Energy-efficient cool rooms and refrigeration

FARM ENERGY INNOVATION PROGRAM - ENERGY IN SHEDS
Energy-efficient cool rooms and refrigeration
Chilling and refrigeration can account for more than half of a
farm’s energy use. Cold chain technology has improved markedly
over the past decade and the range of opportunities for farmers
to save energy has expanded. This fact sheet provides an outline
of the energy-saving opportunities in cooling and refrigeration,
and details areas in which upgrades can improve the quality of
your produce and its farm-gate value.
The cold chain
New technologies in refrigeration allow for greater control
over the quality of products and may enable significant energy
savings as well.
Innovative methods, such as quick cool-down of meat
products and pre-cooling of fruit and vegetables, can help
farmers make energy savings along the ‘cold chain’, as
illustrated in Figure 1, while maintaining product quality and
food safety standards.
Figure 1: The ‘cold chain’ in agriculture (Energetics 2013).
For many farmers, refrigeration makes it possible to get fresh
produce to the market. Temperature control is critical, as are
the control of humidity, water and air movement. Many crops
also have short growing seasons, requiring products to be
managed effectively at every stage in the cold chain: the
quality of the end product is only as good as the weakest link
in the chain.
Quick wins
Prevent heat from entering your refrigeration system and
you will save money.

Look at shading, positioning and the design of your
facility. Does your refrigerator receive direct sunlight?
Consider ways of avoiding heat gain from sunlight.

Reduce the temperature of products to be placed in
storage by picking produce at night or early in the
morning. Alternatively, an array of pre-cooling
methods, such as hydro, vacuum or forced-air cooling,
could be considered.

Organise restocking so as to minimise the number of
times you need to access the coolroom.

Inspect the seals, insulation and door alignment of
refrigeration units regularly. Seals wear and can be
damaged, compromising food safety and wasting
energy. Look at where forklifts and vehicles may
damage the polystyrene shell of your coolroom and
consider taking steps to prevent such damage.

Install insulated coolant pipes to limit heat
absorption from the surroundings.

Inspect and clean heat exchangers to improve the
performance of your refrigeration system. Ensure that
dust and spider-webs are not clogging the fins; that
no grass is growing in front of the outside exchanger;
and that products are not blocking the fan inside.
Your goal is to maintain a clear, unobstructed area for
at least one metre in front of and behind the coil.
In addition to lower energy bills and improved product quality,
an investment in energy-efficient refrigeration technology may
result in opportunities to differentiate your produce from that
of your competitors.
This information sheet will guide you through the refrigeration
process, discussing points in the process at which you can save
energy and money without sacrificing quality control.
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FARM ENERGY INNOVATION PROGRAM - ENERGY IN SHEDS
Energy-efficient coolrooms and refrigeration
Assessing opportunities
In a typical refrigerated warehouse, 15 percent of electricity
use is for running pumps, motors, fans, conveyors and lighting
systems, five percent is for sanitation and cleaning, and the
remaining 80 percent is used for cooling, freezing and
refrigeration.1
Investment in energy efficiency is not only about technology
upgrades. Innovation can be a great marketing tool and a
driver of cost reduction. Engaging and working closely with
customers can give you an edge over your competitors. For
example, customers may place a premium on the temperature
of produce being within a specified range before delivery.
There may also be different – and more energy-efficient –
ways to meet regulatory food safety requirements.
When assessing opportunities for boosting the energy
efficiency of your cooling/refrigeration system, gain a better
understanding of your system by considering the following:





