I have a new toy. It’s called a Watts up?, and it will measure the watts used by anything with a plug, up to about 2200 watts. It will calculate watt hours, as well, which is essential for appliances that cycle on and off. Watt hours are what you and I and the environment pay for. Quite simply, a 1 watt device running for an hour has used 1 watt hour. The electricity meters on houses measure kilowatt hour, or 1,000 watt hours, and that’s what we pay for in our electricity bills. For each kilowatt hour we use, Eskom sends about 1 kg of carbon dioxide into the atmosphere.
I’ve been playing with my toy for about a week, and I now have a good idea of how much electricity is used by what.
Here, in no particular order, are some of my findings.
•Washing Machine: 214 watt hours for full load. My mother-in-law always believed that clothes fare better in a cold wash, so we have always set our washing machine on cold. (Who am I to argue with my mother-in-law?) The washing machine is rated at 2360 watts, so it might burn out my Watts Up meter if I tested a hot load, but my calculations are that if we washed in warm or hot water, that number would rise by 10 times.
•Philips 29-inch CRT Television. 73 watts on, zero on stand-by. You won’t find a big flat-screen LCD or plasma TV that uses anywhere near that little.
•DSTV Personal Video Recorder PVR: 29 watts. This is worse than it looks. Forget the fact that the PVR tells you it’s “going to sleep,” or “coming out of sleep.” It uses 29 watts all day every day, three-quarters of a kilowatt hour per day, 270 kWh per year. What irritates me is that the designers could have engineered a PVR that powers down the hard drive when it’s not needed, as my laptop does every time I stop using it for several minutes.
•Microwave Oven: 0.8 watts on standby, 1480 watts cooking. Far more relevant is the watt hours to heat or cook food compared to an electric stove or oven. I used just 18 watt hours to poach an egg in a microwave egg poacher I once bought in the U.S. Even a small 1000 watt stove plate would use 5 times as many watt hours to heat for 3 minutes. Standby consumption adds up to 19 watt hours a day. That’s worth unplugging if going on a long holiday, but otherwise not much of a drain for an appliance used regularly. A bigger concern is leaving the door open, since the light inside uses 25 watts, which could easily surpass the consumption from heating and cooking if you leave it open often.
•Philips digital picture frame: 7 to 8 watts on, zero off.
•Rotel Stereo Amplifier and CD Player: 51 to 56 watts. That may not sound like a lot, but here’s the shocker: they draw 51 watts even if no music is playing. If I forget to turn them off after the music stops playing, they will burn through more than a kilowatt hour a day. Since I try to use less than 15 kWh a day total at my house, that’s significant. I’m very careful to turn if off since learning this. This amp is old. I suspect that newer and lower-fidelity stereos use less on standby.
•HP LaserJet 4L printer: 100-140 watts while printing, 4 watts on idle. It is a known fact that laser printers use more electricity than inkjets when printing. But for home printers, the amount of time spent printing should be so low that this is irrelevant. The 4 watt consumption on idle is unacceptably high, but this printer is at least 15 years old. Modern printers would have much lower stand-by consumption. I’ve starting using a power strip under my desk to switch off the printer when I’m not using it. Over the course of a year, this will save 35 kWh and more carbon dioxide emissions than burning at entire 9 kg cylinder of LP gas for braaiing.
•Yamaha Electric Piano: 2.6 watts when playing. 0.8 when turned off. I was surprised how low the consumption is in use. I suspected that it used even more when off, because I can feel the transformer is always warm. Still, it’s high enough for something that is used infrequently that I switch it off at the wall.
•220/110 Volt Transformer: 22.6 watts when not in use. It’s amazing how much electricity a thing can use for doing absolutely nothing. This is a heavy-duty transformer that I use because I brought several kitchen appliances from America with me when I moved to South Africa. I have become obsessive about unplugging it when I’m finished using it.
•Fan: 33 watts. A Logik standing fan, rated at 45 watts a used 33 watts on high, 31 watts on medium, and 29 watts on low. Next time an air conditioning salesman tells you that air conditioning is “efficient,” ask him if it uses more than 33 watts.
•LG 300 Litre Refrigerator-Freezer: 2.5 kilowatt hours per day. I have since learned that in cooler weather and with the vents cleaned, it uses 1.5 kWh per day. This is still about 10 percent of my total household electricity consumption, and it’s a small fridge with an A rating for efficiency from the European Union.
•Hot Water Solar Panel Pump: 31 watts. If my panels are heating water about 7 hours a day, the pump uses 0.2 kWh per day. That’s higher than I expected. If I had a more typical setup, with horizontal water storage tanks directly above the panels, they would use no electricity for pumping, working off the thermosiphon effect. But I’m convinced that having large, vertical storage tanks inside my house prevents enough electrical backup water heating to far outweigh the 0.2 kWh for the pump. Just raising the water inside one of my 300 litre tanks by one degree Celsius would require far more electricity than the pump uses in a day.