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Installation of Variable Speed Drives


Leicester City Council has some very ambitious environmental commitments to reduce energy and water use in its buildings. The Council is committed to halving the amount of energy it was using in 1990 by 2025 and aims to get 20% of all its energy from renewable systems by 2020. For many years Leicester City Council has played an active role in encouraging and supporting measures that protect the environment. This was recognised in 1990, when Leicester became Britain’s first ‘Environment City’. Leicester City Council has since adopted a number of ‘green’ policies, ensuring that its own services and activities meet the high standards it encourages others to adopt.

Braunstone Leisure Centre was opened on Monday, 6th December 2004. The Centre includes two community swimming pools - a main pool and a teaching pool. An energy survey of the motors that drive pumps and fans within the Leisure Centre was carried in June 2005. The survey found that swimming pool motors would normally run flat out for at least 15 hours a day, 7 days a week consuming increasingly expensive electricity.

Consequently, the use of variable speed drives to control the poolwater circulation pumps was investigated. This energy efficiency measure would allow the Leisure Centre to slow down or speed up the motors according to demand, rather than running them constantly, at full power. It was decided that variable speed drives should be installed, and this took place in August 2005.

Braunstone Leisure Centre

Building details

Type of building: Leisure centre with facilities including two swimming pools, a fitness suite, a crèche and nursery with outdoor play area, a sports hall with six badminton courts and spectator seating, a conference/community room, a first aid room and a cafeteria.
Year built/ Floor area/ Operating hours: 2004 / 5011m2 / Monday - Friday 6.30am - 10.00pm, closed 9am - 11am Friday, Saturday - 8am - 5pm, Sunday 8am - 6pm
Measures installed: Five variable speed drives (three x 18.5 kW and two x 15 kW)
Energy/CO2/Water label (before and after improvements if possible): For 2006, after installation of the variable speed drives, the Display® ratings for the leisure centre were:

Energy: B

CO2: B

Water: C


_ The cusum graph below shows the reduction in consumption after the installation of the variable speed drives.

_ Annual saving of 240,000kWh, €26,000 (£18,000) and 103 tonnes of CO2 have been achieved.


Project Description

Aim To reduce the electricity consumed by the swimming pool pumps through the introduction of variable speed drives to vary the motor speed according to demand.
Key points This project involved the installation of five variable speed drives on all the main pool and training pool circulation pumps, as follows:

_ Three x 18.5 kW (main pool) and two x 15 kW (training pool).

_ The drives were installed on the 3rd of August 2005 allowing the Leisure Centre to slow down or speed up the circulation pumps according to demand, rather than running the motors at full power.


_ The graph below shows electricity consumption at Braunstone Leisure Centre before (pink line) and after (blue line) installation of the variable speed drives. The aqua line at the bottom of the graph shows the kWh savings and the purple rising line shows the cumulative savings.

Reason for inclusion as Shining Example: This Shining Example demonstrates the amount of energy that can be saved through the use of a variable speed drives to control the motors used to pump swimming pool water. This saving can be achieved with no measurable impact on water quality.


Costs &


The total cost of implementing the measure was €28,900 (£20,063). This was funded through though the Council’s Local Authority Energy Finance (LAEF) scheme. In the first year this produced an energy saving of 240,000 kWh and a cost saving of €25,900 (£18,000), giving a payback period of just over one year.
Benefits The variable speed drives have contributed to reducing CO2 emissions through the reduction in electricity consumed. In the first year, 240,000 kWh of electricity was saved. No measurable impact on the water quality in the swimming pool was found.

Partnership details

Partners&Roles The project was funded through the Council’s Local Authority Energy Finance (LEAF) scheme. The LAEF is available to all local authorities in the UK. An initial fund is established through an investment from the Carbon Trust, which is matched by the local authority. This money raised is used to finance energy efficiency projects that can make energy and financial savings. The selected projects should be able to repay the investment over five years from the money they have saved on their energy bills. The repayment is used to replenish the fund, making it self-sustaining.

_ The Carbon Trust is an independent company funded by the UK Government, which works with UK businesses and the public sector to cut CO2 emissions and develop commercial low carbon technologies.



Achievements In addition to an energy saving of 240,000 kWh in the first year, there has been no measurable deterioration of the quality of the pool water, even though the flow rate of water in the pool was lowered slightly.

_ The performance of the variable speed drives is monitored by the Council’s Energy Management Team, using their city-wide intelligent metering system, which the Braunstone Leisure Centre is part of.
Lessons Learned The energy and monetary savings achieved through the installation of variable speed drives at Braunstone Leisure Centre has prompted the installation of this energy saving technology in other leisure centres.

_ For future projects, the size of the pumps needed to cope with the process, application or flow should be investigated during the design stage. This opportunity was clearly missed when the Braunstone Leisure Centre was being designed, but corrective action was taken as soon as the high consumption was highlighted.

To know more



Leicester City Council
Contact Prakash Patel
Phone +44 (0)116 299 5142

Arrangements to visit Contact Prakash Patel

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