By Eamonn Ryan
Insulated panel systems are ideally suited for thermally controlled environments such as cold storage freezers, coolers, food processing and packing facilities.
Critical to today’s cold chain is the energy saving achieved by insulation around refrigerated spaces, and more specifically insulated panels. The more that lower temperatures can be conserved, the less the refrigeration plant has to work.
Insulated panels are associated for the most part with storage rooms for produce. However, their application in the cold chain extends further into cold and freezer rooms, food production facilities, display fridges, food preparation areas, abattoirs, medical rooms, growing environments, specialist applications, distribution and transportation services – any area where conditions for control are required in order to avoid premature decay of the product. This may include temperature as well as hygiene safety factors, and are also critical to fire retardation.
South Africa has, over the last few years, seen the construction of countless facilities as the country becomes increasingly reliant on imports – particularly cold stores and distribution centres directly related to the cold chain. Local and international organisations and manufacturers alike have achieved the raising of standards.
Supermarket cabinet retrofits accelerate
Retail supermarkets are closely concerned with their daily electricity consumption, given how much many are paying on diesel to prolong the life of foodstuff in their refrigerated cabinets, open displays and top sliders. Closing open displays in supermarkets by putting glass doors on the front or top to contain energy for longer can result in savings of up to 40% of the energy consumed by their cabinets, which is one of their major expenses. This means their refrigeration plant is not going to have to work for as long as it previously did to get the same temperatures in their cabinets, as they’re no longer open.
At least one supplier reports a big jump in interest in retrofits this year compared to last, due primarily to Eskom’s loadshedding. Funds are being made available for retrofits on a large scale by some supermarket franchises to look at energy saving alternatives.
Retrofits to pull back the kilowatts required have been one of the key themes in the sector among those businesses able to undertake such retrofits. The sliding door has to be tailored to a specific cabinet, and the refrigeration temperature has to be throttled back or products will freeze – as it isn’t pulling in the same amount of ambient air. Consequently, ‘first prize’ would be for the initial design to incorporate the glass doors.
This doesn’t apply everywhere: in high traffic discount supermarkets the doors are being continually opened letting in the ambient air, and doors also get damaged due to narrow aisles.
The major focus at the moment for anyone in the HVAC&R sector is how to assist customers to save energy.
For instance, there is a shift to thicker insulation panels for certain applications, though whether a project owner opts for this often comes down to the financial viability comparing whether the higher price of the thicker panel is worth the long-term saving of electricity or condensing unit time. When 80mm would suffice why spend extra for 100mm?
An anchor tenant in a particular building is not the one making the decision – typically a retail franchisee is on a three-to-five-year lease and wants only something functional. It’s the mall owner’s decision as it is they who are primarily interested in keeping down their cost, while a contractor is equally concerned as to a supplier’s quality and service delivery.
Mall owners may be prepared to look at capex from a total cost of ownership perspective in terms of lowering ongoing maintenance and energy costs down the line, though elsewhere historically the trend has been primarily to look at only the upfront capex. Now the current electricity outages debacle has forced developers to take a closer look at anything related to reducing energy consumption, and insulation falls squarely into that concept.
In comparing polyurethane with polystyrene, the choice boils down to the density value (DV) in the polyurethane panel. While polystyrene is cheaper, there are variances in grade.
Some products have had a reputation for being a fire hazard, and some manufacturers have responded with a fire-retardant product – but not all. Polyurethane has always been known as more expensive but is known for its fire self-extinguishing property.
R&D at various manufacturers involves a look both at other insulation types as well as the energy efficiency of existing products such as a polyisocyanurate (PIR) panel, which is safer and more eco-friendly. The flame retardant in polyiso is less toxic than the types used for other insulations. The drawback is that this is the most expensive of all the options.
Insurers are becoming more aware of the need for better fire-rated panels in structures to reduce their risk. In response, some panel manufacturers are embarking on an education drive among customers on the benefits of fire retardation and the financial benefits flowing from reduced insurance premiums as well as its lower risk.
Increasingly the cooling aspect of insulation panels will have to work hand in hand with its fire-retardant qualities, and this varies depending on the particular application, for instance whether a residential structure or for storage.
Different options and applications
Tammy Grove, manager of Kingspan South Africa explains the different options, applications and thermal properties. “The options are various, and widely available: Thermoset insulated materials such as polyisocyanurate (PIR) Quadcore or Polyurethane, or Thermoplastic insulated materials such as Polystyrene. Each has their specific use in the market.”
