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You need to know
-
The floor area
of the room
-
The size and
position of windows, and whether they have blinds or shades
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The number of
room occupants (if any)
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The heat
generated by equipment
-
The heat
generated by lighting
Floor Area of
Room
The amount of
cooling required depends on the area of the room. To calculate the area
in square metres:
Room
Area BTU = Length (m) x Width (m) x 337
Window Size and
Position
If, your room has
no windows, you can ignore this part of the calculation. If, however
there are windows you need to take the size and orientation into
account.
South Window BTU =
South Facing window Length (m) x Width (m) x 870
North Window BTU =
North Facing windows Length (m) x Width (m) x 165
If there are no
blinds on the windows multiply the result(s) by 1.5.
Add together all
the BTUs for the windows.
Windows
BTU = South Window(s) BTU + North Window(s) BTU
Occupants
You will have to
take that into account people who normally working in the space. The
heat output is around 400 BTU per person.
Total
Occupant BTU = Number of occupants x 400
Equipment
Clearly most heat
in a room is generated by the equipment. This is trickier to calculate
that you might think. The wattage on equipment is the maximum power
consumption rating, the actual power consumed may be less. However it is
probably safer to overestimate the wattage than underestimate it.
Equipment
BTU = Total wattage for all equipment x 3.5
Lighting
Take the total
wattage of the lighting and multiply by 4.25.
Lighting
BTU = Total wattage for all lighting x 4.25
Total
Cooling Required
Add all the
BTUs together.
Total
Heat Load = Room Area BTU + Windows BTU + Total Occupant BTU + Equipment
BTU + Lighting BTU
This is the amount
of cooling required so you need one or more air conditioning units to
handle that amount of heat.
Disclaimer:
These calculations are intended as rough guide only. Complete accuracy
cannot be guaranteed
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