Air conditioners for shops and offices: tonnage and star ratings

Cooling a shop, showroom or office is very different from cooling a bedroom. Doors open constantly, lights and computers add heat, and many people share the space. An AC that is too small runs flat out and still cannot keep up; one that is too big wastes money. Getting the size and type right is where the savings are.

Size for heat load, not just floor area

Tonnage depends on more than square feet:

• Room size and ceiling height
• Sun exposure and glass frontage
• Number of people at peak times
• Lights, computers, kitchen equipment and machines
• How often doors open

Ask the supplier or HVAC contractor to do a heat load calculation or site survey rather than using a rule of thumb.

Choosing the type

• Split ACs — common for cabins and small offices.
• Cassette ACs — fit in the false ceiling and spread air in all directions; popular in shops and open offices.
• Ductable units — hide the equipment and deliver air through ducts to several points; suit larger spaces.
• VRF/VRV systems — serve many rooms from central outdoor units; used in larger offices and buildings.

Inverter technology and energy ratings

• Inverter ACs adjust compressor speed and usually save power in spaces with varying load.
• Energy ratings (star labels) help compare efficiency. For long daily running hours in commercial use, efficiency matters a lot over the years.

Installation quality

Poor installation undoes a good AC.

1. Ask what is included — copper piping length, stand, drain pipe, electrical work.
2. Check the outdoor unit location has ventilation and is allowed by the building.
3. Ask for proper insulation of pipes and a stable electrical supply, with a stabiliser if needed.

Service and warranty

• Ask about warranty on the unit and compressor.
• Ask about annual maintenance contracts — filter cleaning and servicing before summer keep efficiency up.
• Check how quickly service engineers respond in your area.

Mistakes to avoid

• Sizing by a rule of thumb. A shop with glass frontage and constant footfall needs far more cooling than a closed cabin of the same size. Insist on a site survey.
• Putting the outdoor unit where it cannot breathe. An outdoor unit squeezed into a closed duct or facing another unit's hot air works harder and fails sooner.
• Skipping the stabiliser or electrical check. Voltage swings damage compressors. Ask whether your supply needs protection and whether the wiring can take the load.
• No pre-summer service. Clogged filters and coils quietly raise power bills. Book servicing before the peak season, when technicians are easier to get.

What to include in your enquiry

• Area, ceiling height and type of space
• Number of people, equipment and glass frontage
• AC type preference, or ask for a recommendation
• Installation requirements and building constraints
• Your location and required date

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