Many commercial and institutional buildings have significantopportunities to improve energy efficiency. However,determining which strategies to use can be challenging due tolimited funds, time and staff available to research and implementnew strategies. To help facility managers and buildingoperators determine and prioritize energy efficiency strategies,a question driven decision support system tool was developed.This paper summarizes the development, testing andevaluation of the tool. Results of the evaluation by 38 industryparticipants found that decision support systems that combineenergy and maintenance decision making processes can behelpful and useful to support decision making processes totransform existing buildings into proactively operated andmaintained, energy efficient buildings.