Is it worth replacing every bulb in the house with LEDs?
Equal light output is the fair unit, so brightness is held constant.
Compared on: one bulb, 1,000 hours of light at 800 lumens
Incandescent (60 W)
13 kg CO₂e60 kWh of electricity for 1,000 hours at the UK grid factor.
Source: DEFRA/DESNZ grid electricity factors
Halogen (43 W)
9.0 kg CO₂e43 kWh for the same light.
Source: DEFRA/DESNZ grid electricity factors
LED (8 W)
1.7 kg CO₂e8 kWh, plus a small manufacturing share spread over a ~25,000 hour life.
Source: DEFRA/DESNZ grid electricity factors
What this means
- An LED uses roughly 1/7th of the electricity of an incandescent for the same light.
- Across a 20-bulb home used 3 hours a day, the swap saves around 240 kg CO₂e a year.
- Manufacturing is a rounding error next to the electricity saved.
Your own number, not an average
Averages answer the question; your own footprint tells you what to change first. The calculator takes about two minutes and needs no account.
Figures are averages drawn from public databases and peer-reviewed LCA work; see our methodology for how each factor is applied.