This research project is focused on opportunities for achieving near-term energy efficiency gains in heating appliances, specifically integrated systems that combine low ambient heat pumps and high efficiency oil-fired boilers. The Contractor shall conduct field studies in order to better understand how these hybrid systems are currently being installed and operated. Following the field studies, an analysis effort shall be undertaken in order to quantify the effect of a heating system's components performance, sizing, and control strategies on annual energy performance. The Contractor shall then develop a Best Practices Guide for hybrid heat pump/oil-fired boiler systems. The project concludes with the dissemination of the Best Practices Guide as well as the publication and conference presentation of any technical papers developed from the laboratory evaluation.