John Lewis superstore uses Daikin air conditioning throughout
The cooling and heating requirements of the new John Lewis store in Cambridge are met by Daikin VRV systems
John Lewis’s new store in Cambridge is three times larger than its previous store in the city. Its 13 400 m2 is air conditioned throughout by Daikin VRV and Sky Air air-conditioning systems designed and specified by CSA Consulting Engineers of London and installed by Daikin D1 installer Breathe Air of Cambridge. VRV air conditioning for this project was selected for its ability to sustain long pipe runs, space-saving capabilities, flexibility of installation and economic installation costs compare with a chilled-water system of similar capacity. The new store has five floors and is an innovative combination of new build and existing Grade 2 listed structures with attractive visual effect. There are 15 VRV systems comprising a mix of heat-recovery, heat-pump and mini VRV-S types selected according to the cooling and heating requirements of the various floors and areas. Heat recovery is used for the restaurant, TV/audio, basement and open-floor sales areas. Mini VRV-S systems serve smaller areas such as reception and interview rooms. The two communications rooms have Sky Air Super Inverter systems. All other floors are served by heat-pump systems. The mini VRV systems have cooling/heating capacities of 11.2/12.5 kW. Heat-recovery and heat-pump systems have cooling/heating capacities of 22.5/55 kW. All the VRV outdoor condensing units are at third- and fourth-floor levels. Conditioned air is supplied by ceiling cassettes, ceiling ducted and wall-mounted fan-coil units, the last being in the listed buildings — where there are no ceiling voids. External packaged air-handling units with DX coolers and gas-fired heaters deliver tempered air (25% fresh air and 75% recirculated) to each conditioned area. The total cooling and heating loads are 250 kW and 75 kW, respectively. Internal design temperatures are 22°C ±2 K in summer and 20°C ±2 K in winter. Overall control is provided by a Daikin I-manager in the building manager’s office and linked by a Daikin BACnet Gateway to the store’s BMS. Local temperature control is provided by remote, wall-mounted room controllers and temperature sensors in the room return-air grilles.