Metering and Monitoring
t-mac first began by metering mains energy consumption, sub-metering air conditioning and lighting, as well as monitoring environmental conditions such as light and temperature levels for an initial six-month period. Data collected was then viewed and analysed through t-mac's energy analysis software and immediately showed inefficiencies in energy consumption.
Thanks to the sub-metering data, the main 'causes' of these inefficiencies were identified as air conditioning and lighting. As well as analysing the metering data, t-mac was monitoring environmental conditions within the store as well as equipment performance through monitoring a/c set-points. This immediately showed that staff were manually adjusting temperatures, often setting the a/c to 28-30 degrees centigrade; an inefficient use of the a/c equipment.
The metering and monitoring data gathered over the initial period provided a valuable insight into how the store was being used by the staff. It allowed the store to implement a control strategy with t-mac that would immediately eradicate the excess waste energy consumption caused by inefficient equipment use and performance.
Starting with the a/c, t-mac stopped local control, which prevented staff from tampering with the settings. The a/c was then to be controlled by t-mac in accordance with inside and outside temperatures during business hours. Finally, interlocking a/c with the over-door heater ensured that this was only used when the a/c was in heat mode. Lighting was the next activity to be controlled by t-mac, this was also set according to business hours but, with the use of Passive Infrared (PIR) detection sensors, was to be controlled according to occupancy throughout the store.
Comparing the month of June 2010 (before controls) with August 2010 (after controls) the results speak for themselves:
- 20% overall energy saving achieved by the store – consumption profile peaks were reduced from 24kW to 16kW
- 82% saving in a/c consumption – consumption profile peaks were reduced from 7.5kW to 3.6kW
Further savings were identified through the store's marketing lights following a trial control strategy which showed that an additional 23% energy savings could be achieved should these be switched off out-of-hours. t-mac's work with the Nuneaton store demonstrates how sub-metering and monitoring are essential to identify where inefficiencies in consumption lie. Then, by adding controls, high peaks of energy consumption can be reduced and in some cases eradicated.