Page 391 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

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a single exposure and can be further exacerbated by repeated exposures. These health
effects could be a minor inconvenience or significantly debilitating. LEED-NC 2.2 and
2009 contain two prerequisites and nine credit areas pertaining specifically to IAQ.
Indoor air pollution results from a variety of contaminants from sources in the
outside air, equipment used in the facility, building components and furnishings, and
human activities conducted within the facility. Outside air contaminants include pollen,
dust, industrial pollutants, vehicle exhaust, and soil contamination such as radon or
even moisture, which may breed mold or other microbial growth. Facility equipment
pollutants result from dust or microbes in HVAC components, use of office equipment
and supplies, and operations of elevator motors or other mechanical systems. Building
components and furnishings contribute to poor IAQ from dust collected within carpeting
and hard-to-clean areas, microbiological growth from water damage or moisture, and
volatile organic compounds (VOCs) released from furnishings and building products.
Human activities produce indoor pollution from cleaning solvents, cooking, cosmetics,
pesticides, and VOCs from maintenance products (e.g., paint, caulk, adhesives).
Additionally, inadequate ventilation may increase the indoor pollutant levels by not
diluting the indoor sources and taking the pollutants out.
Although the primary function of HVAC systems is to control the temperature and
humidity of supply air, they are increasingly being designed for maintaining IAQ as well.
According to the EPA IAQ Guide, “a properly designed and functioning HVAC system
provides thermal comfort, distributes adequate amounts of outdoor air to meet ventilation
needs of all building occupants, and isolates and removes odors and contaminants through
pressure control, filtration, and exhaust fans.” Ultimately, there are three primary strategies
for controlling IAQ: source control, ventilation, and air cleaning.

Source Control
Source control can have an immediate and ongoing impact on IAQ by limiting
contaminant-producing materials used in the construction and furnishing of the facility
and implementing controls to reduce cleaning and maintenance products which produce
indoor pollutants. According to the EPA IAQ Guide, “source control is generally the
most cost effective approach to mitigating IAQ problems in which point sources of
contaminants can be identified.” Source control is directly addressed by one of the
prerequisites and three of the subcategories in the Indoor Environmental Quality
category of LEED-NC 2.2 and 2009. They are as follows:
• ΙEQ Prerequisite 2: Environmental Tobacco Smoke (ETS) Control prohibits or
restricts smoking within or near the facility.
• ΙEQ credits 3.1 and 3.2 require construction IAQ management plans to minimize
the potential of contaminants from the construction phase having an impact
after occupancy.
• ΙEQ credits 4.1 through 4.4 require selection of low-emitting materials for
construction products.
• ΙEQ credit 5 addresses entryway and other source area designs to minimize the
intrusion of outdoor contaminants.
There are also other design issues not specifically credited through LEED that help
prevent poor IAQ. The siting of the facility and the location of ventilation intakes are related
to source control in that these design considerations can help maximize separation from