CIBSE GUIDANCE TM54
end-uses. This energy use can be substantial: in one case study it was found that 60% of the energy use, that for the server room and the catering, was across just 3% of the floor area. This more than doubled the operational energy use over the design estimates. The guidance explains how to run scenarios and recommends that the sensitivity of different options be tested to determine the potential range of performance. Figure 3 shows a sensitivity analysis of the TM54 case study building. This indicates that a 4% change in the chiller efficiency makes a very small difference in overall energy use, whereas reducing the operating hours by one hour per day provides an 8% reduction, and implementing a weekend shutdown cuts energy use by 19%.
Presenting the results The guidance then provides examples of how to present the results by using different
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scenarios to reflect the level of uncertainty of the estimates. The results of the calculations, the sensitivity analysis and range of scenarios can be presented as simple graphs showing the overall results (figure 4) and broken down into the different end-uses (figure 5). In addition to helping designers to estimate performance more accurately, these results will highlight any areas where actual energy use may be higher than a typical building, allowing this to be considered at the design stage. As Davies says: ‘The aim of TM54 is to provide practical guidance to enable the buildings we are designing, or redesigning, to deliver the energy performance that the owners and operators expect, and to reduce their demands for energy in the years to come.’ CJ
l DAVID CHESHIRE is regional director at Aecom and was a principal author of TM54 along with ANNA MENEZES who is a research engineer at Aecom
The guidance explains how to run scenarios and recommends that the sensitivity of different options be tested to determine the potential range of performance
Worst case High-end Mid-range
Low-end TM54 LAUNCH
TM54 will be launched on 25 September at Prince Philip House, 3 Carlton House Terrace, London. Chaired by CIBSE President George Adams, the event will include an introduction from principal authors, David Cheshire and Anna Menezes, followed by a presentation from Morwenna Wilson on how Argent have been working to close the ‘performance gap’ in their portfolio. For more information go to:
www.cibse.org/tm54/launch
TRAININGEVENTS
Heating (gas)
Hot water (gas)
Cooling Fans and
pumps Figure 5: Presenting the results of different scenarios
Lighting Office equipment
Lifts
The following events taking place at CIBSE HQ in Balham are relevant to TM54: 6 sep 2013 Energy efficiency building regulations: part L 11 sep 2013 Energy strategy reports 24 sep 2013 How to specify a ground source energy system For more information go to:
www.cibse.org/ training
38
CIBSE Journal September 2013
www.cibsejournal.com
Annual energy consumption (kW·h/m2)
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