kilowatt vs kilowatt hour

Reducing our energy consumption or improving our efficiency is often the simplest and most cost-effective way to reduce energy costs.

What is energy?

Your electricity bill will show energy used as kilo-Watt hours or (kWh).

What is a kWh?

A kWh is a measure of energy used over a period of time, in this case an hour. So, for example, if you had a machine that needed a kW of power to run (i.e. 1000W), and it ran for an hour, that would mean a kWh of energy had been consumed. Another example, if you had a light bulb, consuming 50W and it ran for 2 hrs, that would be 100Watt hours of energy; 20 hrs would be 1000Watt hours (or 1kiloWatt hr, or 1kWh) of energy. Note the difference between ‘power’ and ‘energy’.

Power (kW)

Is expressed in Watts or if it is a 1,000 Watts then we use the term kilo-Watt or abbreviated to kW. This represents the amount of power needed for a device at a given point in time.

Distance and Speed

You could think of power as speed. A car travels at a certain speed at a given point in time. It could be 100km/hr. That does not tell us how much it has travelled, only the speed it is doing at that point in time. Similarly the kW rating of a machine only tells us the maximum power at a given point in time.

Distance, on the other hand, refers to the overall mileage or kilometres covered. This is similar to kWh which refers to the total energy used.