ENERGY EFFICIENCY BUILDING CASE STUDY
BUILDING SERVICES REFURBISHMENT MEASURES
The energy effi ciency features adopted during the refurbishment of the Shell Centre tower in 2010 comprised:
A chilled beam air conditioning system
New energy effi cient lift gear and controls
An effi cient, PIR-activated lighting system integrated into the chilled beams of the refurbished space that includes a light detector capable of adjusting the lighting levels and exploiting natural daylight
Air-handling systems including thermal wheels to recover energy from extract air
SYSTEMS IN PLACE
HEATING AND HOT WATER: Five low-pressure hot-water gas boilers, 4 MW each
CHILLED WATER SYSTEM: Served by up to six basement chillers cooled by river water. Operated by the building management system (BMS). Water from the River Thames is pumped via a pipeline into the building to act as a cooling medium for the main chiller plant condensers. When the river is cold enough it is fed direct to heat exchangers in the chilled water system to provide free cooling
AIR CONDITIONING: The tower has suspended chilled beams in offi ces served with circulating pumps located in the basement. The chilled beam system is integrated with heating, cooling and lighting sensors. The wings are served by a ceiling radiant panel system providing heating and cooling to offi ces
VENTILATION: The tower and wings have air handling units. Ventilation plant is controlled by the BMS
LIGHTING: See main text.
John Field checks the Shell Centre heat exchanger
equipped with effi cient PIR controls with motion detectors in open-plan offi ces, meeting rooms and other areas. The delay time for these controls is 20 minutes. Lighting consumption for these areas is assessed to be 144,000 kWh of electricity per year. Reducing the delay time to 10 minutes would produce a saving of 18,300 kWh per year, cutting the annual cost by just over £1,000. This would also cut CO2 emissions by 10 tonnes per year.
Other measures Building management system: A review of the BMS would also yield savings. The aim is to review schedules and settings of the BMS and to update these to provide lean operation without reduction in service levels when the building is occupied. It is expected that information on customer and staff requirements and feedback will be available from the staff engagement initiative (see below). Staff make sure that the plant goes on as late as possible and goes off as early as possible. A price of £10,000 is budgeted for initial investigation, review and updating of settings in the headings above. In addition BMS system and control interface upgrades are budgeted at £25,000. The BMS schedule and operation review is assessed to yield 444,000 kWh of electricity savings and 564,000 kWh of gas savings – together yielding annual cost savings of £56,000 and payback within one year. Staff engagement: This is an exercise
aimed at training and engaging specifi c staff to promote and oversee energy effi ciency in the use of Shell Centre by its occupants. Increased levels of energy conservation awareness among the staff have been developed, and staff are expected
36 CIBSE Journal May 2011
to switch off lights and monitors once they leave the building. Regular checks are carried out by security staff to ensure that lights and monitors are switched off. The staff engagement initiative is
assessed to save 296,000 kWh of electricity and 376,000 kWh of gas per year, or £38,000 annually. Associated CO2 emissions savings are 228 tonnes per year. Voltage power optimisation: A feasibility
study into using VOP is recommended. VOP is the managed reduction of voltage supplied to the site, to reduce energy use, power demand and reactive power demand.
Conclusion The effi ency measures adopted at Shell Centre in 2010 are estimated to produce a major reduction in energy use and carbon emissions (see Figure 1). Additions and enhancements to these action are predicted to signifi cantly further increase these savings (Figure 2). The fi ndings and recommendations outlined here will, hopefully, provide engineering professionals and low carbon building assessors with insights that will help them to provide effective energy effi ciency solutions in future. For CIBSE, the lessons learnt will provide key insights for the wider engineering community involved in the built environment.
GET THE FULL REPORT
For the full survey report, go to the digital version of the May 2010 CIBSE Journal at www.
cibsejournal.com Previous survey reports can be found with February 2011, October 2010 and June 2010 digital editions. To obtain a copy of CIBSE’s TM22: Energy Assessment and Reporting Methodology, visit
www.cibse.org/bookshop
www.cibsejournal.com
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