States that heating ventilation and air conditioning systems that use 55degF (12.8degC) chilled water for space cooling have been applied successfully in several commercial and institutional facilities. When such systems use district chilled water, they in effect expand the capacity of existing district plants by making use of the plants' return chilled water (55degF, 12.8degC). Some of the systems also use hot water in the summer cooling process to regenerate a desiccant. Describes an integrated HVAC/district heating plant that uses 12.8degC district chilled water plus district hot water during the summer and compares this with 1) a conventional all-air variable air volume system linked with 45degF (7.2degC) or 35degF (1.7degC) district chilled water and 2) a cold all-air VAV system linked with 1.7degC district chilled water. Compares the three systems.

KEYWORDS: Heating, ventilation, air conditioning, district cooling, space cooling, comparing, variable volume air conditioning