In order to choose the exact power required for our air conditioner, we must take into account not only the surface area and height of the room, but also various factors: exposure, thermal insulation, whether the room has heat sources such as a hob, oven or other.
We can quickly and reliably multiply the metric cubic metres by 35 W/m3 to obtain the power requirement in watts.
Example:
25 m2 ( surface ) X 2.70 m ( height ) = 67.5 m3
67.5 m3 X 35 W/m3 = 2362.50 watts
1 W corresponds to 3.41 BTU/h
Therefore 2362.50 watts X 3.41 = 8056.12 BTUs (a 9000 BTU is the ideal size).