How to Calculate BTU Per Square Foot
Measure your square footage., Determine the necessary heating or cooling capacity.
Step-by-Step Guide
-
Step 1: Measure your square footage.
Measure the square footage of each room you plan to heat or cool and add them together.
If you're installing a furnace or central air conditioning system, this typically includes every room.
In some homes, the ducts do not connect to the attic or basement.
For a rectangular room, multiply the length and width, measured in feet.
For a triangular room, multiply the length and width, then divide by two.
For a circular room, measure the radius r (the distance from the center to the edge).
Calculate πr2, or (3.14)r2 if you do not have a calculator with a π function.
For rooms with odd shapes, divide them into smaller pieces and measure each piece separately. , The capacity of furnaces and air conditioners is given in BTUs per hour.
You need to establish the correct number of BTUs per square foot for your house needed to either heat or cool it.
The methods differ for heating and cooling and are described below.
Many furnaces and air conditioners will be labeled "BTU," but this is actually shorthand for "BTU per hour" (BTU/h).
At a bare minimum, you can use a figure of 20 BTUs per hour per square foot and multiply this by the total square footage to be heated or cooled, but this does not take into account climate, the amount of insulation you have, or the way you live. -
Step 2: Determine the necessary heating or cooling capacity.
Detailed Guide
Measure the square footage of each room you plan to heat or cool and add them together.
If you're installing a furnace or central air conditioning system, this typically includes every room.
In some homes, the ducts do not connect to the attic or basement.
For a rectangular room, multiply the length and width, measured in feet.
For a triangular room, multiply the length and width, then divide by two.
For a circular room, measure the radius r (the distance from the center to the edge).
Calculate πr2, or (3.14)r2 if you do not have a calculator with a π function.
For rooms with odd shapes, divide them into smaller pieces and measure each piece separately. , The capacity of furnaces and air conditioners is given in BTUs per hour.
You need to establish the correct number of BTUs per square foot for your house needed to either heat or cool it.
The methods differ for heating and cooling and are described below.
Many furnaces and air conditioners will be labeled "BTU," but this is actually shorthand for "BTU per hour" (BTU/h).
At a bare minimum, you can use a figure of 20 BTUs per hour per square foot and multiply this by the total square footage to be heated or cooled, but this does not take into account climate, the amount of insulation you have, or the way you live.
About the Author
Richard Gibson
Writer and educator with a focus on practical home improvement knowledge.
Rate This Guide
How helpful was this guide? Click to rate: