By Ilana Koegelenberg
Where are we going (locally and globally) in terms of commercial supermarket refrigeration installations and what are some common mistakes made that can be avoided?
As we tend to focus more on the ‘HVAC’ side of HVAC&R than the ‘R’, this year we are throwing a couple of refrigeration features into the mix to see what is happening in the booming industry.
According to this graph by Danfoss, looking at data from 10 000 CO2 installations and 150 ejector installations, they are confident that CO2 systems will save more energy than R404A systems.
Image credit: Danfoss
I had a chat to various key stakeholders to get a better understanding of the dos and don’ts of supermarket refrigeration. Engineers, contractors, manufacturers, and even end-users got involved to help paint this picture of an industry so vast, so progressive, that is hard to keep up with.
“We’ve noticed that CO2 has definitely become one of the preferred refrigerants to use in supermarkets in South Africa.”
If I had to pen an executive summary, it would be: we are keeping up with technological advances and international trends, but not in terms of skills; and natural refrigerants are the belle of the ball for sure.
Supermarkets are among the greatest commercial energy consumers, explains Roy Naidoo, area sales manager at Danfoss South Africa. For retailers, the energy expense is second only to labour when looking at operational expenses and typically accounts for over 3% of turnover in an increasingly competitive business where profit margins average below 2%. Refrigeration and heating together are the greatest energy consumers. “Although great savings have been achieved in recent years, much more is possible,” says Naidoo.
Transcritical CO2 systems are becoming more widespread in South African supermarkets. Taken at Woolworths Kyalami.
Image credit: Ilana Koegelenberg
The biggest trend seems to be a move towards more energy-efficient installations, as with most of the construction industry. This is achieved in many ways.
One of the most noticeable ‘trends’ is of course the change of refrigerants. Refrigerants began to change with the phase out of R22, and the norm is mostly R404A (with R507 being considered an alternative), R134A, and R744 (CO2), says Merrick Smith, managing director of ProActive Refrigeration. The use of R404A as both a medium-temp and low-temp refrigerant is commonplace, more so than R134A, and is possibly attributed to how many existing R22 plants were converted to R404A. This may be a factor in why even new plant specifications are often designed as R404A plants for medium temp, as opposed to R134A.
CO2 is the talk of the town it seems and has been in use in supermarkets for a decade now. Many used a subcritical low-temp CO2 system in conjunction with a R134a or R404A medium-temp system over recent years and have now made the change to both systems being CO2 by having transcritical plants installed, explains Smith. “With smaller retail groups also considering transcritical systems, we may soon have the market split into those groups embracing CO2 and those that don’t at all.”
“We’ve noticed that CO2 has definitely become one of the preferred refrigerants to use in supermarkets in South Africa,” says Maurice Robinson, director: sales and marketing at Sphere. The demand has increased for these kinds of systems.
“Forward-thinking retailers in warmer climates, like South Africa, are moving towards CO₂ solutions that can support them to save up to 20% on energy bills,” says Naidoo from Danfoss. “Compared to traditional HFC refrigerants, the effect of CO2 on the climate is up to 4 000 times less. So, not only will these retailers save on costs, but they will dramatically reduce cooling-related emissions.”
Alex Kuzma, head of engineering services at Woolworths’s real estate department, can vouch for this too. “There is a slow but definite swing towards natural refrigerants and energy-saving technologies,” he says. “The payback times for these technologies are reducing greatly as a result of spiralling energy and HFC gas costs.”
Perspex and glass doors on chiller cabinets can create large savings and they are gaining popularity.
Image credit: Ilana Koegelenberg
Dawie Kriel, director at Energy Partners, has also noticed the changes in refrigerants. “CO2, propane, and other natural refrigerants continue to gain ground,” he says. He also notes that R407f is becoming more popular as a medium-temperature alternative and that other new refrigerants are also being considered now.
