Work out energy savings from led instantly with clear inputs, formula shown and shareable results.
Swapping twelve 60 W incandescent lamps for 8 W LEDs used five hours a day saves 1140 kWh a year - an 87% cut in lighting power - and avoids about 239 kg of CO2 at a 210 g/kWh grid. LEDs also last 25,000 hours against 1000 for incandescent, so the replacement saving compounds.
Annual saving
kWh = (old W - new W) x hours/day x 365.25 x lamps / 1000
Carbon saving
kg CO2 = kWh x grid intensity
A good 8 W LED produces about 800 lumens, matching a 60 W incandescent. Compare lumens rather than watts when replacing.
Marginally - incandescent waste heat contributed to space heating in winter, but it is a very expensive way to heat a room.