Lights Off

Each time you do this action (either turn your lights off early or turn lights off when you leave a room) you will save 1.3kg of CO2

Calculation Method
Green Thing would like to do it in the dark for 3 hours:

• If you turned off all the lightbulbs ¹ in your house for 3 hours you would save: 3.71 kg (0.0527kg ² x 3 x 23.5)
• If you turned off your lightbulbs in one room for 3 hours you would save: 0.69 kg (0.0527kg x 3 x 4.4) ³
• Green Thing has reached 1.3kg of CO2 by giving weightings to the two CO2 savings of turning off your lights in your whole house and turning off the lights in just one room.
  • 20% of 3.71kg (whole house) = 0.742
  • 80% of 0.69kg (one room) = 0.557
  • 0.742 + 0.557 = 1.3kg

Footnotes

Reference	Notes
1	The average number of light bulbs in a house is 23.5 (The Energy Saving Blog http://howtosaveenergy.blogspot.com/search/label/reduce)
2	Ten 100 watt bulbs switched on for 1 hour uses 1kWh of electricity and 1kWh of electricity produces 0.527kg of CO2 so One 100 watt bulb will produce 0.0527kg of CO2 per hour. (AMEE The World's Energy Meter http://wiki.co2.dgen.net/index.php/ActOnCO2_Methodology#Grid_Electricity)
3	The average number of rooms in a house is 5.34: 23.5/5.34 = 4.4 (National Statistics 2001 Census http://www.statistics.gov.uk/census2001/profiles/commentaries/housing.asp)