Cooling Load Calculator

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Introduction to our cooling calculator

A room air conditioning load is made up of heat flowing into the room through the following components:

  • Transmission load – Sensible heat gain through walls, floors and ceiling
  • Solar load – Sensible heat gain through transparent building fabric elements (windows, doors)
  • Internal loads – Heat gains from lights, appliances, equipment, activities and people
  • Infiltration air load – Heat gain from air infiltrating from outside and adjoining spaces through doors and other openings
  • Ventilation air load – Heat gain from minimum outdoor ventilation air provided in occupied spaces.

All of these separate loads are then added together to get the full cooling load on the air conditioner for that room.

Simplifications for residential applications include ignoring load diversity and simplifying calculation of latent cooling loads.

To use the FairAir Cooling Load estimator you will need to know:

  1. The region (climate area) that the room is located in
  2. The dimensions of the room to be air conditioned: length (m), width (m), height (m)
  3. The total area (m2) of ceiling, floor, external walls, external glazing (windows and doors) and internal walls (separating walls/doors) to other rooms or areas that are not included in the air conditioned room.
  4. The type of construction of the main building elements: roof/ceiling, floor, internal and external walls, including whether they have been insulated or not
  5. The type of any glazed windows and doors, and the orientation of the glazed areas (the compass direction they face), and the extent of any shading that applies to the glass, such as permanent overhangs and awnings or internal blinds and curtains
  6. The number of occupants in the room and the type of room usage, either living room or bedroom.

Based on the user input and the in-built default assumptions, the FairAir Cooling Load estimator will provide an estimate of the cooling load for that room.

Find out more about Reducing the Cooling Load of a Room.

Find out more about Energy Efficiency, Installation and Maintenance.


The FairAir Cooling Load estimator is an estimate only, based on a series of assumed default values and a series of user inputs. AIRAH recommends a full load calculation be completed by an air conditioning contractor or designer. Individuals with load estimation experience are best placed to provide the most accurate cooling load estimate, appropriate to the actual cooling (and heating) loads and the occupant needs.