This document discusses HVAC (heating, ventilation, and air conditioning) systems. It begins by providing energy consumption statistics for a lab building and breakdowns of HVAC, heating, cooling, and other mechanical systems. Diagrams and pictures show the basic components and functions of air handling units, boilers, chillers, VAV boxes, and other equipment. It explains how different parts of the HVAC system work together to heat, cool, humidify, dehumidify, filter, and circulate air to maintain temperature and indoor air quality. The document concludes by summarizing what was covered regarding the mechanical equipment and processes used to ensure thermal comfort.