Another trend that Robinson has noticed is that supermarkets are moving to smaller formats in terms of footprint. Refrigeration-wise, five years ago, a large installation would have about 70–80 points per store, whereas now it’s more in the 50–60 range. “The demand has changed; most people don’t seem to be shopping in hypermarkets anymore,” he explains. “It’s all about convenience now.”
Using waste heat from the refrigeration system has become standard as well now, according to Shaun Hadfield, operations director at Commercial Refrigeration Services (CRS). It can be used for domestic hot water as well as space heating. “When it comes to using it for space heating, it’s a no-brainer. The return on investment is very quick, especially on CO2.”
“There is a lot of work and R&D being done to fine-tune existing technology to make it more efficient,” says Hadfield.
Electronic control, monitoring, and diagnostics, with the ability to maintain equipment within design operating envelopes, is where technology is going, says Kriel. “This will give rise to the use of AI in optimising maintenance and plant performance improving the utilisation of scarce skills such as refrigeration technicians.”
“An energy-efficient and well-designed plant can pay for itself in the long term through savings.”
Energy savings is a huge focus — more so than ever. To optimise this, various technologies and products are gaining popularity, explains Kriel. These include:
- Modulating unloading heads on compressors to cater for variable loads
- Variable speed drives for capacity control of fans and compressors
- EC fans
- Electronic expansion valves
- Brushless DC compressors
- LED lights in cabinets and rooms
- Perspex and glass doors on chiller cabinets, creating large savings
- Raised suction temperatures and reduced condensing temperatures, sometimes using ‘floating’ algorithms in controls
- Detailed energy and temperature monitoring with trend logging and active management.
Refrigerants are also being pushed to be energy efficient and environmentally friendly.
Ejectors on CO2 systems are also a technology to watch, according to Hadfield. “The ejectors are great for high ambient temperatures,” explains Hadfield. “It’s vital for reducing power intake.”
Common design mistakes
A big challenge is the fact that retailers often direct most of their energy on the trading floor, mostly because that is the part of the store they believe generates the sales with their customers, explains Smith. This means plant rooms or suitable plant areas are often forgotten of and seemingly squeezed into some location that would not have been selected had consideration not been given to it from the get-go.
The client often gets convinced to accept a system that does not deliver under high stock volumes or high ambient temperatures. These systems will be cheaper, and all goes well until some hot or busy days arrive. All too often, the competitive nature of the industry means capital expenditure cost is placed over operational expenditure when deciding on which plant to install. “An energy-efficient and well-designed plant can pay for itself in the long term through savings,” explains Smith.
Kriel agrees that a big design mistake is not considering the total cost of ownership. “The total cost of ownership is 66% driven by energy cost.” Not considering the distinct characteristics of alternative refrigerants is another mistake.
Naidoo highlights the biggest design issue as engineers designing synthetic refrigerant systems instead of natural refrigerants, as it is perceived as cheaper. “They need to think more about the overall picture and move forward towards a more holistic approach that combines all systems and not only the refrigeration applications.”
Another problem is cutting corners to save costs. “Most of the jobs going out are cost-based and as such, sometimes this means that some engineers will skimp on products to bring down cost,” says Hadfield.
There is also a lack of technical information being passed from the older generation to the younger generation, says Hadfield.
Kuzma notes that some common errors include not catering for the increasing ambient conditions. “We are seeing companies using water-based systems in a water-scarce country.”
Natural refrigerant products for retail applications were widespread at the 2018 Chillventa show and manufacturers are spending a lot of R&D in this field.
Image credit: Ilana Koegelenberg
But it’s not just about the design; on-site work and maintenance can be problematic, too.
“General contracting standards are good; however, the shortage of skills does have an impact on quality of workmanship in preventing gas losses, for example,” says Kuzma.
Maintenance is vital. Sometimes people sell a store design that is highly efficient initially, explains Robinson. But then the different service companies/technicians change the system set-up/settings, changing things (often not making informed decisions). And soon the system is no longer running efficiently at all.
“Commissioning of the system is sometimes a problem, too,” says Robinson. A system often gets switched on without being properly commissioned. “Sometimes there simply isn’t any time for adequate commissioning in the construction programme. Proper commissioning takes a few days and needs to be done right.”