For the different thermal properties, she suggests contractors request from the manufacturer the U-value to ensure when you are comparing sandwich panels that you are comparing ‘apples with apples’. Each insulation offers different properties, some performing for one year while others could be warranted to approximately 20 years, she cautions.
For factors that should be considered when using panels, piping, roofing, refrigerated vehicles and elsewhere: “The use of sandwich panel insulation is widely used in various applications to assist with making the building envelope more efficient. Typical uses are in controlled environments, which have either the requirements for temperature control, for example, freezer facilities, as well as dust control in data centres or hygiene control in other sectors such as pharmaceutical. Facades and roof insulated panels are also specified in the market as commercial facilities need to perform efficiently.
When it comes to reducing heat, she notes: “The insulation of choice has an impact on the efficiency of heat control. The U-value and stability of the thermal performance of a sandwich panel play a huge roll in selecting what insulted panel to use.”
In respect of vapour barriers of stainless steel or glass fibre, each with its own properties and costing, and the like, Grove recommends one follow the manufacturer’s shop drawings for installation guidance as many of the components are used for vapour barriers, while the lifespan of insulation once in service “all depends on which technology and which manufacturer you align with”.
“With thermal monitoring systems, most failures happen at the cut edge of a panel as you are required to infill with foams to fill the gap and that is a human influence which implies it could be installed correctly or not,” says Grove.
New insulation product soon to be on market
Entrepreneurs Satish Mudaliar and Carl Supra have developed a new form of precast concrete panel which they claim provides a high degree of insulation, because of the 80mm void inside the 100mm concrete panel.
It provides insulation not only from heat but sound, says Supra. Their R&D development of the panel commenced with polystyrene and polyurethane, they explain, but they found their current technology beats those options on price.
“Our product sets new standards because of the 80% void – and a void costs nothing. To manufacture it requires a steel frame and the concrete is poured around the plastic void. It’s suited to mass manufacture which keeps costs down. It is as solid as concrete and easier to transport,” says Mudaliar.
It is suited to applications such as internal walls, affordable housing, schools and also has applicability in supermarkets. The product is in the developmental stage with the final test still to be completed.
Supra says polystyrene concrete has been around for some time and is an excellent medium for construction, but extremely cumbersome to work with on site. “With our mass manufacturing, we can send a structure in a box on the back of a truck – it is that light, but still strong. On site, there is a steel structure that the panels fit into wherever you are in the world, where it can be cemented in.
“We’ve created a panel which has voids in it which displaces 80% of the concrete but with the same strength. Each side of the panel is 10mm thick, and it is poured in such a way that the concrete flows across and joins up with the other side to make a composite structure. We place a woven polypropylene cloth designed in such a way that it’s feathered in order to adhere to the concrete and embeds into the two sides, with additives to make it flexible. This can then be moulded 2.4m high and 600mm wide, for instance. They can be taken to site on a bakkie and placed in the structure by two workers. With ordinary concrete panels, it would require a crane to move them.”
Mudaliar adds: “Cement is one of the biggest contributors to carbon emissions on the planet, and this application reduces the concrete volume by 80%.”
Factors to consider when choosing insulated panels
By Lizelle van der Berg, director – GCCA South Africa
An insulated panel system can be applied to atmospheric-controlled environments where finished product protection and hygienic control is of greatest importance. In South Africa, there is a wide variety of panels available in polystyrene (EPS), polyurethane (PUR), polyisocyanurate (PIR), phenolic, rockwool and mineral fibre. The question is: ‘What do you need to consider when choosing insulated panels for your facility?’
Tammy Grove, manager of Kingspan South Africa explains that the factors that determine insulation choice are durability, cost, fire performance, thermal performance and vapor tightness. “Choosing third party insurer approved panels that have low U-values, backed with long term manufacturer warranty on structural and thermal performance would provide peace of mind for the cold store investor for a safe, high performance and long-lasting cold store,” says Grove.
Energy efficiency
Christo van der Merwe, of MRE Marine and Refrigeration Engineering, explains that insulated panels reduce the amount of heat that enters a freezer store through the walls and ceiling, provides a vapour barrier to reduce the moisture that enters the cold space and provides a secure, hygienic enclosure for the containment of product.
These functions are critical to the effective operation of a cold store – which is to achieve a desired room temperature while operating with a reasonable power consumption. Heat load from the walls and roof is the heat load that is affected by insulated panels. If the insulated panel wall thickness is increased, then the amount of heat entering the store will be reduced. The power consumption is directly proportional to the amount of heat that enters the cold store and must be removed to maintain the low temperature. If the amount of heat that enters the store is reduced, then the power consumption will reduce accordingly.
