Saying that the quality and efficiency of a cold store depends on the quality of the main components that make it up, Ghaleb Abusaa provides a step-by-step guide.

Construction outlines

There are several features that go to make a model cold store. But if one were to reduce them to a basic list before undertaking its construction, the following items would be top priorities:

• The weighing station
• The trailers, medium and small trucks parking area
• The docks’ arrangements and quantity
• The steel structure
• The civil works and floor area
• The service corridors behind/around the cold rooms/store peripheral
• The insulated envelope
• The rooms’ height
• The number of rooms and their storage capacities

Let me discuss the items on the list one by one.

The weighing station

The purpose of the weighing station is to monitor the incoming and outgoing loads entering the cold store through proper electronic weighing scales connected to a centralised monitoring and control system. This controls many aspects, such as possible theft and the percentage of defective and reject items out of the total periodic incoming and outgoing quantities. This helps keep a tab on everything, and judge the quality of the storage and refrigeration systems.

The trailers, medium and small trucks parking area

The size and layout of traffic in this part of the cold store govern the productivity and handling of the products in both time and quality of the products. Therefore, their importance cannot be emphasised enough. When there is a long waiting time, the natural human tendency is to switch off the trucks’ refrigeration systems to save money. This could prove detrimental as it might result in reducing the quality of food and/or in spoilage of the products. Thus, proper design of this area is vital for a proper cold store output.

The docks’ arrangements and quantity

The following list can serve as a ready reckoner with regard to the docks:

1. The dock levellers
2. The dock shelters
3. The guides, the sump pit and submersible pump plus other accessories in the vehicles parking area
4. The number of docks to match the approximate maximum daily intake/discharge plus extra for emergency purposes and possible future expansion
5. Medium and small vehicles may enter the handling area via a ramp rather than having a special dock for them
6. Docks’ doors – quick lift sectional insulated doors are recommended instead of rollup doors

The steel structure

There are three things that need to be given due consideration with regard to the steel structure:

1. One needs to make sure that the steel structure is designed to carry the extra loads of the insulated roof and coolers, especially with a wide span. Therefore, some thought and planning needs to be invested in this.
2. Extra steel bars/angles and the like need to be added to the roof structure (main beams and/or Z berlins) to hang the insulated panels via insulated threaded rods. It needs to be noted here that the steel structure manufacturers normally do not allow welding for expansion and contraction purposes. They rather use a bolting system.
3. If need arises and some columns fall within a cold room, the columns need to be insulated to prevent heat bridges and condensation.

The civil works and floor area

For holding freezers to store frozen products usually at -20°C or lower, electric heat mats or other means, such as ventilated floors are required when the floors are on the ground level. This is in order to prevent frosting and possible failure of the entire structure if frost accumulates under the floor. Floor insulation and final reinforced concrete slab need to be cast on top of it.

The service corridors behind/around the cold rooms/store peripheral

To be able to install the insulated envelope wall panels and for future service of the cold store, we need to factor in a service corridor. One can assume that a maximum of one- metre-wide service walkway behind the peripheral of the cold rooms would be required.

The insulated envelope

For a typical cold store, it is safe to expect the following ranges of space temperatures as per industry standards:

1. All holding freezers are normally designed at -20°C. (The process of freezing is not applicable.) The frozen goods are normally received at a maximum of -10°C and the rooms will drop the temperature of the goods down to -20°C.
2. All chilling rooms are normally designed to a minimum of zero degrees Celsius. However, the room temperature can be adjusted above zero, as applicable to the particular product being stored. To calculate the cooling capacity required for such rooms, we need to know at what temperature such goods are received. Fresh fruits and vegetables normally enter the room at ambient temperature, unless pre-cooled.
3. Dry/canned food is normally stored at air conditioned room temperature, say around 20°C. Some are designed for 15-20°C.
4. Area for handling, receiving, inspection, packing, packaging, grading etc is normally maintained at air conditioned room temperature level (Same as c above).
5. The floor insulation is normally made of high-density extruded polystyrene capable of standing the force applied on it, density ranges between 35 and 40 kg/Mt3.

It needs to be noted that the thickness of the insulated panel will be decided based on the room’s final temperature. Normally, it is 50 mm for items c and d above, 100 mm for item b. and 150mm for item a.

The rooms’ height

A thumb rule that needs to be remembered here is, the higher a room’s clear height, the better the utilisation of the floor space will be (going vertical). However, handling such storage at high levels needs special arrangement. The traditional stacking using forklifts does not seem practical for heights over six metres. Heights in excess of that require narrow isle forklifts. But this will require fixed racking and small weight and volume packaging.

The number of rooms and their storage capacities

How many rooms a cold storage needs to have is a hard thing to decide without knowing many other factors, such as the variety of products and types to be stored, for example, if it is for one’s own business or if it is built to lease to others, the cycles per year, etc.

However, we have more than one option, as follows:

1. Install commercial-type refrigeration system, standalone, each room has its own equipment
2. Centralised industrial-type system for the full cold store
3. In both cases (a and b), we may have a single application for each room (either above or below zero) or multi-use rooms where any room can be used for above and below zero application. Though this is a costly solution, it has wide diversity and flexibility in operation. Each of the above options has advantages and disadvantages that are normally explained to the client to help them decide which way to go.

In a nutshell, keeping in mind the above as the basic outline will help construct a good quality cold store, which takes into account the present and future needs and ensures that the quality of food entering and exiting is not compromised.

The writer is CEO of The Three Factors Company (en3 Solutions). He can be contacted at g.abusaa@en3solutions. com