Room BTU Requirements

BTU

• BTUs are units of heat energy. One BTU is approximately equal to the heat required to raise the temperature of a pint of water by a single degree Fahrenheit. Most heating appliances, including furnaces, fireplaces, boilers and space heaters, have a BTU rating equal to the heat they generate over the course of an hour. All living areas also have a BTU requirement --- the amount of energy it takes to keep them at a comfortable temperature.

Matching Requirements

• Purchasing a heater with a BTU output that closely matches your room's BTU requirements is very important. Buy too weak an appliance and your room will become chilly during the coldest days of the year. Get one that's overly powerful and you'll be left with either an overheated room or a heater that shuts on and off frequently, wasting energy.

Calculating by Hand

• You can calculate the BTU requirements of your room using a simple mathematical formula. Simply measure the length, width and height of the room and multiply the three numbers together to find the cubic footage. Multiply this by three if the room is a kitchen, four if it's a bedroom or five for any other type of living space. Add 15 percent if the room adjoins the north wall of your house and 20 percent if it contains large windows. A final 10 percent for general heat loss will give you the room's BTU needs.

Calculating Online

• Several online tools, such as those found on the Herman-Nelson and HearthNet websites, will automatically perform the calculations necessary to determine your room's BTU requirements. Though each one differs slightly from the others, usually you only need to enter the data required by the calculator and press a button to see your results.