could be undertaken at the site. These focused mainly on further improvements to the lighting and building-management systems, but also included suggestions for enhancing existing measure to engage staff with the drive for improving efficiency and cutting waste. Estimated energy and cost savings, together with ‘payback’ periods, are also provided with the recommendations – see Figure 2. Taken together, the measures above
would produce estimated annual electricity and gas savings respectively of 1.1m kWh and 973,200 kWh, with a total annual cost saving of £128,100. The cut in carbon emissions would total 770 CO2 tonnes per year. Payback periods for the £118,240 total cost of these measures range from a few months to three and a half years. Overall, this range of measures would be expected to raise the Energy Performance Certificate rating for the Shell Centre from D to C.
Lighting The recommendations for further action focus mainly on improvements to lighting efficiency, as follows.
www.cibsejournal.com
Wing offices: The current T8 lighting
fittings have a rated output of 36W and a calculated lighting level of 12.6 W/sq m. If this type of lighting is replaced with T5 fluorescent tubes rated at 28W, this will result in an improvement lighting level of 9.5 W/sq m. The calculated savings are 200,000
kWh and £18,000 per year. The associated saving in carbon dioxide emissions is 107 tonnes per year. Controls: The Shell Centre tower is
Benchmarking Comparison of site’s 2009 energy data Metering data are uploaded
Electricity consumption is recorded by two half-hourly electricity meters. In addition there are 17 non-half hourly sub-meters dedicated to metering the energy consumption of the boilers, chillers, the tower and the wings consumption. Gas consumption is recorded by three non-half hourly meters, one for the boilers, one for the main kitchen and one for the tower kitchen.
to the supplier’s web portal and can be interrogated remotely by the Shell Centre staff with appropriate user name and password. During Shell Centre Tower
renovation, local meters were installed on each floor to monitor the lighting, the small power and the UPS consumption individually. Energy costs for Shell Centre in 2009 were £1,896,000,
Additional changes recommended by an energy review included further improvements to lighting systems
comprising £1,332,000 for electricity and £564,000 for natural gas. Energy supplies were 14,800,000 kWh of electricity and 18,800,000 kWh of gas. The assessment of
performance indicates that the building’s emissions figure of 106 kgCO2/sq m is 47% worse (higher) than the Good Practice benchmark (72 kgCO2/sq m) and 20% better (lower) than the typical benchmark.
May 2011 CIBSE Journal 35
© David Osborne / Alamy
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