Steady-state calorimetry method to measure the ventilation rate in an airspace

In many cases, airflow rates through microenvironments (e.g., zones within a room) are unknown and vary considerably from mean room (macroenvironmental) conditions. A steady-state calorimetry method to estimate the ventilation rate in an airspace is described. The method can be applied not only to enclosed, mechanically ventilated airspaces but also to those less-enclosed airspaces such as a room with a door open or a zone within a room. The method is more appropriate for small airspaces (e.g., zones within a room) where thermal capacitance effects are of little influence. Large airspaces usually have large heat capacitances, which can result in failure to reach a steady state because of the superimposed heating, ventilating, and air-conditioning (HVAC) system and diurnal temperature fluctuations. Limitations of the steady-state calorimetry method are also discussed.