1. Calculate your electricity consumption:
Find the circuit wattage for your luminaire and multiply this figure by the number of luminaires on the lighting circuit.
Divide the wattage of your lighting circuit by 1000 to convert in to kW.
Multiply the kW of your lighting circuit by the number of hours that the luminaires will be on for the year to find the total electricity consumption in kWh per year.

2. Convert kWh into CO2 produced:
Government figures provided by DEFRA show that 0.53kg of CO2 is produced for every 1kWh of electricity consumed. Therefore, multiply annual electricity consumption (kWh) by 0.53kg to calculate the CO2 produced per year.