Energy Information

Data Sources

Our estimate of the impact of real-time energy feedback on carbon emissions is based on the following sources:

• Home electricity use: The U. S. Energy Information Administration estimated in 2001 that there were 107 million households in the United States using a total of 1140 terawatt-hours (TWh) per year. That gives an average of 10.6 megawatt-hours (MWh) per year per household.
• Carbon emissions from residential electricity: According to the U. S. Environmental Protection Agency, the National Average Emissions Rate for 2005 was 712 g CO₂ per kilowatt-hour (kWh).
• Electricity saved with real-time feedback: There have been several studies of feedback's effects on energy use. Sarah Darby's review of the literature, The Effectiveness of Feedback on Energy Consumption (pdf) , estimates savings between 5 and 15% from direct feedback.
• Carbon emissions from cars: Again according to the EPA, a typical car is driven 12,000 miles per year, the average fuel economy of a passenger car is 23.9 miles per gallon, and a gallon of gasoline produces 8.8 kg of CO₂.

Based on these figures, we get an average of 7.5 tonnes of CO₂ emitted per year per household, and 4.5 tonnes of CO₂ emitted per year per conventional car. So, 10% energy savings for 6 households would reduce carbon emissions by about the same amount as taking one conventional car off the road.