Insider secrets # 2

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Watts And Kilo Watt Hours Explained Simply

by | Aug 12, 2020 | Energy Efficiency, Thermal Efficiency, Utility Bills

Maurice Beinat:

Hello. I’m Maurice Beinat, Technical Director at ecoMaster with you once again. Today, I’m going to explain to you the difference between watts and kilowatt hours. Kilowatt hours are actually what your energy retailer is going to charge you for. Let’s just imagine that they charge you 30 cents per kilowatt hour. Now, watts might be a little confusing because appliances use watts, they have a rating of watts. So electricity can be thought of pretty much like water. So instead of the electricity coming out of the wires, I’m going to demonstrate with water coming out of the tap, it’s the same principle.


Let’s imagine that this jug represents one kilowatt hour, so when it’s full, you’re going to owe your energy retailer 30 cents for that. Now, in this room, we’ve got LED lights and one LED lamp uses about 10 watts. It’s not very much, it’s just the tiniest dribble. There we go. But in this room, we’ve got five LED lamps, so we’ve got to increase that somewhat. It’s now a little bit more than a dribble, but you can see it’s going to take some time to fill up a jug. The longer we leave the lights on, the more jugs we’re going to fill up over the period of the year. Let’s turn the lights off.


Now, here’s a toaster. A toaster uses about 600 watts of electricity, so the water’s going to come out a bit quicker, but we only use it for a very short time. The bread is toasted and it switches off, so that’s great. We’re not really going to fill up many jugs using the toaster. However, that’s about the same power as a high efficiency moderate-sized split system uses. So if you are using one of those to heat your home or cool your home, then we’re going to be using this for some hours at a time, and you can see that we’re going to fill up one or two jugs doing that. So the longer you use it, the more jugs you fill up and the more lots of 30 cents you’re going to owe your energy retailer.


Now, some appliances use even more power than that, electric jug, usually 2000 to 2400 watts. So look, it’s going to come out pretty fast, the electricity, and it’s going to fill up the jug really quickly, but the water’s boiled and it switches off and we’re not using any more electricity. If you’re using your electric oven, it’s probably going to be about the same as the jug, but you’re likely to use it for a lot longer. So you can see the longer you do that, the quicker you’re going to fill up the jug.


The other thing that fills up the jug in a home is standby power. So things that you don’t realise that are using power that are usually like clocks in microwaves and ovens, and of course, your internet router probably using 20 watts, maybe a little bit more, but that’s 24/7. So there’s 20 watts going 24/7, every day of the year, and you can see that over the period of the year, you’re going to fill up a few jugs doing that as well. So there you have it. We’ve filled up a jug and we owe our energy retailer 30 cents for that.


So I hope that’s been helpful. You understand a little bit more about the relationship between watts and kilowatt hours. Thanks for watching, and I’ll see you again very soon.

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