Contractor enjoys prefabrication benefits for the first time

Prefabricated services modules have saved one week per floor in installation time in a refit of three floors of 10 Exchange Square in the City of London. Phil Mardle, construction manager with M&E contractor Bancroft Group, says, ‘This was our first exercise in the use of off-site prefabricated services in this manner, and we therefore used it on a fairly limited scale. We will almost certainly, however, expand the scope of its use on future projects.’ The refitted floors of this 15 200 m2 headquarters complex developed by British Land, comprise mainly cellular office accommodation, with IT service suites and meeting and ancillary rooms. Air conditioning for each floor is supplied by 67 bespoke 2-pipe, chassis-type fan-coil units with electric heater batteries and connected to existing chilled-water risers. MEP Solutions designed and produced the modules. The predominantly Mapress copper tube and pressfittings in sizes from 15 to 67 mm on the new chilled-water circuit were preinsulated and mounted off site to the modules, along with Crane Dominator valve sets and pre-insulated Alupex piping with terminations matching the valve sets and fan-coil units. All services except chilled water are independently routed and connect directly to the fan-coil units. Modules were delivered by MEP ‘out of hours’ at weekly intervals to ease site logistics. They were stored on the unoccupied fifth floor and called off as required. Unloading each shipment of modules, which were made in 2.8 m lengths to fit the building’s goods lift, took about an hour and a half. Each floor was fully fitted with modules by six operatives in three days, with a further week required to connect all 201 modules to the Alupex piping and fan-coil units. Phil Mardle explains, ‘We chose to split the module positioning/fixing and interconnection operations, with our duct workers offloading, positioning and fixing, and final coupling together by our pipe-fitting operatives. The need for just four fixing points made initial installation easy, and the training provided by Mapress in the use of their pressfitting tools enables our pipe fitters to carry out the latter operation without any undue problems.’ Main contractor is Bovis Lend Lease Interiors with Chapman Bathurst as building-services consultant.