Energy units are represented in units of kWh’s and different energy sources are associated with different factors of CO2.
CO2 emission factors for conventional energy sources:
1kWh Mains Natural Gas: 0.194 kgCO2
1kWh Grid Supplied Electricity: 0.422 kgCO2
1kWh Grid Displaced Electricity: 0.568 kgCO2**
Typical Annual Benchmark Figures*** for renewable energy sources:
1 kWp of solar PV produces 800 kWh of displaced electricity
1 m2 of solar thermal produces 300-400 kWh of gas savings
1 kWe of wind turbines ranges between 500 kWh (urban) to 1,500 kWh (rural) of displaced electricity
Carbon vs. Carbon Dioxide emmissions conversion
Caution should be taken with the suffix depicted by Carbon (C) and Carbon Dioxide (CO2) such as kgC/kWh or kgCO2 as they differ in mass.
To calculate the amount of CO2 from C, multiply by 44 then divide by 12 (the corresponding atomic masses).
*Emission factors taken from 2006 Part L2A Building Regulations
**Grid displaced electricity comprises PV, Wind etc generating energy at building and represents the CO2 resultant of peak-power electricity generation from the grid.
***Figures from EST guidance p17 “Meeting the 10 per cent target for renewable energy in housing – a guide for developers and planners”