Greening my House

No, this posting is not about a civil rights movement for the undead. Vampire power is the power that your electrical and electronic equipment uses when it is turned off.

I can just hear what you are thinking, “Wait a second. Didn’t you just write “turned off”??? If the devices are turned off, why would there be any power usage?”

The reasons are twofold.

First, many devices are not really off when you turn them off. No, really! They actually go into a low power usage “standby” mode. The whole purpose of this mode is to wait for you to turn them back on again. That means they have to use a little bit of electricity to power the button or infrared device that turns them back on again.

Second, some devices have a transformer attached to step down the 110V alternating current electricity coming out of your wall socket into nice, gentle 5 to 12V direct current electricity that can be used directly. The problem is because of the way many transformers are designed — they use electricity even when things are not plugged in to them. They can use as much as 5% of their regular fully-loaded amount while sitting there unused. This energy is dissipated by way of heat, which is why transformers get hot.

Five percent doesn’t sound like much… but when you add it up over the whole of the US, it can mean billions of kilowatt hours of wasted energy — all while doing nothing!

Kill-A-Watt

No, it’s not another reference to the undead. A kill-a-watt is a device by P3 International that measures electrical usage of anything that is plugged into it. You plug the kill-a-watt into the socket, and then plug your device into the kill-a-watt, and it can tell you how much electricity is being used by that device.

Our friends Eric and Anne have one of them and they let us borrow it recently. I went around and analysed the electricity usage for all sorts of things that we plug in.

The results are tabulated on the page “Usage at our house” listed in the column to the right.

The total is nasty:

Devices that are supposedly “off”: 7.5W
Devices left on all the time: 126W
Total: 133.5W

Multiply that out to find how much it costs:

133.5 W = 0.1335 kW
0.1335 kW * 24 hours a day * 365 days a year = 1169 kWh a year
1169 kWh * $0.22 /kWh = $257 a year!

Woah! That’s a lot wasted on doing nothing!

Now, to be fair, a few things must be left on all the time, or else they are not useful. These are:

• tivo
• dsl modem
• wireless router
• cordless phone
• fridge

The total usage of these devices is 66W. Calculating out, those devices use $127 a year. That still means that there are $257 – $127 = $130 worth of devices doing nothing.

In the coming months, I will be finding ways of reducing this usage.

Please note that the numbers above don’t include all the things that are connected to the electrical mains but which are not pluggable, so I cannot use the kill-a-watt to measure their electrical usage. Things that are on all the time but which are not measurable include:

• garage door opener
• garden lights
• main refrigerator
• trash compactor
• washer
• dryer
• dish washer
• stove/oven

Fortunately, many of those devices have physical switches, so they only use electricity when they are turned on and operating. It would not make any fiscal sense to replace any of them just for the purposes of reducing power usage. However, in the future, if any of these things need to be replaced, energy efficiency will be one of the top criterion for selecting the replacements.