The Northwest Ductless Heat Pump Project (NWDHPP), a collabora- tion between the Northwest Energy Efficiency Alliance (NEEA) and its utility and energy partners, was established in 2008 to accelerate DHP installations in electricity-heated homes in the Pacific Northwest of the United States (NEEA, 2013; NWDHPP, 2012). NEEA (2013) esti- mates the 13,000 DHPs installed in the Northwest through 2011 saved
40.5 million kilowatt hours of electricity per year. These savings repre- sent 9% of the potential regional savings estimated by Cooney et al. (2008). This research aims to increase the understanding of DHP adop- tion in the Pacific Northwest of the United States by quantifying the ef- fect of utility-provided rebates and NEEA expenditures on the number of installations and providing forecasts of DHP installations through
2018 given various rebate and NEEA expenditure levels. Because DHPs were introduced relatively recently into the regional market for resi- dential HVAC systems, the adoption of innovation theory is applied.