Commercial buildings have their own unique energy systems, ownership structures, and decision-making processes. They also have striking opportunities to save energy by installing smart technologies. Beginning where our previous Smart Buildings study left off, this report takes a deeper dive into four commercial building types: offices, retail, hotels, and hospitals. We detail costs and energy savings for these subsectors, describe the nonenergy benefits of smart technologies, and discuss the challenges to their widespread adoption. We conclude with recommendations for energy efficiency programs, government, and industry.