‡based on 4.5 hrs a day. Household value based on 12 bulbs. Electricity prices are calculated using the UK: Value Cap (Jul 2025) electricity rate of £0.26 per kWh (incl. In recent times choosing light bulbs has turn out to be way more complicated - you knew roughly what you had been getting with a 40, 60 or a hundred wattage filament bulb. These days, power saving bulbs produce way more light, much less heat, while consuming less energy (Watts). They are available in varying applied sciences, comparable to Compact Fluorescent (CFL), Halogen and long-life LED they usually final much longer - as much as 25 years for LEDs! Defining the brightness, or light output of bulbs is altering from wattage equivalents to lumens. Lumens is an correct manner of measuring the light output of bulbs - brightness is what we understand, luminance is what we measure. However, this can be a bit of complicated! Most of us have a preconception of how brilliant a 100-watt incandescent bulb is though this could vary tremendously between tender white and clear glass bulbs.