Executive Summary
The cost impacts may not be directly transferable to
many "market-rate" commercial developments. A
other project types or building owners. These issues
number of GSA's design criteria are consistent with
are reviewed in greater detail in the "Cost Estimate
LEED credit requirements and therefore assist their
Qualifiers" section below.
projects in earning LEED points. For the purposes
of this study, these features or practices are not
Cost Estimate Qualifiers
considered part of the LEED premium.
Conversely, in a few cases, GSA's policies and
practices limit the applicability of LEED credits
The cost impacts derived in the study are subject to
that might be more easily included in non-GSA
a number of qualifiers, which are important in
projects. Some of the most significant GSA-specific
understanding how the costs may relate to other
criteria are listed as follows:
building types, building sizes, and non-GSA
projects. Key qualifiers are reviewed as follows:
building commissioning process for its projects
1. Building Program and Site Assumptions
and therefore does not consider it to be a
The specific programmatic requirements of the
LEED cost. For the purposes of this study,
Courthouse and Office Building play an important
GSA's commissioning efforts are assumed to
role in determining the applicable LEED credits
earn both the LEED commissioning
and the resulting LEED cost impacts. Significantly
prerequisite and credit EA-3, Additional
different building types (e.g., laboratories, schools,
Commissioning.
and residential buildings) would likely develop a
Energy efficiency. GSA sets energy performance
different overall profile of LEED credits, and might
targets for their buildings, which are typically
use significantly different approaches to achieve
more stringent than local energy codes or the
common credits.
ASHRAE standard 90.1-1999, which is used as
the baseline in LEED. For the Courthouse, a
The programmatic differences between new
target of 45,000 to 50,000 BTU/GSF/year was
construction (Courthouse) and renovation (Office
set, which translated to 1 LEED point
Building) also factor into the credit selections and
(approximately a 17 percent improvement)
resulting costs. The program for the Office
under LEED credit EA-1. Similarly, the Office
Building, for example, does not include site
Building modernization started with an energy
renovation or roof replacement, based on typical
use target of 50,000 to 55,000 BTU/GSF/year,
GSA modernization scopes. This significantly limits
which translated to 2 LEED points
the number of LEED site credits available in the
(approximately a 14 percent improvement) in
Office Building model, as compared to the new
the minimal faade renovation case, and 3
construction Courthouse.
LEED points (approximately an 18 percent
The scenarios in the study are also subject to a
improvement) in the full faade renovation
number of specific site assumptions (e.g., urban
case.
locations, brownfield redevelopment, no above-
Underfloor air delivery system. For new
grade parking, large site acreage for the Courthouse
construction projects, GSA's P100 (2003)
based on security setbacks). As with the
encourages the use of underfloor air delivery
programmatic assumptions, these specific site
systems in appropriate applications. In the
characteristics determine the feasibility of a number
Courthouse model of this study, an underfloor
of the LEED credits. Buildings in suburban or rural
air system has been included in the base costs.
settings, for instance, would develop a different
The system allowed the building to earn credit
profile of credits in the Sustainable Sites category,
EQ-2 (Ventilation Effectiveness) and assisted
which would result in different cost impacts in
in earning credit EQ-6.2 (Increased Occupant
those areas.
Control).
2. GSA-Specific Design Requirements
Dedicated ventilation system. GSA's P100 (2003)
requires dedicated outside air ventilation units
In addition to the general programmatic and site
for both perimeter and interior spaces. This
issues discussed above, GSA's comprehensive
design approach is used to provide greater
design criteria differentiate their projects from
GSA LEED COST STUDY
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