Your need-to-know guide to understanding kilowatt hour
kWh: What is a Kilowatt Hour?
Whenever you switch on the lights in a room, power up your appliances or heat your home, you’re using energy to do this.
Think of the energy that you are using as a product that you pay your gas or electricity company to supply to you. There needs to be a system in place so that your energy provider can price the energy that you use, ensuring it is charged for fairly.
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How much energy your household will use
The amount of energy you will use in your house depends on a variety of factors, such as the:
- size of your home,
- number of residents,
- percentage of time spent there,
- energy efficiency.
To put this measurement into perspective, you can review the average estimates of energy consumption reported by the energy industry:
Small households of just one or two people who use a modest amount of energy will consume around:
- 2,000 kWh per year of electricity
- 9,000 kWh per year of gas
Medium households, such as a small family living in a three-bedroom home, will consume around:
- 3,200 kWh per year of electricity
- 13,500 kWh per year of gas
Large households with occupants who spend a lot of time at home and include four or five bedrooms will consume around:
- 4,900 kWh per year of electricity
- 19,000 kWh per year of gas
How far 1 kWh can go
The difference between kW and kWh
A kilowatt, or kW, is equal to 1,000 watts. Using watts and kilowatts helps us to record and communicate how powerful any given appliance is, such as an oven, shower or washing machine. Rather than a measure of energy, this is a measure of power.
To communicate a measurement of energy, you need to work in kilowatt-hours (kWh). This tells us precisely how many kilowatts is required to power an appliance for any given time.
Let’s say an appliance uses 1,000 watts, or 1 kW, of power to work. It is left running for approximately one hour. That’s one kilowatt of energy used in an hour, which is equal to 1 kWh. If you used that same appliance for four hours, you will have used 4 kWh of energy.
Knowing how to differentiate between kW and kWh will help you dig into your energy bills and discover which appliances are using the most energy.
Each household appliance will also come with a power rating, usually labelled on the back or bottom of the appliance or contained on its packaging. The power rating tells you how much electricity the appliance needs to work, and should also be available online, so it’s worth checking the manufacturer’s website to find out the rating if you can’t find this information elsewhere.
Whilst you might lean towards household utilities using lower wattages, it’s worth doing your research before you commit, because it can be more complex than it seems. Some appliances that require more power to function are also more efficient than low watt equivalents. This means that, in some cases, higher wattages can translate to less energy consumption overall.
Similarly, some energy-efficient appliances that run at a much lower wattage for longer periods will cost less than high power alternatives. There is no simple, definite rule that applies to all of your utilities. However, aiming for energy efficiency wherever possible will help you to lower your energy consumption and reduce your bills.