Benefits
  • Reduction in average kWh consumption of 15%
  • 347,464kg in projected annual carbon dioxide emissions savings
  • Estimated annual financial savings of £76,547
  • Return on investment - less than 10 months
  • Reduction in maximum demand charges
  • Extended equipment life cycles

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The Link Ice Rink and Leisure Complex - Swindon

Published 2009

In conjunction with the Council's green initiatives including participation in the Local Authority Carbon Management Plan, the Capita Symonds Energy's role is to assess the electricity usage across all of the Council's offices, Civic Campus and Link Centre.

The Link Centre is a large council run leisure complex, comprising an International sized ice skating rink, swimming pool, indoor courts, climbing walls, fitness studio etc and the local Library. The site operates seven days a week for 51 weeks per year.

The Centre was in the top 5 highest users of electricity in the Council's extensive portfolio with annual consumption of approximately 4.2million kWh (kilowatt hours). The implementation of voltage optimization using the Watford Control Powersaver has reduced our annual energy consumption by 15% with a consequential reduction in CO² emissions of over 347,000kg of carbon.

Taking into account both the direct and indirect savings afforded by the scheme, the Powersaver achieved a return on investment within 10 months. Powersavers have now been installed at several locations within the council's control.

Bruce Stone
Associate Director, Building Services
Swindon Capita Partnership
CAPITA SYMONDS

Background

The leisure complex would normally run anywhere between 400kVA and the maximum demand of approximately 750kVA, the overnight base load was approximately 300kVA. On site voltages (Fig 1) were high, peaking at just under 250V (P-N), fed by a single sub-station 1000kVA transformer. Capita Energy Team have already implemented a number of energy saving measures, typically fitting high frequency ballast lighting and variable speed drives to some of their larger motors.

Project

Installation was reasonably difficult with the main switch room located in the basement plant room of the centre and existing plant equipment restricting access. An additional plinth as flood protection (Fig 2) was requested. The existing ACB main breaker was re-utilised reducing the overall cost of installation. Due to the limited access it was decided to install of three single-phase units instead of the normal three-phase unit. The model PSR16-R15-1P-01 specified at 1441 Amps per phase, 318kVA at the 221V (P-N) set output voltage, complete with an external bypass switch allowing the client full control and independence over their supply and with enough excess capacity for future growth. All preparations were carried out beforehand with the final connections made within a four-hour period on a Sunday evening, causing the least disruption to the client.

The Powersaver outputs were set to 221V (P-N) as the optimised setting, giving just in excess of 220V (P-N) at the furthest point on site as requested by the Client.

The initial survey estimated a saving of a minimum 14% of the overall consumption. The client required Watford Control to prove these savings as confirmation of their own long-term tests. It was decided to utilise the Powersaver ability to adjust phase voltages whilst on-line and load. A medium (Fig 3) and a short (Fig 4) term tests would be performed, in each case returning the site voltages back to near maximum and then reducing again to the optimised setting. Results from these tests combined with other test data will allow the actual savings to be calculated.

The site voltages were increased to the maximum and allowed to run for a period. Then reduced to the optimised setting of 221V (P-N) within less than a minute and allowed to run for the same time period. The step change in voltage (all three-phase voltages are summed and averaged for clarity) and the consumption are clearly visible. The results were analysed and comparisons made with the short-term tests.

Again, the site voltages were increased to maximum and allowed to run for a short period and then returned to the optimised value, this sequence was repeated on several occasions in short succession. The step changes in voltage (again all three phase voltages are summed and averaged for clarity) and consumption can be clearly defined. Analysed together with the previous results from the medium term test and other data, the calculated savings for this site will be approximately 15% of the usage, an increase over the previous estimate.

Summary

The consumption of the Link Centre was 4,258,134kWh at an annual cost of approximately £510,310. The implementation of Voltage Optimisation utilising the Powersaver has now reduced this to 3,619,414kWh a saving of 638,720kWh, a consequential reduction in emissions of 347,464kg of CO² calculated at 0.544kg CO²/kWh. The cost savings of £76,547 per annum achieved a return on investment within 10 months.