Measuring standby power without overstating the savings
A device plugged in all day is not necessarily in standby all day. Separate the hours it works from the hours it waits before projecting a saving.
Name the operating state
A remote-ready television, a sleeping computer and an unloaded charger are different loads. A router providing connectivity is working even when nobody touches it. Record the state and connected accessories. Low readings may fluctuate or sit below a meter’s useful resolution.
Let energy accumulate
For a compatible plug-in device, use an appropriately rated energy meter according to its instructions. Do not adapt it to hardwired equipment. Average watts = measured kWh × 1,000 ÷ elapsed hours. A fictional 0.024 kWh over eight idle hours corresponds to 3 W. Repeat the observation if updates or network tasks wake the device.
Price the avoidable hours
At 3 W for 20 idle hours daily, annual energy is 3 ÷ 1,000 × 20 × 365 = 21.9 kWh. At an illustrative USD 0.25/kWh, that costs USD 5.475, rounded to USD 5.48. Enter 3 W, 20 hours, 365 days and 100% duty cycle in the Appliance Energy Cost Calculator. Using 24 hours counts four active hours as standby in this example.
Before disconnecting anything, check recordings, accessibility features, alarms, updates and needed connectivity. A smart plug consumes electricity too; include it in a net comparison. Measure active use separately for the device’s total cost. A small measured saving is a useful result and does not need to become a claim about the whole household bill.
Appliance Energy Cost Calculator
Worked example: Price a router and idle network accessory
Related reading: How to measure appliance energy across a full operating cycle
Reference: Berkeley Lab: standby power questions.