The document discusses HVAC operation and maintenance. It explains that HVAC systems provide thermal comfort and indoor air quality. Proper HVAC O&M practices are needed to maintain high performance over the lifetime of the building. Key aspects of HVAC O&M include regular maintenance according to schedules, cleaning of filters and components, and ensuring control systems operate correctly. Proper design, documentation in operations manuals, and adherence to maintenance schedules are important for high quality HVAC O&M.