Kriel agrees that a big problem is not providing enough time to complete the process properly and allowing the delays of other trades to compress the commissioning period.
Another issue is not actually doing the system maintenance or not renewing service level agreements after the first year. Sometimes the client will get an in-house person to do the maintenance but who isn’t skilled or knowledgeable enough to do it properly, explains Robinson.
Considerations for system selection
So, which factors should be considered before designing a specific supermarket refrigeration system?
“Design should be based around minimising life-cycle costs and ‘future-proofing’ the system,” advises Kuzma. “Running costs must be minimised by incorporating all the latest energy-saving technologies and using a natural gas that is not subject to phase outs and shortages.”
It is important to ask these three questions, according to Hadfield:
- Who is your client?
- What is the size of the store?
- Where is the location of your installation?
Kriel agrees with these but adds that one should also consider the availability of service and repair contractors, as well as the availability of spares and refrigerant.
If the location is too remote, there won’t be the necessary resources to look after a sophisticated system. Especially for some installations in remote locations in Africa, it’s better to keep it basic and simple.
Other than these, Naidoo suggests considering local and international trends, as well as taking a holistic approach and not just focusing on the refrigeration systems alone.
Design the system so that regular maintenance and repairs can be done effectively and speedily, advises Smith. Also, take into account the required lifespan of the design. How long will the client expect this plant to last before they replace it? “Remember, some refrigerants will eventually have finite lifespans or cost a premium before their phase out.”
Outsourcing refrigeration plants, like this one at PnP Darras in Johannesburg, is becoming more popular, too.
Image credit: Ilana Koegelenberg
Standards and regulations
All the latest South African National Standards (SANS) must be adhered to and all technicians/designers working on these refrigeration systems must be registered and trained by the South African Qualification and Certification Committee for Gas (SAQCC Gas).
SANS 10147, ISO, and International Electrotechnical Commission (IEC) standards or equivalent are relevant. In addition, consider inputs from ASHRAE, the International Institute of Refrigeration (IIR), and other international publications for additional information, advises Kriel.
So, what does the future of supermarket refrigeration look like?
The future is definitely more sustainable. A lot of new technological advancements are geared towards optimising the cold chain, from farm to fork, explains Naidoo. “Not only does an energy-efficient cold chain reduce CO2 emissions, but it also helps to deliver on many of the UN’s Sustainable Development Goals.”
“Technology for energy-efficient cold chains, like cold storage rooms and energy-efficient refrigerated trucks, already exists,” explains Naidoo. “However, to make progress with sustainable cold chains, we need increased awareness on the topic and the right conditions within governments.”
“In my opinion, small compact natural gas solutions that are very energy efficient will be in demand,” predicts Kuzma. “Placing doors on refrigeration cases will also become the norm to further reduce energy consumption and enhance the cold chain.”
Even the local FRIGAIR show boasted a lot of new and exciting developments in terms of retail refrigeration and energy savings.
Image credit: Ilana Koegelenberg
Kriel sees a combination of the technologies currently available, with an increase in low global warming potential (GWP) refrigerants and better efficiencies in future. He also predicts that it will become easier to interface with the equipment and diagnostics of the plant. As well as increased remote supervision of the store and plant on a continuous basis. “In future, we’ll also see more outsourced cooling where plant ownership, design, procurement, and maintenance is provided by specialists and the client pays only for the refrigeration cooling used as a utility,” he says.
“I think supermarket refrigeration is difficult to predict because new technologies are being discovered, invented, and older ideas are being reinvented as well,” says Smith. “I think we can expect that the expectations of refrigeration systems will become more and more competitive.”
The cost of refrigeration is an extremely competitive market, especially in the supermarket environment.
“The need for energy efficiency and performance will be driven to higher expectations from equipment, and surrounding it all will be the drive to make systems more environmentally friendly with low carbon footprints,” concludes Smith.
Read the full article with extra inputs in the upcoming March/April edition of Cold Link Africa.