feature
>>> SEAN McGOWAN REPORTS
IGA greens its aisles
Metcash Trading Limited, the company supporting your local IGA
supermarket, mightn’t be the biggest player in Australia’s supermarket
world but it fights above its weight when it comes to energy efficiency
among the aisles, as Sean McGowan reports.
You would think being independently owned and
operated would put IGA supermarkets at a disadvantage
when it comes to reducing its ecological footprint. After
all, it’s the big players such as Coles and Woolworths that
seem to get the lion’s share of eco-publicity.
Although the ability to control and implement change
at store level mightn’t be the same, Metcash Trading
Limited, which both markets and distributes for IGA
Supermarkets, is still achieving significant breakthroughs
in energy efficiency, with many stores reducing their
ecological footprint (and their electrical bills) through
behavioral change at no or low cost.
“We want to help our customers (store owners) save
money and improve their environmental performance
through improved efficiency across all areas of energy
usage, from refrigeration and store design to heating,
water usage and lighting,” says Louise Rhodes, senior
sustainability adviser for Metcash.
As such, the company is working with its store owneroperators across a wide range of initiatives, with a
strong focus on resource efficiency. These include the
investigation of power factor correction, correct location
of plant room in relation to refrigeration fixtures, use of
automated night blinds in open cases, and more efficient
case lighting such as LED lighting systems, which show
an energy usage reduction of approximately 60 per cent.
But it is in-store refrigeration and air conditioning where
Metcash and its IGA customers are making significant
headway through outside-the-box thinking.
“The refrigeration and air conditioning plant in
supermarkets generally represents at least 60 to 70 per
cent of energy usage, so to reduce that direct energy
cost is an immediate focus and of greatest benefit at this
stage,” Rhodes says.
Rack with a difference
IGA Supermarket’s rack systems are different to the norm,
comprised of a greater number of smaller compressors
(up to seven are used as opposed to the more standard
three or four), while the lead compressor is on a variable
speed drive (VSD).
According to Peter Hoyne, mechanical engineering manager,
the benefits of this type of configuration are three-fold.
Firstly, he says, multiple smaller compressors (to
approximately 56m² per hour) reduce the potential for
disruption to the entire system through redundancy. It
also lessens secondary impacts such as potential stock
loss through system failure.
12 HVAC&R Nation “Smaller displacement compressors create far less
vibration from discharge pulsation on the rack,” he says.
“This reduces the potential for leaks from fractured
discharge lines. We’ve found the average system gas
leakage is reduced from approximately 25 per cent per
annum to around 5 to 10 per cent per annum,” he says.
This configuration also allows the VSDs to be set to
overspeed the lead compressor to 60Hz, which saves
cycling an extra compressor on.
VSDs are also installed on the condensers to maintain a
constant condensing temperature at the most efficient
input. By using VSDs on compressors, condensers
and evaporators as opposed to slide valves on screw
compressors, or cylinder heads unloading on a
reciprocating compressor, potential energy savings of 20
per cent are created.
“We also use electronic evaporator pressure regulators
to control temperatures of cabinets and cool rooms. This
allows us to operate the plant at the highest possible
suction temperatures,” Hoyne says, adding that all these
initiatives are geared to be achieved at a viable initial
cost to the independent owner-operator, with a payback
in energy savings within one to two years.
Seeking an alternative
While Metcash keeps an eye on the burgeoning use
of natural refrigerants in supermarket environments,
Rhodes says it is the order of action that is paramount
to the company’s Draft Integrated Carbon Management
Plan – a key plank to its corporate governance on
sustainability. This places measurement, avoidance and
reduction of energy consumption through modification
and recovery at the top of its hierarchy system.
“This hierarchy of action emphasises low or no cost
change, then those with a fast payback, before moving
on to initiatives which have a longer payback period. This
hierarchy was adapted from EPA Victoria,” she says.
Peter Hoyne
refrigerant trans-critical system installed in the southern
hemisphere at Drakes Foodland, a Metcash-supported
supermarket located at Angle Vale, South Australia.
“The unit runs on no other refrigerants, unlike our
competitors’ systems, which utilise hybrid systems. The
unit was installed by contractor Hill Equipment and won
a prestigious Refrigeration Installation of the Year award
at the CoolWorld industry awards in April,” he explains.
Through this installation, Metcash has learned that
there is a premium cost of 50 to 100 per cent over the
standard IGA-designed CO2 cascade system, delivering a
power reduction of up to 10 per cent and a reduced CFC
charge, which is 20-30 per cent of a standard system.
“This makes the capital outlay quite steep for small
independent stores, with long payback periods,”
Hoyne says. “Natural refrigerants will have a role, but
resource efficiency is the logical first step to improve the
performance of existing plant.”
