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  • Monday December 28, 2020
  • By Electro-Ref Tech

How To Calculate The Air Conditioner Capacity (Ton) For Our House ?

How To Calculate The Air Conditioner Capacity / Size (Ton) For Our House ?

Ton of Refrigeration (TR) : A Ton, as used in the HVAC field, is a term that describes how much heat the AC unit can remove from a home in one hour. One Ton of Refrigeration (TR) equals to 12000 btu/hr or 3.516 Kw or 3023.95 kcal/hr.

These four things have the biggest impact on what size air conditioning unit you’ll need:

  1. Room size: what’s the length, width and ceiling height? While floor space is important, so is total volume – a room with high ceilings will require more energy to cool.
  2. Insulation: are the ceilings and walls insulated? What’s underneath and on top of the room? Ceiling insulation is one of the biggest factors in making your home thermally efficient.
  3. Location: where do you live? A room in Darwin will need a more powerful air conditioner for cooling, compared to an otherwise identical room in Hobart.
  4. Orientation: which way does the room face? A large north- or west-facing window can let in a lot of heat in summer, whereas a shaded, southern-facing window will be cooler.
  5. Heat producer: Includes number of people, electric light, computer or machines which produce heat in room causes adds heat in that room so we must mention in our calculation.

To choose what size air conditioner is for right for you, you need to first calculate size of the home spaces served by the air conditioner, in square feet.

In Kathmandu (Nepal) region’s house having with brick wall and 9 to 10 feet height of room at that case we can simply calculate required size of AC by this formula

TR = L × B × 80  ÷ 12000


L= Length of room in Feet

B= Breadth of Room in Feet

For example:

Length of Bed Room = 10 Feet

Breadth of Bed Room = 15 Feet

Hight of Bed Room = 9 Feet

There for required size of AC in this room is,

10  × 15 × 80 ÷ 12000 = 1 TR

1Ton = 12000 btu/hr or, 3516.85 W or, 3023.95 kcal/h.


This formula is only applicable in where temperature is between 5 to 40 degree Celsius like Kathmandu region of Nepal. For auditorium room where Hight of room is very high and also there may be maximum number of people and lights which produce heat in that case this formula dose not applicable. Its mean for commercial purpose you must need to consult with HVAC engineers to calculate proper heat load.

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