Meeting ASHRAE 62-89 at lowest cost

This article examines why meeting the ventilation requirements of ASHRAE Standard 62-1989 while keeping energy consumption in line is not as easy as it first appears. Traditionally, HVAC design has mixed air for thermal loads and air for ventilation at the air handling unit, delivering the mixture in a common duct system to conditioned spaces. Today, the flow rate of ventilation air is prescribed by ASHRAE Standard 62-1989. For offices, that rate is 20 cfm per person. The rate for thermal loads is usually a function of room sensible load (load). A basic problem is that there is little correlation between load and occupancy in the modern office.