Introduction
In Chapter 3, we covered two factors that affect comfort and activity, temperature and humidity. In this chapter, we will be discussing an additional factor, Indoor Air Quality, IAQ. The maintenance of indoor air quality (IAQ) is one of the major objectives of air-conditioning systems because IAQ problems are a significant threat to health and productivity.
Those who study Indoor Air Quality consider the makeup of indoor air, and how it affects the health, activities and comfort of those who occupy the space.
The primary factors that influence and degrade IAQ are particles, gases, and vapors in the air. Maintenance of good indoor air quality is a significant issue to both the HVAC design engineer and to those who maintain the system sub- sequent to its design and installation.
To deal properly with the issues of IAQ, it is important to be aware of The various types of pollutants and contaminants, their sources and their effects on health.
The factors that influence pollutant and contaminant levels in buildings
e The sources of pollutants.
e The ways pollutants can be absorbed and re-emitted into the building spaces.
Ways of maintaining good IAQ by
e Controlling the source of pollutants within the space.
e Using filters to prevent pollutants and contaminants from entering the space.
e Diluting the pollutants and contaminants within the space.
ASHRAE has two ANSI approved standards on ventilation:
ANSI/ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality1 (Standard 62.1-2004) which deals with ventilation in “all indoor or enclosed spaces that people may occupy.”
ASHRAE/ANSI Standard 62.2-2004 Ventilation and Acceptable Indoor Air Quality in Low Rise Residential Buildings2 (Standard 62.2) which deals, in detail, with residential ventilation.
The scope of Standard 62.1-2004 deals specifically with “Release of moisture in residential kitchens and bathrooms,” while Standard 62.2 deals with “mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in low-rise residential buildings.”
Like other ASHRAE standards, these are consensus documents, produced by a volunteer committee of people who are knowledgeable in the field. The standards have been publicly reviewed and are continuously re-assessed. They have force of law only when adopted by a regulatory agency, but are generally recognized as being the standard of minimum practice