Oct 2006
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| Kill-A-Watt meter |
How much power do typical household appliances consume? To find out, I used a "Kill-A-Watt" meter borrowed like a book from any branch of our Ottawa Public Library.
The Kill-A-Watt meter plugs into a power outlet, and then an appliance to be measured plugs into the Kill-A-Watt meter, as illustrated in the photo to the right. The power being consumed is displayed by the meter (59 watts, in the photo to the right).
The meter can also measure 'power factor' (for appliances containing motors) and energy consumption (kWh).
A watt (W) is a measure of power; power is energy per unit of time. 1 watt = 1 joule/second
A watt-hour (Wh) is a measure of energy. 1 watt-hour = 3600 watt-seconds = 3600 joules. Electrical energy is billed by the kilowatt-hour (kWh), ie., thousand watt-hours.
Thus a 60W traditional incandescent light bulb burning for 2 hours uses 2h * 60W = 120 Wh = 0.12 kWh of energy. One kilowatt-hour (kWh) costs about $0.06 in Ottawa today. That's cheap financially, but energy production has social & health costs that aren't included in that $0.06/kWh, such as air pollution (which is said to cause thousands of premature deaths annually in Ontario, and property damage, eg., due to acid rain). Just changing one light bulb (from ordinary incandescent to LED) in your house makes a difference.
Here's what I found out, using a Kill-A-Watt meter borrowed from the library:
| Device | Watts | |
|---|---|---|
| Kettle | 1433 | |
| Microwave | ||
| Stand-by (clock) | 2 | |
| Running (high) | 1380 | |
| Refrigerator (old, replaced) | ||
| Idle | 0 | |
| Running | 114 | |
| Dehumidifier | ||
| Fan only | 47 | |
| Dehumidifying | 521 | |
| Vacuum cleaner | 753 | |
| Washing machine | ||
| Filling | 6 | |
| Agitating | 440 | |
| Pumping | 340 | |
| Spinning | 780 | |
| Fan ($75 'turbine' type) | ||
| Low | 57 | |
| Medium | 75 | |
| High | 97 | |
| Electric razor | 3 | |
| Stereo (old technology) | ||
| Off | 2 | |
| Normal volume | 24 | |
| Loud | 27 | |
| Stereo (new technology) | ||
| Off | 3 | |
| Normal volume | 11 | |
| Lamp | ||
| 60W incandescent bulb | 63 | |
| Equiv compact flourescent bulb | 14 | |
| Device | Watts | |
|---|---|---|
| Piano (electric) | ||
| On, not being played | 13 | |
| Being played | 14 | |
| CD player | 2 | |
| Telephone | ||
| Off-hook | 0 | |
| Speakerphone | 1 | |
| Answering machine | 2 | |
| Laptop computer | ||
| Off, full charging | 50 | |
| Off, trickle charging | 27 | |
| Booting | 33 | |
| Windows (idle) | 23 | |
| Desktop computer | ||
| Off | 6 | |
| Memory test | 124 | |
| Windows (idle) | 78 | |
| Viewing DVD | 98 | |
| CRT computer display | ||
| Stand-by (computer off) | 2 | |
| 1024x768 mode | 80 | |
| 1600x1200 mode | 104 | |
| DSL modem + external router | 10 | |
| Laser printer | ||
| On, awaiting work | 14 | |
| Printing | 350 | |
| Battery charger | 9 | |
| Electric lawn mower | 550 to 720 | |
The appliances that are the big electricity users (eg., range/ovens, clothes dryers, air conditioners, hot water heaters) have 240 VAC plugs, which are incompatible with the Kill-A-Watt meter. However, here are some rough estimates from the web:
| Device | Watts |
|---|---|
| Range/oven | ~7000 |
| Clothes dryer | ~3000 |
| Air conditioner | ~2500 |
| Hot water heater | ~5000 |
Jim Elder
Ottawa, Canada