Saving Money with LED lighting

How to save ‘£240 a year’ with LED lightbulbs

The total power consumption of the 10 lights with old-style bulbs comes to 600W or 0.6kW. Electricity is sold in units of kilowatt-hours (kWh) – the amount of energy that a 1kW device uses in an hour. So each hour the 10 lights consume 0.6kWh.