Windcatchers cut Tesco store's energy consumption

Monodraught Windcatchers have made a significant contribution to reducing energy consumption in a new Tesco Superstore near Manchester.

The supermarket chain set itself a target to reduce carbon emissions by 50 per cent from all its stores by 2020, as compared to a baseline of 2006.

Tesco exceeded this target when it opened its eco store at Cheetham Hill, Manchester, reducing the carbon footprint by 70 per cent compared to an equivalent-sized store built just more than two years ago.

These measures are delivering significant savings for the company, with a 48 per cent reduction of the store's fuel bill based on 2006 baselines.

An ITN film production featuring the Monodraught Windcatcher natural ventilation systems installed at Cheetham Hill was shown at this year's Nemex exhibition.

In the film, Bill Moss of Tesco's Cheetham eco store said: 'The fresh air that comes in makes for a better working environment.

The Tesco billboard in the store reads: 'Our roof vents let air flow naturally, so we use less energy to heat and cool the store.

The 52,000ft2 (4,830m2) Cheetham Hill store, located in a redevelopment area near Manchester, is built to an 'environmental format' that is intended to provide a 'low-carbon blueprint' for future Tesco stores built in the UK.

Steve Howard, chief executive of the Climate Group, a non-government organisation that has worked with Tesco on its low-carbon strategy, urged other companies to use the Cheetham Hill store as a template for future low-carbon buildings.

Dean Hyndman, a senior electrical engineer with the project's consulting engineer Scott Wilson, said: 'We were asked to examine environmental issues in order to reduce the carbon footprint for the Cheetham Hill store and all other Tesco stores in the future.

'One of the key energy-saving initiatives was to reduce the air-conditioning load by providing natural ventilation where practically possible,' he added.

Hyndman estimates that the energy savings achieved by replacing air conditioning with Monodraught Windcatchers will be in the region of 20 per cent.

Scott Wilson is a multi-disciplinary international design and engineering consultancy, which provides sustainable, integrated solutions to meet the environmental needs of clients.

The consultancy has previous experience working with Monodraught and was keen to use bespoke Windcatchers to give the 'environmental-format' stores a more individual identity.

The 11 4m-high oval-shaped Windcatchers installed at Cheetham Hill are said to be distinctive and are finished in the blue and grey Tesco livery.

Windcatchers, together with Monodraught Sunpipes and Suncatchers, have also been installed at the new Tesco Express store in Hinckley, Leicestershire, which opened in June 2008 and is also based on the eco-store concept.

The design of Monodraught Windcatchers is based on technology that is making a positive contribution to the elimination of air conditioning, which, in turn, reduces the carbon emissions produced by burning fossil fuels.

Windcatchers are described as an effective means of harnessing the wind's potential as a renewable-energy source.

Roof mounted and designed to operate with virtually no moving parts, they use established atmospheric principles and the natural effects of the wind to bring fresh air into a building and extract stale warm air, using only natural forces.

Warm air rising to roof level decreases the air pressure within buildings, allowing cooler air to enter the building via the Windcatcher units.

The resultant change in air pressure produces sufficient airflow to make the space comfortably fresh.

Wind blowing onto the windward side of a ventilation stack increases the throughput of air and encourages stale and stagnant air to be extracted through the leeward side of the roof unit.

Opposed blade dampers - made from recycled plastic, with their ventilation rate controlled by the building's BMS system - can precisely control airflow through the system, dependent on the internal temperature.

At night, they can also be programmed to open fully, providing a downwash of cool air that purges the building, leaving the interior feeling fresh and clean for the following morning.

Windcatcher units can be controlled individually or by a central control panel, which can be fitted with a spring/summer/autumn/winter switch to ensure that dampers only open for night-time cooling during the summer months.

At other times of the year, dampers can be set to provide trickle ventilation without the problems of cold draughts.

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