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A guide to kWh

The Kilowatt-hour is unit used by energy companies to determine how much you are charged, understanding what it represents can help you to reduce your energy bills.

What is a Kilowatt-hour?

A Kilowatt-hour (kWh) is the standard unit of measurement used by energy suppliers for both electricity and gas. According to the CRU, the average dual fuel customer uses 4,200 kWhs of electricity and 11,000 kWhs of gas per year.

But what exactly is it? Well basically, a kWh is the amount of energy you would use if you kept a 1,000 watt appliance running for an hour. So, for example, a 1,000 Watt electric heater left running for one hour uses 1 kWh of energy, while you would need to have a 100 watt light bulb switched on for 10 hours to use 1 kWh of energy.

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What is a Kilowatt?

A Kilowatt (kW) is a measurement of power equal to 1,000 Watts. Put simply, Kilowatts describe how much energy an appliance is using at any given moment, while a Kilowatt-hour describes how much energy it has used over a period of time.

How do Kilowatt-hours apply to energy from gas?

According to Electric Ireland, your gas meter measures your gas usage in either cubic metres or cubic feet, depending on the meter. In order to convert this measurement into kWh, energy suppliers use a ‘conversion factor’, which is published on your bill.

So what does 1 kWh power represent?

This may all seem a bit abstract, but to give you a bit of context, here’s the amount of energy used by some of the most common household appliances:

  • Washing Machine. Typically, washing machines with a decent energy rating use around 1 kWh per cycle. Washing at as low a temperature as you can will cut down on the amount of energy used.
  • Dishwasher. Modern dishwashers are pretty energy efficient, using between 1 and 1.25 kWh per cycle. Only using the dishwasher when it is full (not for half loads) will make it more energy-efficient.
  • Dryer. The dryer is one of the more expensive appliances in our homes, using around 2.5 kWh per hour of drying. It might be an idea to hang clothes first whenever possible and just use the dryer sparingly to finish the drying.
  • Fridge-freezer. Modern fridge-freezers actually use relatively few kWhs, with the typical fridge-freezer using less than 1 kWh per day. Ensuring the fridge-freezer is not too full - and making sure it’s at the right temperature - will make it run more efficiently.
  • Oven. This is one of the most expensive appliances in the home - using an electric oven can cost around 2 kWhs per hour of cooking. Some people suggest cooking two meals at one go to make the most of the oven when you do have it turned on. Also, if you have a microwave, you would be much better off cost-wise using this, rather than the oven, for reheating meals.
  • Kettle. Perhaps one of the most important appliances in any Irish home, the kettle can often be boiled multiple times a day to ensure a cup of tea is never far away. Each time we boil a kettle, it can use up to 0.25 kWhs.

How much does a Kilowatt-hour of energy cost?

How much you pay per kWh of energy you use will depend on the energy tariff you’re on, and - if you have a day and night meter - what time the energy was used.

To put it simply, the unit rate you see on your energy bills is the cost you pay per kWh you use.

Can I cut back on my energy consumption or save on the unit rate I pay?

Yes. The quickest and easiest way to save money on your energy bills is to switch to a discounted tariff, which will give you a discount on the unit rate you pay. At the moment, the average dual fuel customer who is currently on a standard tariff can save up to €487 by switching.

If you are not free to switch at the moment, you can still save by cutting back on your consumption. Our top energy-saving tips can help you get started.

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