The environmental controls at the John Lewis headquarters in London dated back to 1975 and were a hybrid of old pneumatic terminal unit and AHU plant controllers, with Trend outstations integrated into the MPHW boilers and absorption chiller systems. While maintaining the site to ensure support of the old systems, we worked with the client to fully upgrade the

controls to Trend and integrate them onto the new BMS, thereby providing greater control and consequently energy savings.  As part of these works inverter drives were also added to the underground car park fans, with their operation now based on carbon monoxide levels rather than the previous fixed time schedules, this modification alone provided a pay back for the initial inverter capital investment within 2-years.  When a new building was being aquired adjacent to the headquarters, the inherited control system was proving too problematic. The system was LON based and to improve the system's reliability and maintainability, Marsh System were successful in obtaining an order to upgrade the system.  The system selected was based around the Tridium range of products for the main plant, with LON based Viconic controllers being used on the terminal units.