Air-conditioning systems for laboratory buildings have always been more subject to change than conventional buildings. Constant-volume systems for laboratory buildings have adjusted to changes in laboratory building operation with periodic rebalancing. Variable-air-volume (VAV) systems are now the state of the art for laboratory buildings. With VAV and active pressurization controls, the HVAC engineer must design controls and systems to continually respond to laboratory building dynamics. Each zone in a lab has rapidly changing exhaust and heat load characteristics. Some of the design implications of these lab building dynamics are discussed.