Describes an innovative HVAC system designed for a laboratory with an area of about 190m² (2,040ft²), with low ceiling height and little ceiling space for ductwork. These constraints led to an aggressive design approach resulting in developing design diversity based on allowing any four of the ten fume hoods to operate in the fully open sash position and all other hoods at the 20% open sash position. An audible alarm sounds if at any time the sash on the fifth hood is opened more than 20%. Describes the variable air volume system with reheat selected to achieve design and operating diversities and notes operating energy and construction costs. Compares in a table various elements of the variable air volume/reheat and the constant volume/reheat. Gives measurement results showing the satisfactory operation of the system.