Category: Design
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
Cooling load is the total heat entering a space from sun, walls, roof, glazing, people, lighting, equipment and outside air. It is measured in tons of refrigeration or BTU per hour; one ton equals 12,000 BTU/h.
Why it matters on a project
It sizes the units, the ductwork and the electrical load. Guessing it gives rooms that will not cool in August, or oversized units that waste power.
Worked example
A 4 × 5 m room = 20 m² at a rough 18 m² per ton: 20 ÷ 18 = 1.1 tons, about an 18,000 BTU/h unit. The final figure comes from a load calculation, not this rule.
Common mistake
Picking a room unit by floor area alone, ignoring a west facade or an uninsulated top-floor roof.
Frequently asked questions
Is the square metres per ton rule enough?
Only for a first estimate; it varies a lot with a west facade, top-floor roof and glazing ratio.
Who calculates the cooling load?
The mechanical engineer, with load calculation software, as part of the MEP drawings.
Related terms
- MEP drawingsElectrical, plumbing, HVAC and fire drawings.
- Thermal insulationMaterials reducing heat transfer through walls and roofs, required by the Saudi Building Code.
- Double glazingTwo glass panes with an air or gas gap to insulate heat and sound.
- Electrical load scheduleA table summing each board's loads to size breakers, cables and the meter.
Read next
Does your project need architectural design and construction drawings? Send the drawings or a short description and we reply within one working day.
Service detailsRequest a quote