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🕑 3 minutes read

With smart meters now almost ubiquitous among households and businesses, it’s easier to track your energy consumption day-to-day. However, these smart meters only tell you how much energy you are consuming in the property in total, not what is consuming the most energy within the property. So, how can you find out?

You could go around your house and unplug everything that’s switched on except for the device you wish to measure, then go and keep an eye on your meter with a stopwatch. You might have to wait and watch your meter tick for a while, however, so this method isn’t exactly efficient. It could, perhaps, be useful to measure the power of any devices where the plugs are difficult to reach, such as your oven or fridge, but even then, those items have inconsistent energy usage so you’d need to observe for a long time. There are other ways to measure, but before we get into that, it’s a good idea to understand how energy companies measure your consumption.

How do we measure energy usage?

It’s important to understand exactly how energy companies calculate your electricity bill. On the bill, there is a lot of information that can be quite difficult to understand, but the essential stuff that’s hidden in there is relatively simple.

Energy is measured in watts (W), but you’ll usually see it written as kilowatts (kW), which is 1000W. On your bill, the measurement your supplier uses is kilowatt hour (kWh). Confusingly, this is not the same as kilowatts per hour. A kWh is a means of measuring how fast something consumes energy. If a device generates 1 kW of power and is on for an hour, it sustains 1 kWh of energy. If you switch on a 200W light bulb, it would take five hours to get to 1 kWh of energy. Most energy companies will measure your consumption using kWh.

Take a look at your electricity bill. Take the total monthly cost and divide that by the total energy consumption.. The resulting figure is your cost per unit. It’s worth doing this calculation even if you think you know the cost per unit.

A rough estimate

If specifics and accuracy aren’t too important for you, then there is a quick and simple way to find out what your devices are using. On the packaging or on the device itself there will be a piece of information that tells you the maximum power in watts.

If you take this figure, multiply it by the duration that it has been used in hours, and then divide by 1000, you’ll have your kWh! Albeit a rough and unreliable answer, but helpful for guidance on your appliances’ energy consumption. For instance, the kettle in our office says it uses 2520-3000W (kettles are notoriously power-hungry). Assuming we take the average amount of 2760W and it’s in use for three hours a day, we can make a rough calculation for the kWh:

2760 (watts) × 3 (hours) ÷ 1000 = 8.82 kWh

If we were to look at our energy bill or use the method in the previous section, we could check how much per kWh we are charged and calculate the daily running cost of our kettle.

Keep in mind this method relies on appliances running at the wattage they have labelled, but this number is usually representative of the maximum. Most appliances use about half the shown figure.

What does a Smart Meter do?

Smart Meters are the new generation of gas and electricity meters which have put an end to estimated billing that can lead to inaccuracies or over-charging. All Smart Meters are connected to a secure smart data network, so readings can be automatically sent to the supplier on a monthly basis, or more frequently if required – this ensures that each bill you receive contains accurate billing.

Smart Meters also feature a display screen which indicates exactly how much energy you have used in pounds and pence, helping you keep track of your usage and challenge any billing discrepancies. 

Statistically, heating or cooling the building uses the most energy, followed by your water heater: 61% of energy consumption in residential properties comes from these appliances. If your goal is to reduce energy usage in your building, then check out our blog on small measures that can save you money on your energy bill!


16 Nov 2021

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