1. Residential energy consumption survey: preliminary housing characteristics tables,2005
2. Residential energy end-use splits by fuel type (quadrillion BTU). Table 2.1.5,2008
3. Figure 2.5 household energy consumption and expenditures, consumption by end use, 2005. Annual energy review,2009
4. Electricity use in California: past trends and present usage patterns;Brown,2002
5. U.S. Census Bureau. Characteristics of Housing. Available from: http://www.census.gov/const/www/charindex.html; 2009.