthetic standards of the project.” 

With its in-house design and manufacturing capability, Gilberts was able to engineer a tailor-made rooftop ventilation terminal (penthouse) design to deliver the required air flow and a weathertight fit onto and through the omni-directional curves of the roof. 

In total, 16 PHH75 roof terminals, each 1900mm x 100mm x 14mm, with boost fans in those over the main sports hall area, have been fitted to the Glulam beam and CLT panel roof.

Almost all of the penthouses provide natural ventilation into the sports hall below; those over the lower areas of the roof  feature additional fan assistance to ensure adequate delivery of fresh air in their more sheltered location.

On the four vertical facades, 30 x Mistrale Façade WHC75 high performance ventilation louvres in a deep channel frame have been integrated into the rainscreen cladding to provide ventilation to the café, viewing platform, fitness suites, studio, toilets and changing rooms.

Louvres up to 5570mm x 800mm were produced to create an aesthetic solution. 

A further 12 louvres provide air for the sports hall also, including LTHW heating coils, to reduce temperature differentials between fresh, incoming air and the existing internal atmosphere, and deliver appropriate quantities of fresh air across the 30m clear spans within the main hall.

A further two WHC75 provide screening and ventilation to the rooftop plant, and two louvre double doors ventilate the switch room and plant room.

Stefan Bamber, Contracts Manager, commented: “St George’s Activity Centre has been just the sort of challenge that inspires the team at Gilberts.

“It empowers us all to work together to develop a solution that meets stringent demands in terms of performance and quality, that will work now, and for the lifetime of the building.”


Gilberts of Blackpool,
Gilair Works,
Clifton Road,
FY4 40T

Phone: 01253 766911
Fax: 01253 767941

Visit Gilberts of Blackpool's website

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