Jaguar Land Rover installs solar air heating system

Atired industrial unit on an undistinguished business park is not the sort of venue normally associated with pioneering the uptake of green technologies, but the car manufacturer Jaguar Land Rover foresaw an exciting future for the dingy property on the outskirts of Leamington Spa when it took over the lease in spring 2008.

It was to be the home of a training academy where dealership staff from around the world learn how to service the hottest new Jaguar and Land Rover models. And the manufacturer also wanted to use the premises to encourage its dealers to think about green building technologies.

The job of deciding what technologies were appropriate fell to the manufacturer’s building engineering team, who did a lot of work searching the internet for suitable options. The team considered the potential of 30-odd technologies, comparing capital cost against energy saved, but two stood out as offering the best return on investment.

The most cost-efficient solution, unsurprisingly, was to seal and insulate the building. “Recladding costs were astronomical so we sprayed a 75mm layer of insulation on its inside to seal the building and improve its thermal performance,” says John Vickers, plant engineering manager at Jaguar Land Rover. The second most costeffective solution was to heat the building’s fresh-air supply using SolarWall, a passive heating technology new to the UK.

SolarWall is an unglazed solar heating system, which heats external air via a southfacing solar collector. The unit consists of a skin of perforated cladding installed as an additional skin to a building’s southfacing elevation, creating an air space between the collector and the insulated wall. The perforated cladding captures the warmth from the solar radiation falling on it and uses it to heat and ventilate the building.

CANADIAN TECHNOLOGY

The plant engineering team at Jaguar Land Rover worked with cladding maker CA Group, which is rolling out the Canadian technology in Britain, to design the 268m2 installation. It was fortunate that the south elevation has a steel-clad mansard roof, mounted above a windowless brick wall – the roof’s steeply angled lower slope was an ideal location for the SolarWall unit. The unit’s perforated steel skin, made from Corus’s pre-finished ColorCoat Prisma, was specified to be as dark as possible to maximise the solar heat absorbed and help it to blend with the existing cladding.

Inside the training centre, Jaguar Land Rover has installed a double-height workshop, classrooms and a cafe. Fresh air warmed by the SolarWall is drawn into the workshop by two fan units, located 30m apart, and supplied through ceilingmounted 500mm-diameter fabric ducts. A mixing box with motorised dampers, mounted on the fan intake, controls the ratio of fresh and recirculated air according to temperature.

Peter Phillipson, project engineer at Jaguar Land Rover, says the system is most effective in spring and autumn, when the outside air is cool and the sun is still warm. For example, at 9.30am on 29 September, the outside temperature was hovering at 9C and after passing through the SolarWall the air temperature had increased to 26C. At such times, the system can meet the ventilation requirement of one air-change an hour while maintaining the working environment at 20C. The tempered fresh air is drawn into the classrooms and kitchen from the workshop.

In winter, when the sun fails to shine, the fresh-air dampers shut down to the minimum setting of about 10% of total supply air, which is sufficient to pressurise the building to prevent cold drafts. The fans still run at full duty, however, to push air through the fabric ducts to eliminate the build-up of hot air at high level.

Even in winter, air drawn from inside the SolarWall will be warmer than the outside temperature because it captures heat escaping through the building. Additional heat is provided by two direct-fired gas air-handling units, on the north elevation, which Jaguar Land Rover retained when it took on the building.

In summer, when the outside air does not need to be heated, the fresh-air dampers on the SolarWall are closed and the original air-handling units are used to draw outside air into the workshop from the north elevation, where its temperature is coolest.

Phillipson has monitored SolarWall’s performance since the building opened last December. He says it is expected to save Jaguar Land Rover 80,000kWh of energy, or 19 tonnes of carbon.

SolarWall is particularly well suited to heating warehouses where the inside temperature is not critical, and Jaguar’s plant engineering team is now looking to install the product on other projects.

SolarWall is being promoted for new-build but, as Jaguar Land Rover has demonstrated, the benefit of using it for retrofit is that it is a standalone system, which means you don’t have to replace the existing plant.