LED lighting energy savings depend on the wattage you replace and how long the lights run. Compare equivalent light output first, then calculate electricity use with your own hours and tariff.
In this guide
List the lighting you use
Start with a room-by-room list of the lights you use most. Record the lamp or fitting wattage from accessible packaging or product details, the number of fittings and typical daily hours. Do not open fixed fittings to look for a driver label.
Use our lighting design guide to connect energy choices with room use, light colour and controls. An efficient fitting still needs to deliver the light you want.
Compare lumens before watts
Lumens describe light output; watts describe electrical input. Compare candidate lamps or fittings at a suitable light output, then consider beam angle, colour temperature and dimming. A lower-wattage product that leaves the worktop dark is not a like-for-like replacement.
Our warm white and cool white guide helps with colour choice. For a kitchen, use the kitchen lighting plan to think about where the light falls.
Calculate annual electricity use
Use this calculation for each group: watts × number of lights × hours per day × days used per year ÷ 1,000 = annual kilowatt-hours (kWh). Calculate the existing and proposed groups using the same hours, then subtract the proposed use from the existing use.
| Illustrative inputs only | Existing group | Proposed group |
|---|---|---|
| Number of lamps | 6 | 6 |
| Watts per lamp | 50 W | 8 W |
| Use | 4 hours daily, 365 days | 4 hours daily, 365 days |
| Calculated annual use | 438 kWh | 70.08 kWh |
This hypothetical example gives a difference of 367.92 kWh per year. It assumes the proposed lamps provide suitable light and are compatible with the fittings. It is not a prediction for your home.
Apply your own electricity tariff
Multiply the kWh difference by the relevant per-kWh rate on your bill. For time-of-use pricing, split the hours across the rates you actually pay. Fixed daily charges do not fall simply because lighting uses less electricity.
Compare the calculated electricity difference with the installed upgrade quote. Include any required fittings, drivers, dimmers and labour. Changing your usage changes the result, so keep the assumptions beside the calculation.
Check the complete fitting
An LED upgrade can involve more than changing a lamp. Existing transformers, drivers, dimmers and enclosed fittings need a compatible solution. We can assess the combination and advise whether lamps or whole fittings suit the job.
For lighting installation, bring your room list and preferred light output. Where flickering is the reason for replacement, have the fault assessed before using an energy calculation to choose new equipment.
Questions about LED energy savings
Does lower wattage always mean a better replacement?
Compare suitable light output and distribution first. Wattage is useful for calculating electricity use once you have a fitting that lights the space properly.
Can I use the example savings for my quote?
Use your own lamp count, wattages, hours and tariff. The example shows the calculation method and does not include an installation price.
Bring us your most-used lighting groups and the changes you want. We can help you choose compatible fittings and scope the installation before you compare the cost.