By Andy Pasquesi, eHow Contributor
updated: May 6, 2010
Appliances with remote controls consume more electricity than you might expect.
When calculating an appliance's energy consumption, there are two types of power expenditures to consider: running power and standby power. Running power refers to the energy consumed while the appliance is in use. Standby power refers to the energy consumed while the appliance is turned off yet is still plugged into the wall. For televisions, cable boxes, stereos and other appliances to receive the "On" signal from a remote control, a small amount of electricity must be continually drawn from the outlet to power a small internal circuit to act as a receiver. Likewise, a microwave needs to consume electricity to power a circuit that "senses" when you first push the "Set Time" button. Therefore, total power consumption is defined as "[running power] x [time spent in running mode] + [standby power] x [time appliance is plugged into wall while idle]."
Difficulty: Moderate
Instructions
1
Look for the appliance's wattage rating during use. If the appliance uses an adapter to plug into the wall, this information is usually printed on the adapter's housing. If the appliance plugs directly into an electrical socket, you may be able to find the wattage printed on either the back of the appliance or on a small tag attached its power cord. Otherwise, consult the appliance's manual or the manufacturer's website for technical specifications.
2
Multiply the wattage by the time the appliance is running, in seconds. This will give you the total energy consumption, in Joules (J). For example, if a 400 W appliance runs for two hours (7200 seconds), then the total energy consumed equals 400 watts times 7200 seconds, which is 2.8 megajoules (MJ).
3
Work out the appliance's average standby power consumption. There are tables online that show the average standby powers of several different types of appliances.
4
Multiply the average standby power rating by the amount of time the appliance spends idle while plugged into the wall, in seconds. For example, if an appliance is plugged into the wall continuously (i.e. 24 hours per day) and used for two hours per day, the idle time for each day would equal "[24 hours - 2 hours] x [3600 seconds in an hour]," which equals 79,200 seconds. If that appliance had a standby power of 3.06 watts, the total standby energy consumed for that day would be "[79200 seconds] x [3.06 J/s]" or 242 kJ.
5
Add the running energy consumption (from Step 2) to the standby energy consumption (from Step 4) to determine the total energy consumption of the appliance during a given time period.
