How energy is measured

One of the basic measuring blocks for energy is called a Btu or British thermal unit. Btu is defined as the amount of heat energy it takes to raise the temperature of 1 pound of water by 1 degree Fahrenheit, at sea level. One Btu equals about one black-tip kitchen match. It takes about 2000 Btu to make a pot of coffee.

Energy can also be measured in joules (pronounced the same way as ‘ jewels’). One joule is the amount of energy needed to lift 1 pound about 9 inches. It takes 1000 joules to equal a Btu. It would take 2 million joules to make a pot of coffee.

Joule is named after an English physicist named James Prescott Joule who lived from 1818 to 1889. He discovered that heat is a type of energy.

Around the world, scientists measure energy in joules rather than Btu. It is much like people around the world using the metric system, metres and kilograms. Like in the metric system, you can have kilojoules: ‘kilo’ means 1000, therefore, 1000 joules = 1 kilojoule = 1 Btu.