Page 291 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

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previously noted, it may be difficult to locate monitors in this “floating” space; therefore
LEED 2009 gives some clarification regarding the location of the sampling devices for
credits requiring air quality measurements in the breathing zone in that they are located
within the horizontal planes, not necessarily the vertical planes (i.e., they are located
between 3 and 6 ft above the floor).

Special Circumstances and Exemplary Performance
There is no EP point related to IEQc1 in either the 2.2 or the 2009 version of LEED.

6.2 IEQ Credit 2: Increased Ventilation
The intention of this credit is to improve air quality by providing air exchange rates that
are higher than the minimums established in the prerequisite. However, increased air
exchange rates with outdoor rates may have an impact on energy use, so additional
strategies such as countercurrent flows for preheating or cooling may be needed to improve
both air quality and energy efficiency. Ventilation strategies should be carefully evaluated
in conjunction with energy efficiencies and impacts to maintain an optimum balance
between these two goals. IEQc2 is worth one point in both LEED 2.2 and LEED 2009.

USGBC Rating System
LEED-NC 2.2 lists the Intent, Requirements, and Potential Technologies and Strategies
for IEQc2 as follows, with modifications to reflect the changes in LEED 2009:
Intent
Provide additional outdoor air ventilation to improve indoor air quality for improved
occupant comfort, well-being and productivity.
Requirements
FOR MECHANICALLY VENTILATED SPACES (Case 1 in LEED 2009)
• Increase breathing zone outdoor air ventilation rates to all occupied spaces by at least
30% above the minimum rates required by ASHRAE Standard 62.1-2007, with errata
but without addenda (formerly the 2004 version for LEED 2.2) as determined by IEQ
Prerequisite 1. (Also, in LEED 2009, the ASHRAE 62.1-2007 addenda may be used by
project teams but only if consistently used throughout all the LEED credits.)

FOR NATURALLY VENTILATED SPACES (Case 2 in LEED 2009)
(The following requirement in LEED 2.2 to ‘Design natural ventilation systems for occupied
spaces to meet the recommendations set forth in the Carbon Trust “Good Practice Guide
237” [1999]’ has been deleted in LEED 2009 per addenda dated 12/2/09.) Determine that
natural ventilation is an effective strategy for the project by following the flow diagram
process shown in Figure 2.8 of the Chartered Institution of Building Services Engineers
(CIBSE) Applications Manual 10: 2005, Natural ventilation in non-domestic buildings.
AND
• (Case 2 Option 1 in LEED 2009) Show that the design of the natural ventilation systems
meets the recommendations set forth in the CIBSE Applications Manual 10: 2005,
Natural ventilation in non-domestic buildings (Path 1) or CIBSE Applications Manual
13:2000, Mixed Mode Ventilation (Path 2), whichever is applicable to the project space.
OR
• (Case 2 Option 2 in LEED 2009) Use a macroscopic, multi-zone, analytic model to
predict that room-by-room airflows will effectively naturally ventilate, defined as