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Effect of Air Infiltration and Ventilation



Andrew K. Persily, Steven J. Emmerich


This chapter discusses the role of air infiltration and ventilation in building moisture transport. While water vapor diffusion can be a very important moisture transport mechanism, as discussed in other chapters, bulk air movement via infiltration and ventilation carries far more water vapor into and out of buildings than diffusion, as much as ten times or more under common conditions. Therefore it is important that we understand the phenomena of infiltration and ventilation, and the building and system features that determine the impacts on moisture transport. This chapter discusses the terminology related to infiltration and ventilation, the driving forces for infiltration, envelope airtightness and its measurement, mechanical ventilation systems, building ventilation requirements and interzone airflows within buildings. Many of these issues are well covered in Chapter 27 Ventilation and Infiltration of the ASHRAE Fundamentals Handbook (ASHRAE 2005), and therefore the material in this chapter reviews that material briefly and focuses on the more moisture-specific implications. Other valuable resources for information on infiltration and ventilation include the publications and conference proceedings of the Air Infiltration and Ventilation Centre (AIVC) (, as well as various other ASHRAE publications. In addition, ASTM has held a number of symposia over the years that have resulted in Special Technical Publications (STPs) with a range of useful technical papers (Hunt, King and Treschel 1980, Sherman 1990, Modera and Persily 1995).
Effect of Air Infiltration and Ventilation
Publisher Info
ASTM Manual Chapter in ASTM Manual, Moisture Control in Buildings,


air leakage, building envelope, design, infiltration, mositere, ventilation


Persily, A. and Emmerich, S. (2009), Effect of Air Infiltration and Ventilation, ASTM Manual Chapter in ASTM Manual, Moisture Control in Buildings, , [online], (Accessed April 14, 2024)
Created November 17, 2009, Updated February 19, 2017