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Activity of the day: Control your powers...

Almost all the energy- electricity or gas- you use in your home will end up as heat. So if you're trying to keep your home as cool as possible, it's worth trying to use as little energy as possible (it will also help you save money and protect the environment). Understanding how much energy different things use is a really helpful step in reducing how much heat you're putting into your house.

For example, a kettle or hairdryer (or toaster) can use a surprisingly high amount of power- while modern energy saving lights, especially LEDs, these days use very little power so won't heat your house up very much.


The first step in working out how much power different devices use is to know where your meters are.

If you're the bill payer, you probably already know... but the kids in your house may be surprised by how difficult it can be to find some meters!

Smart meters are great, but they often have a long lag time so aren't necessarily as good for looking at individual device power use as the actual meter on the mains pipe or wire that has numbers that click up as you use gas or electricity.

If you have solar panels, your meter will only show you how much electricity you're drawing from the national grid- you won't be able to measure

There are also handy little power monitors that you can plug in then plug devices into or clip onto a cable, if you're interested in being really accurate about how much electricity different appliances use!


The next step is to monitor what your power use is when "nothing" is on: Switch off everything you can, then read the meter (gas, electricity or both). Start an hour timer. At the end of the hour, read the meter.

That's your hourly baseline power consumption. You've probably got a little bit of constant electricity use from things like a cooker or microwave clock, the boiler, the wifi router- and quite a lot of power use, on and off, as fridges or freezers kick in and out of their cooling cycles.

If you divide the hourly electricity consumption by 60 you'll know how many kWh you use per minute all the time.

If all your gas appliances (boiler, cooker, fires) were off, your gas consumption should have been zero, or a little above if you have something with a permanent pilot light, If it was much above zero, it's worth double checking that everything really is off then if there keeps being much gas used, get a Gas Safe registered plumber to come and check what's going on. Gas leaks can be really, really dangerous so make sure you haven't got one!


Now you can test out any piece of kit you like: Read the meter before you start, time how long you use power with the piece of kit, then read the meter again as you finish.



Good things to try are:


  • Boiling a kettle or a pan of water (do it when you're boiling water for a cuppa or making dinner- there's no need to waste energy for this experiment!)- If you measure how much water you boiled, you'll also be able to calculate how much power it takes to boil a litre of water.

  • Watch TV for an hour, or play computer for an hour- and you can say it's for a science experiment- win!

  • Charge your phone for an hour (you may not even be able to spot this one as it may well be hidden in the baseline electricity use)

  • Have a shower (also for a science experiment... parental leverage for washing!)

  • Use a hairdrier or straighteners

  • Try out any other appliances you can find- with adult permission and supervision if they are dangerous.


If you're using electricity, take off your baseline electricity consumption from your result, then you should have a pretty accurate measurement of how much power the appliance used per minute (or hour, depending how you calculated it).


Anything involving heat (including cooling) tends to take a lot of power. Heating water- which has a high thermal mass- takes a LOT of power, so cooking, washing and heating a home are high power activities.


Lighting and electrical devices like computers and TVs tend to use surprisingly little power- but it all adds up. Something which uses only about 8-10W but uses it all the time (like a router) will use about 80kWh in a year. With electricity at about 15p per kWh, that's around £12 per year just to power the router. Appliances left on standby will be costing similar amounts- so it's worth switching anything you don't need to be on, off!


You can run the same experiment using your water meter: We don't see the amount of energy used to treat and transport water to our homes and to take away the waste (and it won't contribute to your home overheating), but running the water network uses a huge amount of power. Saving water helps to save energy too.



Energy Efficiency and appliances


If you're interested in learning more about how much energy different devices use, look for energy efficiency stickers on appliances around your home or in the instruction manuals of appliances. Instruction manuals are useful because they usually tell you the amount of energy (and water) that can be used per cycle or per hour rather than just an estimate of how much power the appliance will be used in a year. This can give you some surprising results. For example, running a dishwasher full usually uses less energy and water than handwashing the same amount of stuff- and sharing a bath between family members can use a lot less water than a power shower. For more information, have a look at the Energy Saving Trust's pages here

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