What equipment do you already have? How old is it?
Many studies suggest that units more than 10 years old
are worth replacing. This also applies to control systems.
What’s your current electricity use? Measure your
consumption, either by the whole system or by individual
components. Ideally these will be sub-metered, but plugin meters are also available. Alternatively, an electrician
can install a temporary meter. Let the meter run for a
week and work out your average use.
What lights do you have? How are they controlled?
How are your seals and insulation? Are the door seals of
all cooling and refrigeration units in good order? Inspect
the insulation of your cool rooms, paying particular
attention to the edges and joins.
Is it better to replace the whole cooling/refrigeration
unit or just components of it?
Once you have a basic understanding of the refrigeration
system in your business, the next step is to compare various
viable energy opportunities and choose those that best suit
your operation. You should be familiar with how refrigeration
uses energy. Electricity is used principally in compressors, fans
and lights, as illustrated in Figure 2.
Technology across the agricultural sector varies from ‘integral’
units similar to those of the typical residential fridge, to mobile
refrigerated transport and large coolrooms in distribution
centres and on farms. Even with this range of scale, certain
technological components – a compressor, an evaporator and
a condenser, all linked by pipes – are common to all systems.
Figure 2: Energy use by refrigeration system components2.
As the technology is the same, the principles of efficient
operation also apply. How energy is used and moved around a
refrigeration system is illustrated in Figure 2. Every arrow
represents a place in the system that can be made more
efficient. The blue arrows show where electricity is used, the
red arrows show heat flows.
Figure 3: Energy flow through a refrigeration system3.
Typical refrigeration systems will have two heat exchangers:
one inside the fridge and one outside it. To maintain a
constant temperature, the compressor must remove heat at
the same rate as the rate at which it enters the cabinet.
Reduce the rate at which heat enters the cabinet and you
reduce all electrical usage.
Typical sources of heat load in coolrooms are the temperature
of produce before it enters cool storage, forklifts, air
exchanges, and heat transfer through the building shell.
Typical energy savings opportunities, applicable to the ‘whole
of system’ and to key energy-use components of the system,
are highlighted below.
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FARM ENERGY INNOVATION PROGRAM - ENERGY IN SHEDS
Energy-efficient coolrooms and refrigeration
Technology innovation delivers energy saving
Many cost-effective energy savings opportunities exist in
refrigeration systems, particularly in large systems such as
coolrooms. Figure 4, below, illustrates the average payback in
years and percentage reduction in energy use by the system or
component to which the energy savings measure is applied.
Energy savings measure
Energy
savings1
Payback
Night blinds
24–29%
0.28
High-efficiency compressor
4–10%
0.74
Inert gas-insulated glass doors
8–10%
0.74
Glass doors/lids
50–59%
1.33
Electronically commutated
evaporator-fan motors
5–19%
1.37
Electronically commutated
condenser-fan motors
3–8%
1.37
Variable speed drive (VSD) fitted
to the compressor
9–19%
1.54
High-efficiency lighting
<19%
1.59
Insulation (+25 mm)
1–6%
3.09
Energy management system
and/or controls
<60%
varies
Beyond changing the fan motor, you can upgrade the fan
attached to the motor for very little cost. New, stiffer and
lighter plastics push air more efficiently and often, one of
these can be fitted to your existing motor.
Larger systems may also benefit from a variable speed drives
(VSDs) or the addition of a variable speed controller. VSDs
reduce the electrical load during low load periods, while
controllers can be fitted to existing motors to reduce the
current use during start-up.
Refer to supplementary paper, VSDs on fans.
Figure 4: Energy savings opportunities in order of payback.
Typical savings and paybacks will vary depending on the
efficiency of the system being replaced and the choice of
upgrade. Consequently, payback periods may be shorter or
longer (e.g. many studies suggest payback periods of under
a year for high-efficiency compressors).
Motors, compressors and fans
The big change in refrigerators over the past decade is an
increase in the widespread use of electronically commutated
(EC) motors. These motors use much less energy than
traditional copper-wound induction motors.
A typical refrigeration system might have three motors: one
for the compressor and one each for the evaporator and the
condensor. Replacing these in an existing system could reduce
energy use by half. System age is a good indicator and, in
