Variable speed drives shave £15,000 off hospital energy costs 01 September 2014

Bedford Hospital is reporting savings of £15,000 a year on air handling costs since installing variable-speed drives (VSDs) from ABB partner Inverter Drive Systems (IDS).

The project involved fitting ABB drives to four AHUs (air handling units) in the hospital's maternity and pathology departments – cutting air volumes to save energy.

"We were attracted by IDS' proposal, particularly by the low payback times of around a year they said we could achieve," comments Kevin Stephenson, estate manager for engineering.

The AHUs selected for retrofitting with VSDs are in the waiting rooms and other general areas of the neo-natal unit, maternity outpatients department, and pathology.

"We knew this would cause minimal disruption, as we could alter the air volumes and save energy without the need to meet the air change rates in more critical areas such as theatres," explains Stephenson.

Previously, the AHUs were used direct-on-line, with no form of control. IDS's solution involved four 11kW drives and one each of 7.5kW, 15kW and 3kW. All were three-phase, ABB HVAC drives, ACH550, with IP54 enclosures.

Before installation, IDS had predicted a speed reduction of 15% but has actually achieved 20%, equating to the energy saving of £15,000 a year, with payback of 11 months.

As well as the energy saving, the motors run quieter, also suffering less wear and tear and so reducing the maintenance.

Says Stephenson: "We were very pleased with the way the project went. IDS completed the installation on time and did what they said they would do."

Brian Tinham

Related Companies
ABB Ltd
Inverter Drive Systems Ltd

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