Energy efficiency Supermarket case study


Table 2: Summary of energy use, emissions, costs and energy certificate performance showing the effect of improvements CO2


Electricity (kWh/yr)


Annual energy consumption 2009 Server room and bakery consumption as assessed


ANALYSIS RELATIVE TO CONSUMPTION EXCLUDING SERVER ROOM Consumption excluding bakery and server room


Total effect of short-term measures


Consumption following shorter-term measures Improvement from shorter-term measures


Total effect medium-term measures


Consumption as improved after all measures in Table 1 Improvement from all measures in Table 1


Effect of longer-term measures (Table 2) Installation of solar photovoltaic (PV) panels:


Consumption as improved including longer term measures Improvement from all measures including longer term


Supporting data Floor area for DEC calculation including server room and bakery Floor area for DEC calculation when server room and bakery is excluded Benchmarks adjusted & using DEC intensities (kWh/m2


) Unit cost (p/kWh)


Annual standing charges excluded from costs above CO2


intensities (kg/kWh) for this report generally CO2 intensities (kg/kWh) for DEC certification only


>


Biomass (kWh/yr)


1,019,343 200,920 116,884


0 (te CO2 /yr)


Cost (£/yr)


552 79,600 63 8,400


(kg CO2


Emissions /m2


DEC grade


EPC grade


173.1 83 / D 42 / B 20.3


902,459 200,920 65,040


10,000


837,419 190,920 - 7%


22,190


- 5% 0


815,229 190,920 - 10%


- 5% 1,600


813,629 190,920 - 10%


- 5%


490 71,200 35 5,000 454 66,200 - 7% - 7%


12 1,600 443 64,600 - 10% - 9%


1 0


800 0


442 63,800 - 10% - 10%


3,192 m2 3,093 m2


371 7.20


£640 0.537 0.550


tubes in surface-mounted luminaires. The replacement of these fittings with modern high-efficiency units cannot normally be justified through energy savings, but adaptor kits are now available that enable the tube and starter to be replaced with an electronic high frequency unit and a high output T5 tube. These tubes have the same light output as T8 tubes, but have much lower power consumption.


• Variable speed drives: the two existing air handling units in the main plant room provide heating and cooling to the shop floor using recycled heat from the refrigerators and recycled cooling from the shop floor with flow rates of 7 cu m/s and 3.5 cu m/s. Variable speed drives (VSD) on these units could be used to reduce air flows overnight. Using a VSD to control the extract air flow would


allow the additional winter heating or summer cooling to be reduced, but there would be no loss in overall ability as the full speed capability would still be available for normal use. It is estimated that the current annual fan usage is around 34,950 kWh and an average 50% reduction in flow rate during out of hours would give a saving of 17,400 kWh in the fan use with a similar saving in chiller use. It is difficult to quantify the heating load due to the steady consumption of the biomass boiler.


Conclusion While the Dartmouth store’s energy-saving building services installations have been shown to be effective, there is room for improvement. What is clear is that


48 CIBSE Journal October 2010 99


3.10 £640 0.025 0.025


the on-site wind turbine provides a significant energy- reduction facility that works well in its location. The analysis here also underlines the importance of


staff education and their continuing involvement in the processes available for keeping energy usage as low as possible within the necessary operations of a building. As well as providing organisational structures to


enable staff to become ‘champions’ of energy-efficiency and the need for ongoing energy management, the suggested changes also extend to providing shopfloor workers with more means to monitor and control their particular area of the building – such as installing sub- meters in the bakery. The findings and recommendations here will, hopefully, provide engineering professionals and low- carbon building assessors with insights that will help them to provide effective energy-efficient solutions in future. l


For the full survey report, go to the digital version of the October 2010 CIBSE Journal at www.cibsejournal. com For the previous CIBSE-commissioned survey published in CIBSE Journal, see the June 2010 edition, page 38, which is also on the website. To obtain a copy of CIBSE’s TM22: Energy Assessment and Reporting Methodology, visit www.cibse.org/bookshop


John Field and Alexandros Balaskas work for Power Efficiency.


www.powerefficiency.co.uk 206.5


158.3 76 / D 42 / B 11.4


146.9 71 / C 40 / E - 7%


3.9


143.1 69 / C 37 / D - 10%


0.3 0.0


142.8 69 / C 37 / D - 10%


www.cibsejournal.com


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