general, anything 10 years or older2 is unlikely to be an EC
motor. Buying a new complete system with EC motors could
reduce your energy use by even more.
1
Energy savings are expressed as a percentage of savings against the equipment
load or application load, whichever is applicable.
2
Typically, a compressor comes as a single, sealed unit. So the
compressor and motor that drives it need to be replaced at the
same time. These are ‘hermetically sealed’ units. Advances in
both motors and compressors should make this a high-value
opportunity. The savings from upgrading the compressor can
be determined using information from suppliers. Work out
how much energy your compressor uses now to supply a given
pressure, then compare that figure to the energy a new
compressor supplying the same pressure would use.
If you are unsure of a motor’s age, the motor plate should indicate whether that
motor is a new EC; otherwise, an electrician or mechanical fitter should be able to
help you.
Lighting
Significant advances have occurred in lighting with
the introduction of LEDs. If your lights look like this
traditional incandescent bulb, you can be certain that
upgrading them to high-efficiency fluorescent bulbs or LEDs
will save you money and improve the reliability of your lights.
LED solutions are available for a range of applications, from
illuminating warehouse high-bays to providing cost-effective
strip lighting for refrigeration. The payback period for LED is
typically longer than for other energy-efficient lighting but a
payback period of less than four years is still common.
If you are calculating the savings that these new lights can
deliver, remember that lights inside a refrigerated space also
contribute heat. LEDs are more efficient because they emit
less heat. The impact of this will usually be small, but removing
that heat load will make the whole system more efficient.
Refer to supplementary paper, Lighting.
Control system
The control system itself uses very little energy, but it controls
how much energy the other components use, which makes it
an important link in the system.
Modifications as simple as ensuring temperature settings are
correct can lead to significant savings over time, with one
degree Celsius of temperature adding about five percent to
the energy use. More advanced control systems can provide
more accurate control of temperature, lighting and fans,
leading to savings throughout the system.
Refer to supplementary papers, Refrigeration – Variable
temperature control and Refrigeration – Variable head
pressure control.
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FARM ENERGY INNOVATION PROGRAM - ENERGY IN SHEDS
Energy-efficient coolrooms and refrigeration
Replace the whole system?
Small integral systems similar to residential refrigerators
and/or deep freezers close to 10 years old might be
worth replacing. Some of these appliances will still
have Energy Rating stickers attached and these are
a great means of determining the system’s energy
use. If no such stickers are attached, investigate
ways of measuring the system’s energy use
directly, using a plug-in meter or with an electrician’s help.
Many businesses are now taking steps to reduce their
exposure to these prices by shifting to lower-GWP refrigerants
such as carbon dioxide and propane. It is a complex area but
one worth considering when you’re replacing equipment, as it
could lead to significant savings over the life of the equipment.
Applications
GWP
R22
Being phased out
1,810
R134A
Air-conditioning and highertemperature refrigeration
1,430
Work out how much energy the system uses in an average
year. Once you have this, you can compare this energy use to
those of new units, which have to be pre-tested and must
meet Australian Standards. On its energyrating.gov.au website,
the federal government has calculators that allow you to input
your electricity price and compare various units to see which is
likely to save you the most money.
R407F – a blend of R32,
R125 and R134a
A wide range of refrigeration
(designed as a swap for
ozone-depleting R22)
1,705
R404A
Low temperature refrigeration
3,784
R290 – propane
Typical in ice-cream freezers,
but appropriate for a wide
range of refrigeration
3.3
Replacing coolrooms and other large, remote compressor
refrigeration systems is much more complicated, with the
price of upgrading driven by the labour costs associated with
piping and installation as well as those of the components
themselves. In cases like these, you will be better served by
analysing the energy-using components individually than by
measuring whole-system use. Apply the rules above for
motors, fans, compressors and lights to see improvements
across the whole system.
R600a – isobutane
Small refrigerators
3
R744 – carbon dioxide
A wide range of refrigeration
1
To get more out of your existing large refrigeration or
coolroom system, consider the following:



