Natural ventilation partnership brings unique offering to achieve excellence in energy efficiency

A unique natural ventilation combination from Passivent and REHAU can provide a low energy cooling solution for the commercial market.

The Passivent/REHAU solution combines the former’s passive stack natural ventilation with the latter’s AWADUKT Thermo ground-air heat exchanger, and is particularly appropriate for buildings with deep floor plans and/or restricted external facades.

Passivent’s natural ventilation uses inlets on exterior walls and/or windows to draw fresh air into the building, exhausting the ‘used’ internal air through high level façade ventilators and/or roof mounted terminals. Where fresh air is required but there is no suitable exterior façade, the REHAU ground-air heat exchanger draws fresh air into the building through the ground and pump it into the depths of the building via a low energy fan, simultaneously using the earth’s constant temperature of between 7-12° to pre-heat or pre-cool the incoming air, and relying on Passivent’s extracts to ensure a background ventilation requirement in line with Regulatory requirements.

In domestic environments, a Co-efficient of Performance (COP) of up to 50 can be achieved, with 20 realistic in commercial buildings.

And the strategy is already being proven in ‘real life’, in Carclaze School in St Austell, Devon, a BREEAM rating of ‘excellent’ was attained. The two storey school was set into a sloping site, limiting available facades. M&E contractor EIC designed the ventilation so Passivent Aircool units in the walls and windows optimized air flow in classrooms, complemented by an Airscoop providing both fresh air in and ‘used’ air out on the upper ground floor; the REHAU ground-air system providing fresh air into the ground floor areas with limited or no external facades. The whole ventilation is integrated into 18 zones for temperature and CO2, monitored and flow rates adjusted as required by Passivent’s iC6000 controller.

Wayne Aston of Passivent elaborates, “The combination of our ventilation and the REHAU ground-air heat exchanger system is unique, and gives designers a proven, highly effective, integrated and sustainable solution for background ventilation with a COP second to none.”

Adds Steve Richmond, Business Team Leader- Renewable Energy at REHAU, “The combination has optimum flexibility to meet designers’ needs, as it offers a true ‘mix and match’ option to achieve the flow rate required whilst significantly reducing energy consumption.”

Passivent ‘commercial’ natural ventilation systems already qualify for credits under the BREEAM verification system and contribute towards achievement of Building Regulations Approved Document L (Conservation of Fuel & Power). Further, they reduce energy consumption over air conditioned buildings by up to 50%, yield 15% savings on capital costs, 75% savings on maintenance costs, and eliminate the need for a separate plant room. Natural ventilation is further proven in research to reduce incidence of ‘sick building syndrome’, and improve occupant performance in all environments.

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