Hammersmith and Charing Cross NHS Trust hospitals have an ongoing programme of efficiency improvement work undertaken in partnership with the Carbon Trust to reduce carbon emissions in line with Department of Health targets. As part of this project, over 70 WEG electric motors and variable speed drives have been installed at the two major London healthcare sites. The installation is expected to pay for itself within two years through energy savings
An initial site survey highlighted opportunities for energy saving on fixed speed fans and pumps serving heating, ventilation and air-conditioning plant throughout the sites. High efficiency EFF1 motors and CFW09 variable speed drives from WEG were specified and are reckoned to provide a substantial combined energy saving of up to 25 per cent over existing plant.
Making the decision to change over to energy efficient motors and drives was only part of the process. Patient care is both critical and continuous, hence WEG worked with an installation partner Deritend and the estates management team to meet strict health and safety requirements and complete the changeover and final commissioning within carefully co-ordinated time slots.
“The work needed careful management and planning so that the installation engineers could be given access to heating and air conditioning (HVAC) areas throughout both buildings, where the pumps and fans were located,” said NHS Trust Estates Manager Ian Svenson,. “We used relatively quiet times during the night for commissioning and switch over to provide an eight-hour window when individual areas such as operating theatres could be powered down.”
A logistical challenge
Varying in size from small 5.5kW pump motors through to 75kW units for the main air movement fans, the logistics were a constant challenge. Some smaller pieces could be wheeled in on a trolley and positioned by hand: others, however, required the removal of roof panels to lower units into place using a crane, all without materially affecting normal hospital operation. The entire project totalling 72 motors and drives was completed on schedule.
Russell Maccabe, WEG Area Manager, said: “In field tests, replacing standard two- pole 18.5kW motors with a WEG W21 high-efficiency motors had shown savings of over £500 per motor per annum. For users this means that payback times can often be measured in months.”
Control and power management panels, including the drives, are all controlled via a Trend Building Management System (BMS) using SCADA-style PC visualisation to make the new equipment visible to the facilities teams. The integration went very smoothly with a simple plug-in connection to the BMS system, allowing finely tuneable and efficient variable speed control in place of mechanical throttling of pumps and baffles in air movement systems.