Analyse the energy-using components individually
rather than measuring the whole-system use. Apply the
rules above for motors, fans, compressors and lights to
see improvements across the whole system.
Change the timing of when the refrigeration system is
used. This can impact the cost, depending on our
electricity tariff structure. This can be difficult with
perishable goods, but is feasible with large glycol-water
systems like those used in dairies or poultry processing.
Inspect for damage to the wall panels. In cool rooms and
other large installations, the panels are often made from
polystyrene, a terrific insulator, but prone to physical
damage. Periodically inspect the outer and inner
perimeters for damage that may allow air flow into the
coolroom.
Refer to supplementary paper, Refrigeration – upgrade or
replace degraded compressor.
Consider refrigerant gases when upgrading
There are no opportunities to change the refrigerant of an
existing system to another which will improve performance.
However, under current Australian law, refrigerants are
impacted by the amount they contribute to global warming,
determined by their Global Warming Potential (GWP). Carbon
dioxide, the most basic greenhouse gas, has a GWP of one. So,
one tonne of carbon dioxide attracts one unit of carbon price,
about $23. But for R404A, a common low temperature
refrigerant, carbon price per tonne is 3,784 x $23 = $87,000.
Designation
Table 1: GWP and the application of various refrigerant gases5.
Further information
Farm Energy Innovation papers
Refrigeration – Variable temperature control
Allowing and planning for temperature variation within
refrigeration can increase energy savings.
Refrigeration – Variable head pressure control
Adjusting head pressure set points allows for optimal
condenser operations and energy savings.
Refrigeration – Insulation on tanks
By ensuring that refrigeration tanks, coolroom storage and
other climate-controlled areas are tight and well insulated,
farmers can reduce cooling requirements and save energy.
Refrigeration – Upgrade or replace degraded compressors
Upgrading or replacing refrigeration compressors is an energysaving opportunity.
Variable speed drives in agriculture
Fitting variable speed drives (VSDs) to motors can reduce their
energy use. This includes evaporator and compressor fans in
refrigeration.
Food safety effects of damaged fridge seals
NSW Food Authority, NSW food safety laws:
www.foodauthority.nsw.gov.au/industry/food-standards-andrequirements/legislation/#.Ufr8CG1aeTM
NSW Food Authority 2008, potentially hazardous foods:
www.foodauthority.nsw.gov.au/_Documents/science/potentiallyhazardous-foods.pdf
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FARM ENERGY INNOVATION PROGRAM - ENERGY IN SHEDS
Energy-efficient coolrooms and refrigeration
Brewer, SJ, 2011, ‘Damaged and Soiled Refrigerator Seals
(Gaskets) from Commercial Food Premises: A Potential
Reservoir for Food Pathogens’, Bioproducts Technology
Consultant
www.bptc.co.uk/Fridge_Seals_Food_Pathogens/Report
Case examples
 A typical vegetable coolroom, designed to handle
between two and six pallets.
www.omafra.gov.on.ca/english/engineer/facts/98-031.htm
Energy-efficient refrigeration technologies
Office of the Environment and Heritage, 2011, Energy Saver –
Technology Report: Industrial refrigeration and chilled glycol
and water applications, New South Wales
www.environment.nsw.gov.au/resources/sustainbus/110302E
SRefrigRprtLowRes.pdf
Queensland Government, 2010 Refrigeration Efficiency – U5
www.ecoefficiency.com.au/Portals/56/factsheets/foodprocess
/utilities/ecofoodutil_fsu5.pdf
Mary’s Free Range Chicken product website
www.maryschickens.com/Airchilled.htm
Federal government, Industry Tourism Resources, 2003, A
guide to energy efficiency innovation in Australia wineries,
Australian Federal Government
www.ret.gov.au/energy/documents/best-practiceguides/energy_bpg_wineries.pdf
 South Queensland fruit and vegetable supplier talks about
the importance of temperature control and the additional
benefits of humidity control.
http://www.crq.net.au/case-study-keeping-it-fresh
 Simplot at Bathurst in NSW discusses some of the more
complex compressor upgrades and system modifications
available for large systems.
www.lowcarbonaustralia.com.au/where-we-work/simplot-bathurstenergy.aspx
References
1.
Australian Federal Government, 2013, Product Profile –
Commercial Refrigerated Display and Storage Cabinets,
E3 Committee, Department of Resources, Energy and
Tourism.
Management of packing sheds and coolrooms
Growcom and the Queensland Government, Land and Water
Factsheet. Energy efficiency: Packing shed and cool room,
Queensland Government
www.growcom.com.au/_uploads/64154EE_Packing_shed_and
_cool_room.pdf
Alberta Agriculture and Rural Development, Fresh Fruit and
Vegetable pre-cooling for market gardeners n Alberta
www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex74
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NSW Farm Energy Innovation Program © NSW Farmers Association 2013
NSW Farmers gives no warranty regarding this publication’s accuracy, completeness, currency or suitability for any particular purpose and to the extent
permitted by law, does not accept any liability for loss or damages incurred as a result of reliance placed upon the content of this publication. This publication
is provided on the basis that all persons accessing it undertake responsibility for assessing the relevance and accuracy of its content. The mention of any
specific product in this paper is for example only and is not intended as an endorsement. This activity received funding from the Department of Industry as
part of the Energy Efficiency Information Grants Program. The views expressed herein are not necessarily the views of the Commonwealth of Australia, and
the Commonwealth does not accept responsibility for any information or advice contained herein.
Head Office: 02 9478 1000
Energy Info Line: 02 9478 1013
www.nswfarmers.org.au
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Content produced with
assistance from Energetics
www.energetics.com.au
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