Hospital saves £9,000 on HVAC energy 11 October 2010

Medway Maritime Hospital in Gillingham, Kent reports saving £9,000 a year on its air handling units (AHUs) since installing variable speed drives (VSDs).

Trish Marchant, deputy environmental manager at the acute and general hospital, says management had been getting increasingly concerned by energy consumption of the AHUs in the three plant rooms – each with one supply and three extract fans Each with one supply and three extract fans serving it's a block.

"Our main driver is keeping our CO2 contribution low, as well as cutting energy costs, especially with the launch of the CRC Energy Efficiency Scheme," explains Marchant – adding that she asked ABB Drives Alliance partner Inverter Drives Southern to make recommendations.

IDS measured the power consumption and determined that the AHUs were costing more than £21,000 a year to run. The company also predicted that installing variable speed drives could cut this to just over £12,000, also saving 32 tonnes of CO2 per year.

IDS installed 12 ABB standard drives for HVAC, with ratings between 1 and 11kW, and worked with the hospital's BMS (building management system) provider on the I/O. now, at night, fan speed is set back to 80%, while during the day it is 90%.

"We were concerned about the quality of installation," says Marchant, "particularly that the cables and drives would be sited so they were easy to maintain. IDS did everything we asked."

She adds that she is now looking for similar applications that could benefit from VSDs. "I would definitely recommend the use of VSDs in other similar situations, particularly for older AHUs where the motors may be oversized."

Interestingly, this project was carried out with a loan from Salix Finance, a not-for-profit agency that provides interest-free loans to public bodies, such as NHS trusts. Eventual savings from the project are on target to achieve the £9,000 per year, giving a payback time of 2.5 years.

Brian Tinham

Related Companies
ABB Ltd
Inverter Drives Southern

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