The purpose of this report is to provide a summary of Washington’s single-family home energy use based on the Northwest Energy Efficiency Alliance’s (NEEA) 2011 Residential Building Stock Assessment (RBSA) findings. It is accompanied by three other state-specific reports for Idaho, Montana and Oregon. Each state-specific report includes overall housing utility and energy statistics, and details the type and efficiency of housing components including windows, insulation, appliances and heating fuel types within each region of each state. The state-specific report findings are largely from the 2011 RBSA study, except where supplemental data sources have been noted.