Section 2: Individual LEED Credit Reviews
LEED Credit EQ-2:
designs or diffuser layouts. The process can be
seen as a means of confirming and refining initial
Increase Ventilation
design assumptions.
Effectiveness
Buildings with underfloor air delivery systems can
demonstrate credit compliance through design
narratives and drawings indicating diffuser
locations, air velocities, and the predicted air
Intent
distribution in the upper and lower stratification
Provide for the effective delivery and mixing of
zones. ADPI-type calculations are not required for
fresh air to support the safety, comfort and well-
underfloor air systems.
being of building occupants.
For the purposes of this study, it is assumed that
natural ventilation strategies meeting the LEED
Requirement
credit criteria are unlikely for most GSA building
For mechanically ventilated buildings, design
types.
ventilation systems that result in an air change
effectiveness (Eac) greater than or equal to 0.9 as
Basis for Cost Assumption
determined by ASHRAE 129-1997. For naturally
ventilated spaces demonstrate a distribution and
The Courthouse model includes an underfloor air
laminar flow pattern that involves not less than
distribution system as a GSA standard; it is
90% of the room or zone area in the direction of
therefore assumed to comply with the credit
air flow for at least 95% of hours of occupancy.
requirements at no additional cost.
(1 point)
In the Office Building model, the credit is earned
with a well-designed overhead air distribution
system. There is no construction cost premium to
Cost Impact = 1 or 2
achieve the credit; however, projects may incur
additional soft costs for performing and
documenting the ADPI calculations (see Section 4
1
2
3
4
5
of this study).
GSA
No
Low
Moderate
High
Summary of First Cost Impacts
Standard
premium,
premium
premium
premium
(no cost)
psble svgs
(<50K)
(50-150K)
(>150K)
Courthouse (New Construction, 262,000 GSF)
Practical Applications
No identified cost premiums.
Both overhead and underfloor air distribution
systems can meet the performance criteria for this
Office Building (Modernization, 306,600 GSF)
credit. For overhead (ceiling) distribution systems,
project engineers must demonstrate that the
No identified cost premiums.
ventilation designs for all the major space types in a
building meet acceptable Air Diffusion
Performance Index (ADPI) targets. ADPI selection
Additional Considerations
procedures, which address diffuser types, diffuser
spacings, and air velocities, are used as parameters
None identified.
for achieving good comfort and air mixing within a
given space. ADPI calculations, which are defined
Synergistic Credits
in ASHRAE Fundamentals Chapter 31 (Space Air
Diffusion), are often not performed or formally
None identified (with construction cost impacts).
submitted as part of a typical HVAC system
design. The ADPI parameters, however, do not
typically result in significant changes to HVAC
GSA LEED COST STUDY
135
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