A number of environmental factors are known to affect large-scale insulation strategies. So, how does wrong insulation affect coolrooms and freezers? There’s that single glaring consideration, the image of lost energy due to thermal leakage. The wrong type of panel has been installed, and it’s either too thin or built from substandard materials that aren’t designed to maintain the climate set by a cooling thermostat. This lack of protection causes a subsequent rise in your electrical bill to offset the losses, leading to an inefficient setup. An energy audit will illustrate this activity along an axis of time, showing transient spikes of lost energy and the resultant costs incurred by this feeble configuration. Thicker insulation panels made from modern composites are adept at resolving this undesirable scenario, especially injected polystyrene, foam polyurethane, and other composites that blend space-age plastic and glass.
The above example is the initial consideration all businesses question when a coolroom or freezer is first installed, simply because all commercial facilities are profit-oriented as they should be. In other words, a business doesn’t want to see profits floating through an aluminium wall in the form of lost energy. While a valid point, there are other cases in which the type of insulation can cost a business hard-earned cash. For example, do opt for a space-age cyanurate foam with 3 inches of thermal protection, but think twice about installing a comparable fibreglass solution because fibreglass draws moisture and can easily become the home for a colony of mould. Since freezers are full of frozen water, this panel configuration could be a recipe for disaster. Again, it’s the duty of the cooling engineer to account for this scenario, a practice that involves the assessment of ‘dew point’ properties and the ‘R-value of the chosen insulator.
Use hydrophobic materials to avoid mould and mildew during a defrost cycle. Waterlogged insulation is unhygienic and apt to bloat and sag, thus damaging the finely sealed joints that keep the freezer chamber enclosed. Thankfully, insulation science has evolved fast due to advances in thermal isolation technology. Modern laminated panels now incorporate injected or extruded plastics that deliver high R values, which, for those not indoctrinated in the ways of cooling technology, shows the resistance of a material to heat loss. Superior to fibreglass insulation in every way, modern plastics don’t absorb water. Fibreglass, on the other hand, can soak up moisture, which leads to the formation of bacteria.
In not addressing insulating issues with due diligence, business owners run the risk of selecting a material that’s unsuitable for the required application. If the inner environment is moist, avoid fibreglass and other non-hydrophobic substitutes. This simple act will eliminate the possibility of mildew. Also, consider the overall mechanical strength of the chosen insulating panel. A metal backing has its own role to play, that of providing a corrosion-free exterior and rigid reinforcement characteristics that bolster the overall structure of the coolroom or freezer. Always talk to your cooling professional and match the insulation to the contents of the room and the required cooling temperature.
Temperature is a considerable factor when selecting a coolroom or freezer. While a coolroom is intended to keep its contents cool (like a home fridge), a freezer must actually freeze the contents and maintain a temperature below zero.
Coolrooms and freezers must be constructed in accordance with Health Department standards. Freezers require more wall insulation and different floor construction than coolrooms. High thermal and insulation panels control temperature and humidity. Sandwich-type panels made of continuous lamination that bonds sturdy aluminium or colorbond to both sides of a polystyrene core is a preferred construciton. This type of panel is strong, durable, and provides long-lasting hygienic storage, operation, and resistance to mold and bacteria. It also alleviates future need for time-consuming protective painting. Vermin control, coving, and industry-specific silicone sealants standards must also be met.
There are State and federal government incentive programs available to help cover some of the costs of upgrading or replacing facilities to more energy-efficient versions.
Coolroom Design/Selection
Realistically determine the refrigerated space the business actually needs. Poorly designed systems tend to have the lowest capital costs, highest operating costs, and shortest useful life.
Oversized rooms or equipment consume more initial capital- and ongoing energy-costs. Oversized compressor motors and undersized evaporators/condensers (heat rejection) consume more energy and capital.
Also consider added design features that increase the initial cost, running cost savings over the expected life of the room / system, the environmental warming impact (TEWI), and the life-cycle cost (LCC). Also pay close attention to part-load energy performance.
Refrigerant options such as R134a that use less power and higher GWP than most other HFCs and traditional synthetic refrigerants recoup their higher initial cost in the first few years. Benefits of using natural refrigerant alternatives, such as carbon dioxide, ammonia, and hydrocarbons are: good overall energy efficiency, zero ozone depletion potential (ODP), low global warming potential (GWP), and environmentally-friendly and levy-free status.
Secondary refrigerants may reduce primary refrigerant charges and pumping power while improving humidity control.
Additional coolroom and freezer Best-Practice options targeting temperature control include:
• thicker insulation and fast-closing automatic doors,
• highly efficient refrigeration plant with variable-speed compressors and fans,
• reduced temperature differences across heat exchangers,
• reduced compression ratios, dual-stage compression,
• low-energy LED lighting,
• leak-tight pipe installation, and
• desuperheaters, and modern control and defrost strategies.
Managing and Reducing Thermal Loss
Air-tight insulation eliminates infiltration of warm moist outdoor air. Vapor barriers reduce refrigeration loads. Refrigerated product adds thermal mass to minimize system runtime and cycling.
• Optimize the storage capacity (66% for coolrooms; 75% for freezers);
• Install a variable-speed compressor (do not block evaporator airflow;
• Regularly calibrate thermometer/thermostat/controller and gauges;
• Check automatic electric defrost timer settings;
• Install a power meter;
• Upgrade controls with direct digital control (DDC) panels.
Reflective and thermal coatings, compact fluorescents/LED lighting systems reduce energy consumption and internal heat loads.
Maintenance and Replacement
Repair leaks, monitor refrigerant levels, and be suspicious of refrigerant top-ups. Intentional (poorly maintained systems) refrigerant emission is illegal.
Energy-efficient interventions should only be performed by qualified engineers (M.AIRAH) and licensed technicians.
Where CFC (R12) and HCFC (R22, R502) based systems are old or rundown, replacement with a modern energy-efficient solution is usually the best long-term option.
C&M Coolrooms can create a custom solution for your specific needs. Talk to one of team members today.
