What’s Watt?

What’s Watt in the world of electricity?

It’s all very well reading about saving electricity and anyone can understand that to do so you just have to flick off a switch. But, understanding the terminology and calculating costs can be a chore. This short explanation should remove some of the mystery and help you save more effectively.

 

The Watt, kiloWatt and kiloWatt/hour explained

Energy released by electricity is measured in watts. In a home every appliance has an electricity rating. This, usually found on the back of the appliance, tells the user how many watts that particular appliance uses in an hour. (If, for example, a lamp uses 100 Watts, it will use this amount of electricity in an hour.)

One-thousand Watts (1 000 W) equals one kiloWatt (1kW). When you are charged for electricity, your bill will usually tell you how many units were used during the month. One unit of electricity is exactly equal to 1 000 watts of power used for 1 hour- or kWh, which suppliers use to determine your costs. (Your lamp using 100 Watts will therefore use 0.1 kW in an hour when it’s usage is monitored by your home’s electricity meter.)

To determine what the lamp costs you to run, you simply perform the following calculation:

unit cost x power consumption in Watts divided by 1 000

A 100 watt lamp in a house paying 44.39 cents per unit (kWh) would cost:

44.39 cents x 100w, divided by 1 000 = 4.44 cents an hour.