Case Study
Energy Demand Management
At Westfield centres in the United Kingdom various initiatives were implemented during 2011 to reduce energy demand in recognition of the fact that electricity represents the Group’s most significant environmental impact in terms of energy consumption. The opening of Stratford City added to the ongoing focus on identifying and implementing improvements across the national portfolio.
In particular, adjustments were made to lighting and heating systems in order to increase energy efficiency and reduce their associated loads. Around 20% of a typical shopping centre’s electricity consumption can be attributed to lighting, and during 2011 there were intensive reviews of non-essential lighting schedules and subsequent adjustments to eliminate unnecessary electricity use while maintaining the required lighting levels for security.
At Westfield London night time light switching was installed to ensure that only areas of the mall being worked on would be lit out-of-hours. In back of house areas for example, lights will turn off automatically after 30 minutes, although cleaning staff are to use a manual override when lighting is required. In addition the lower level car park lighting now drops down to a 10% light level when not in use. At Derby basement car park lighting has been replaced with dimmable fluorescent fittings, generating a 20% reduction in their electricity use. Other initiatives included installing microwave and dimmable lighting controls at the multi-storey car park which operates 24 hours a day, leading to a 35% reduction in consumption.
Other lighting initiatives include the replacement of older lamps at Merry Hill with more energy efficient LED fittings: the substitution of 250 watt tungsten external flood lamps for 10watt or 50watt LED varieties has generated around 60% reduction in electricity consumption for these particular fittings. There have also been targeted improvements to internal lighting, including replacing 50% of the 70watt down lighters in the food court along with the older 20 and 26 watt fittings in entrances and lifts with LED fittings. In addition, lighting controls in non-public access areas have reduced electricity demand by over 50% in these parts of the centre thus generating substantial reductions in utility costs.
Heating, venting and air conditioning systems are another key area where the Westfield UK team is working to reduce energy demand, and heating and cooling schedules have been reviewed to optimise systems where possible.
Air handling run times at Westfield London have been reduced, and smoke dampers modified to enable heat dump and reduce cooling demand. Modifications to gas heating control software have also generated a reduction in consumption.
Numerous initiatives collectively represent the Group’s desire to minimise waste and maximise efficiency.
At Merry Hill entrance lobbies and doors were upgraded from multiple sets of bi-parting and revolver units to mainly manually operated doors, typically reducing the cold air flow through the centre and subsequent demand for mall heating. Remedial works were also undertaken on the smoke vent compressed air systems including refurbishment of the control panel and replacement of the existing mechanical air pressure switches on the compressors with air pressure transducers thus allowing closer control of air pressure through the building management system. This improved monitoring and control facilitated an approximate 20% reduction in system operating pressure and subsequent compressor run time.
At Derby, thermal modelling was carried out with the aim of improving heating efficiency and reducing leakage, ensuring that all air handling unit controls were brought back to their original commissioned values. Recommended actions were identified to prevent cold air flows into the centre working against the heating: just one example was the installation of interim doors in an underpass entrance. The modelling also revealed an imbalance between the supply and extract rates of ventilation (heating and cooling) throughout the centre, with 30% more conditioned air being extracted due to a fundamental design issue. The excess energy used to maintain the centre’s temperature has now been addressed by the thermal modifications undertaken, including the shutting down of excess extract systems and the recalibration all of the air sensors.
The management of energy demand across Westfield’s UK portfolio has included numerous initiatives that collectively represent the Group’s desire to minimise waste and maximise efficiency, resulting in a significant reduction in impact on the environment.
Westfield Stratford City