MRE considered two different cold store sizes, using 200mm Polystyrene panels to quantify the effect of increasing the thickness of the panels. It was noted that:
- The heat load from the walls and roof was a similar percentage for small and large cold stores at 25% vs 20%.
- The saving in heat load to increase the panels to 250mm was similar at 7% vs 6%.
- The saving in total heat load is similar as a percentage for the larger store but the more efficient ammonia plant results in a longer payback period.
- The saving in running costs justifies the additional capital expenditure for increasing the insulated panel thickness.
Grove explained that cold store operators should pay attention to the U-value of the panels to determine their thermal performance and that core types achieving low U-values with the lowest thickness will provide the maximum storage space for cold stores. “With the technological advancements in panel composition, one can obtain a greater thermal result from a thinner offering – thus, a higher R-value per mm of panelling,” says Avron Karan from Karan Beef. R-value refers to a material’s ability to resist heat transfer at a certain thickness.
When looking for a material to insulate your building you would generally look for a material with a high R-value, and therefore, one that can resist heat transfer well. U-value assesses the rate of heat loss through a given thickness of a building element (roof, wall, or floor). Ideally you would want a material which gains a small amount of heat in any given time, so you would want the U-value of a material to be low.
Insurance and fire
Danie van Zyl, divisional manager: corporate practice at Marsh explained that buildings with polystyrene sandwich panels have been featured in several severe high value fire losses over recent years. The fires, which often occur in the food industry, have had a marked effect on how the fire risk posed by polystyrene panels is viewed by insurers.
This is exacerbated by the fact that many firefighters believe that the risk to personal safety posed by a fire in this construction means that internal firefighting should not be attempted. Van Zyl further explains that there has been increased interest in alternative panel materials in recent years.
The fire performance of these varies from those panels which are largely non-combustible (such as mineral fibre) through to combustible panels. Non-combustible sandwich panels utilise core materials such as mineral foams, fibres and aggregates but still contain a small quantity of combustible adhesives. Maintaining panel integrity and preventing premature panel failure is important.
For new construction, van Zyl suggests the following:
- Providing ‘fire breaks’ by replacing sections of combustible panel with non-combustible panel.
- Consider the use of non-combustible or less combustible alternative panel materials.
- Sprinkler Installation and Fire Prevention Planning must be driven by the requirements in the Rational Fire Design (RFD).
- The RFD is based on a ASIB or SANS standard and will include sprinklers in the high-risk areas but will help to avoid costly sprinkler installations by compartmentalisation where possible.
If you plan to be in the industry for a long time and your budget is truly limited, Karan agrees that you should at least build intermediate fire walls in between rooms. Jaco Ollewagen, technical manager of CCS Logistics says, “Using a panel that has the proper fire rating is 1st choice but can be expensive. Alternatives can include installing non-combustible panels at strategic locations to serve as fire breaks while using fire rated boards installed behind Electrical DBs to further reduce the risk and one could also make use of IBR sheets to improve the fire rating around the building.”
Grove points out that stringent insurance industry requirements have led to the development of specific insurer-driven large-scale fire tests, to assess the reaction to fire performance of insulated panels with different cores. “FM Approvals is one of the most renowned insurance and risk management enterprises providing testing and certification services for property loss prevention products and services used in commercial and industrial facilities. FM Approved panels are subjected to a significantly more rigorous test regime and their mark is recognised and respected worldwide,” says Grove.
Another important factor to consider when it comes to fire is the amount of smoke released from panels when they are exposed to fire. You would want the lowest smoke release rating, meaning that if insulation is exposed to flames, the toxicity will not be harmful to your employees, the surrounding community, nor the environment. Grove highly recommends selecting FM Approved insulated panels to minimise damage to your property from any fire risk in the future. In case of fire, the right panel can prevent substantial property damage, as well as ensure that employees are able to escape without the panel walls losing integrity and their exposure to harmful smoke emissions is reduced.
When meeting with Karan, it was evident that risk mitigation was a cornerstone to their decision-making process. They took the approach of passive fire protection over the more common active fire protection, often seen throughout the South African landscape. Their rationale was that active fire protection such as a sprinkler system would still lead to a long period of inactivity in the event of a fire. Rather they looked at reducing the likelihood of a fire spreading in the first place, which they believed would leave less down time if a fire were to break out. Thus, more focus was placed on the components utilised to construct the facility.
Their reasoning for a Rational Fire Design was to try to produce a final product which collaborated with their risk mitigation ethos. Each environment is different, each may lend itself more to certain materials than others. One has to do their research prior going to market to find a suitable product and more importantly a suitable supplier of this product with the necessary inhouse skills and the backing to stand behind their offering.
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