Use a ducted overhead variable air volume (VAV) air
5.5 Alternatives Components
distribution system with fan-powered VAV terminals with
for the HVAC Baseline System
hot water heating coils for cooling and heating, or
Use an underfloor VAV air distribution (UFAD/VAV) system
designed in accordance with the RF/UFAD Guidelines for
Life Cycle Costing of Alternatives
cooling, supplemented with two-pipe, above floor
A life cycle cost analysis shall be performed to determine
Use a standard, floor mounted four-pipe fan coil unit
the applicability and economic justification of the
system for heating and cooling for perimeter zones.
following alternatives for each project.
Interior zones must be served by one of the previous three
Life cycle cost analysis shall comply with requirements
VAV system options. Ceiling mounted fan coil units are not
addressed in Chapter 1, General Requirements. This
permitted.
includes consideration of analysis period, escalation
Electric heating coils shall be permitted only for nominal
discount rates, and other parameters. The indicated
heating requirements. Requests for use of electric heating
software program, "Buildings Life Cycle Cost", is
coils must be submitted directly to, and subsequently
recommended when used with provisions that support
authorized by, the GSA. No reheat is permitted.
"Federal Analysis-Projects Subpart to OMB A-94
Guidelines."
The building energy analysis shall be used to predict the
energy cost impact of each of the alternative outdoor air
distribution methods and components, as compared to
the baseline HVAC system, and shall form the basis of the
life cycle cost analysis.
Alternative Outdoor Air Distribution Method Dedicated
Perimeter Pressurization System. For projects where
a dedicated 100-percent outdoor air ventilation system,
sized to meet both the ventilation and pressurization
requirements of the building, is deemed to be infeasible
by GSA (supported by a life cycle cost analysis provided
by the A/E), the building shall have a dedicated perimeter
pressurization system sized to meet only the
pressurization requirements of the building. In these
cases, the ventilation requirements of the building shall
be provided by the floor-by-floor air-handling units. This
exception to the dedicated 100-percent outdoor air
ventilation system requirement is limited to special
applications or modernization projects where the DOAVS
approach is infeasible.
127
MECHANICAL
ENGINEERING
5.5
Alternatives Components for the HVAC Baseline System
Revised March 2005 PBS-P100
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