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ammonia system, two compressors provide the refrigeration duty, with a third compressor on standby. On the medium temperature side , the system packs 825 kW of dut y, with up to 104 kW on the low temperature side. T h e c o n s u l t a n t a l s o l o o ke d i n to using an ammonia- only or a CO2 t r a n s c r i t i c a l s y s te m . I t w a s t h e a m m o n i a - C O 2 c o n f i g u r a ti o n t h a t came out on top, based upon a ‘balanced scorecard’ approac h of total e quivale nt war ming impac t ( TE WI), energy ef f iciency, capital cost, and colleague safety perspectives. “With a traditional distribution centre, whether for frozen or chilled, yo u r s ta r ti n g p o i n t is a m m o n i a ,” Arrowsmith says. “Here in Bromleyby-Bow, because this didn’t slot into the category of a distribution centre or a supermarket, we looked at it as a blank canvas.” “ We l o o ke d a t a m m o n i a o n l y, we to o k H F C s a s a b e n c h m a r k , a n d we looked at pure commercial CO 2 refrigeration ,” he explains. “ What we’ve installed here gave us the best balance between cost, energy and GWP – all the main measures you look at in an installation.”
Natural refrigerants ‘part of our DNA’ The use of natural refrigerants in Bromley- by-Bow is in keeping with S a i n s b u r y ’s w i d e r s u s t a i n a b i l i t y strategy. “Natural refrigerants are part of our DNA,” says Arrowsmith. The nationwide policy is to install CO 2 transcritical systems in all new Sainsbur y ’s supermarkets, as well as in major retrofits. Early CO 2 tr i a ls b e g a n i n 2 0 0 8 a n d a l l n e w supermarkets have been delivered with CO 2 since 2010. “If we deliver a new supermarket, it will be CO 2 ,” A rrowsmith says. “In 2017 we also made a step - change in convenience stores – ever y new c o nv e n i e n c e s to r e w i l l b e r o l l e d o u t u s i n g a n a tu ra l re f r i g e ra n t – primarily CO 2 .”
RIGHT Teams of pickers assemble customer orders in shifts.
“The first stop is that we always use a natural refrigerant,” he explains. “ The commitment is to natural refrigerants wherever possible.” S a i n s b u r y ’s i s p u t ti n g t h e HFC phase-down at the heart of its strategy for reducing operational carbon emissions by 30% absolute and by 65% relative (ve rsus 20 05) by 2020. The 2020 goal is par t of a broader target of an absolute carbon reduction of 50% by 2050. The supermarket giant operates 1,415 stores across the United K ingdom (May 2017 figure). When Accelerate E u r o p e w e n t to p r e s s l a s t September, it boasted 216 CO 2 transc r itic al su p e r mar ke ts in its por t folio. It also had eight convenience stores with natural refrigerants – seven w i th C O 2 b o os te r sys te ms , and one with a hydrocarbonsglycol configuration. Arrowsmith sees scope fo r hydro c ar b o ns to play a greater role in future. “Some of our more challenging Accelerate Australia & NZ // Summer 2018