What does 100W cost per year?

It used to be that a single, bright lightbulb would consume 100 Watts.

Modern bulbs and most other devices are much more efficient these days, but we have more of them. The energy demand adds up. While a single LED bulb is around 5W, a set of downlighters, or kitchen cabinet LEDs or wall lights might be using as much as the old fashioned incandescent bulbs did.

A modern 50″ TV uses about 85W, add a soundbar and you are at 100W or more.

So what does 100W cost to run?

For every 100W, running 24 hours a day, the annual cost looks like this:

• Energy use: 100W = 0.1 kW.
• Hours in a year: 365 x 24 = 8736
• Electricity cost per kWh: £0.29
• Annual cost: 0.1 x 8736 x 0.29 = £253.35

It’s definitely worth turning stuff off when you aren’t actively using it.