For the group’s smaller stores, the level of investment
required to move into alternative or natural refrigerants is
generally prohibitive.
Co-generating
heat and sales
“As our smaller stores only have small conventional
refrigerant charges, we don’t believe it is cost-effective
for them to change to alternative refrigerant,” says
Hoyne. “Again, we’ll concentrate on keeping refrigerant
charges to a minimum.”
Co-generation is an important element of the company’s
energy-efficiency program, whether through heat
reclaim or cold aisle air return. This allows stores to
supply a considerable amount of their own heating and
air conditioning through recycling the heat and cold air
produced as a by-product of the refrigeration system.
Although Hoyne says the company would consider
CO2 trans-critical technology in its larger stores, it is
monitoring the success of the first, 100 per cent natural
November 2008
The cold aisle return air systems collect the overspill of
cold air from open refrigerator cases and redistribute it
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Produce case
around the store through the air conditioning system,
contributing up to 60 per cent of the store’s total air
conditioning requirements.
Remarkably, this type of system also aids in improving
sales and customer comfort, particularly in dairy and
meat sections where customers are now seen to stay
longer at the cases than they otherwise would because
of the cold air in the vicinity of the case.
“The design we are looking at is aimed specifically at
minimising the issue, being lightweight, frameless and
easy to open without rubber seals,” Hoyne says. “They
are also relatively inexpensive to implement, being easily
retrofitted to existing cases.”
Aside from seeking efficiencies in refrigeration and
air conditioning plant design, Metcash is seeking cost
savings through smarter lighting systems and water
efficiency.
The use of LED lighting in cases and glass door freezers
can reduce energy use from 60 watts per flouro tube
to 20 watts for LED lights, representing a significant
energy saving for stores. This higher efficiency lighting is
becoming standard specification for all new IGA cases.
Similarly, Metcash is using heat reclaim from plant
equipment to supply up to 100 per cent of the store’s
heating, and approximately 60 per cent of its hot water
requirements. And according to Hoyne, the company is
seeking further opportunities for recovery and reuse.
“The Stirling Engines is one type of technology we are
interested in investigating. Utilising the waste heat from
the refrigeration plant, the system then converts it to
mechanical energy to direct a generator that can supply
power back into the refrigeration plant, driving antisweat heaters of fan motors,” explains Hoyne.
Working around an impulse
Hoyne says the company is also investigating options
such as putting doors on open display multideck cases
to reduce refrigeration load, with some pilot stores being
retrofitted in the near future.
The idea has traditionally been met with concerns
around the potential to create a barrier between the
customer and the product, resulting in a reduction
in impulse buying, but he believes that savings in
energy costs along with consumer appreciation of the
environmental benefit will neutralise any impact.
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Low temperature rack with liquid line sub cooler
November 2008 HVAC&R Nation 13
Glass door freezer
The company is also moving towards harvesting rain or
treated storm water for use in cooling towers.
“Given each square metre of roof yields one litre of
water per one millimeter of rain, a 10,000m² will yield
around 6,400,000 litres per annum based on Melbourne’s
average rainfall. With the cost of water expected
to double over the next five years this represents
considerable cost savings,” adds Hoyne.
The drive for efficiency doesn’t stop at store level, with
distribution centres and warehouses also undergoing
change.
future new and refurbished distribution centres,
with payback periods typically between one
and two years.
“We have recently implemented a very advanced smart
lighting system in our Crestmead distribution centre.
It cuts down around 75 per cent of our lighting usage
in daylight hours,” explains Rhodes, adding that the
company is investigating LED lighting initiatives in all
Metcash is also rolling out more efficient refrigeration
plant through a refurbishment and retirement program,
with new warehouses at Laverton and Crestmead using
ammonia in their plants.
“Ammonia, being a natural refrigerant, has no global
warming ramifications, however, it is a toxic gas so it’s
unsuitable for supermarket application,” says Hoyne.
How far can it go?
According to Metcash, green supermarkets are set
to become the norm, because it is not only good for
business – it is also what customers are increasingly
requesting.
“We certainly see advantageous marketing potential
for stores employing greener initiatives. By harnessing
the considerable consumer goodwill towards
environmentally friendly operations and actively
promoting themselves as ‘green’ stores, they can
develop a positive point of difference in the market and
greater customer loyalty,” suggests Rhodes.
Rhodes points to legislative change, rising energy costs,
and an increasing public awareness as drivers for the
future of green supermarkets.
“Our multitude of upcoming sustainability initiatives,
both for Metcash and how we propose to support
our customers and supply chain, will be included
in our upcoming sustainability strategy, which will
outline our strategic direction towards sustainability
and good corporate social responsibility.” s
Compressor motor soft starter
14 HVAC&R Nation November 2008
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