Page 392 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

DoD Sustainable Construction and IAQ 353

outdoor sources of contaminants. Additionally, it is important that safeguards, policies, or
practices be put in place with sufficient related enforcement to ensure product selection for
cleaning and maintenance activities conducted throughout the life of the facility that utilizes
low-emitting solutions and compounds. It is evident from the number of credits available
within LEED that source control is an important part of IAQ management, although there
are additional measures that need to be considered for both the design and the operation of
facilities to maintain a healthy IAQ.

Ventilation
The common catch phrase “dilution is the solution to pollution” has actual application
as a control mechanism for IAQ. Increasing the amount of outdoor air brought in
through the HVAC system is another approach to lowering the concentrations of indoor
air contaminants. According to the EPA IAQ Guide, some of the main design
considerations for HVAC systems to dilute indoor air contaminants are to “increase the
total quantity of supply air (including outdoor air), increase the proportion of outdoor
air to total air, and improve air distribution.” To measure this effectiveness, “the term
‘ventilation efficiency’ is used to describe the ability of the ventilation system to
distribute supply air and remove internally generated pollutants.” LEED-NC 2009
stresses proper ventilation through IEQ Prerequisite 1: Minimum IAQ Performance
which establishes ASHRAE 62.1-2007, Ventilation for Acceptable Indoor Air Quality,
as the standard ventilation system design. Additionally, IEQ credit 1 provides for
monitoring CO concentrations as a means to ensure ventilation is maintained as
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designed, and IEQ credit 2 recognizes efforts to increase ventilation above the ASHRAE
62.1-2007 standard. Special ventilation system considerations for establishing negative
pressure in specific spaces are addressed within IEQ prerequisite 1 for ETS control and
IEQ credit 5 for indoor chemical and pollutant source control. The EPA IAQ Guide also
specifies that although introduction of sufficient outdoor air for proper dilution of
contaminants is key, “inadequate distribution of ventilation air can also produce IAQ
problems.” This comment emphasizes the importance of commissioning and proper
testing and balancing of HVAC systems for enhancing ventilation efficiency. EA
prerequisite 1 and EA credit 3 relate to the commissioning requirements, and EA credit
5 addresses proper measurement and verification. Although these credits are within the
Energy and Atmosphere category of LEED-NC 2009, they have direct contributions to
IAQ as well.
Lodging facilities have other unique considerations when it comes to proper
ventilation for good IAQ. For example, the use of decentralized HVAC systems is a
fairly common practice; however, design solutions need to be evaluated for other cost-
effective alternatives that still allow some degree of occupant control while maintaining
minimum ventilation requirements. Another concern for lodging is proper ventilation
of cooking equipment and fireplaces, if installed. Since not all sources of indoor air
pollution can be eliminated, proper ventilation is critical to maintaining good IAQ
within a facility. LEED contains several direct and related prerequisites and credits that
emphasize the importance of ventilation for IAQ management.

Air Cleaning
Air cleaning, or filtration, should not be considered a primary control mechanism for
IAQ management since it is most effective when used in conjunction with either source
control or ventilation. Filtration has two main functions—removing contaminants from