gsa findings ufad
TRANSCRIPT
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GSA FINDINGS ON PRESSURIZEDGSA FINDINGS ON PRESSURIZED
UNDERFLOOR AIR DISTRIBUTIONUNDERFLOOR AIR DISTRIBUTIONSYSTEMSSYSTEMS
Presented toPresented to
ASHRAE TC 5.3ASHRAE TC 5.3
30 January 200730 January 2007
ByBy
Vijay K. Gupta, P.E., Fellow ASHRAEVijay K. Gupta, P.E., Fellow ASHRAE
James E. Woods, Ph.D., P.E., Fellow ASHRAEJames E. Woods, Ph.D., P.E., Fellow ASHRAE
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Inventory of GSA Facilities with UFADInventory of GSA Facilities with UFAD
~10 M GSF in inventory
5 M in operations3 M in construction
2 M in design
9 Projects (~ 3 M GSF) werechanged during design from
UFAD to CAD
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History and Status of GSA UFADHistory and Status of GSA UFAD
Draft Guideline and StandardDraft Guideline and Standard 2003:
PBS P100-2003 required RAF and encouraged installation of UFAD
2003-2005: Conducted HVAC Quality Assurance Reviews of UFADdesigns for GSA facilities
2004: GSA contracted NIBS to develop UFAD Design Guide
2005: PBS P100-2005 did not encourage use of UFAD, however
UFAD Guideline, drafted by NIBS as supplement for PBS P100-2005,was required by GSA for design
May: GSA convened Roundtable to discuss UFAD systems
2006: July: Expert Panel convened by NIBS
February December: Plenum Air Leakage Tests on six facilities September: Final draft of Standard prepared by NIBS
December: GSA decided not to publish the draft Standard
2007:
PBS P100 (to be published in 2007) will not permit UFAD
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Plenum Air LeakagePlenum Air Leakage
Results of Air
Leakage testsshowed plenum
leakage rates of 30
200% of designairflow rates at
plenum static
pressures of 0.07 in.w.g. (17 Pa)
View of Library in FCH-1 withdiffusers taped for testing
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Methods of Air Leakage TestingMethods of Air Leakage Testing
Prior to Substantial CompletionPrior to Substantial Completion
After Substantial CompletionAfter Substantial Completion
Smoke Test to locate air leakage
pathways
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Prior to Substantial CompletionPrior to Substantial Completion
4,000 15,000 ft2
areas Determine Cat 1 and
2 air leakage rates atdesign s.p.
Use separate fan
Establish steady- state s.p. beforeobtaining data
Calibrated
fan (FCH-2)
One of four
SamplingLocations (FCH-2)
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Substantial Completion TestsSubstantial Completion Tests
AHU Zone up to
25,000 ft2
Determine Category 1
and 2 leakage rates
Use actual AHU with
VFD at design s.p.
Establish steady-state
s.p. before obtaining
data
One of several
Thermostatic zones
Served by AHU(FCH-1)
Typical AHU
With VFD and
Coil bypass for
UFAD (FCH-1)
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Smoke TestsSmoke Tests
Purpose: to locate
air leakagepathways
Use theatrical smoke
generator (non-toxic)
Theatrical smoke generator
(FCH-2)
Smoke induced into calibrated
fan inlet (FCH-2)
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Cat 1 Air Leakage (FCHCat 1 Air Leakage (FCH--2)2)
First Mockup (22-24 Feb 06): 70% Air Leakage in Init ial
Tests
35% after first mitigation
16% after second mitigation
Second Mockup (subsequentdate): 35% Air Leakage in Init ial
Tests
We have not received furtherinformation
Smoke from
shelf after repair Smoke from
outlet box in confroom
Smoke from plumbing access
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Category 1 and 2 Air Leakage (FCHCategory 1 and 2 Air Leakage (FCH--1)1)
First Series of Tests (Oct-Dec 05): Initial range of Cat 1+2 air leakage
rates was 34% (AHU 6 4th floor) to68% (AHU 5 3rd floor)
After remediation, range was 26%
(AHU 1 - 1st
floor) to 59% (AHU 7 4th floor)
Second Series of Tests (May 06):
AHUs 2 and 3 Second Floor
Cat 1+2 was 43% of design airflowrate at 0.07 in. wg
Cat 1 was 32% of design airflow rateat 0.07 in. wg.
Sealed pipe and cable
penetrations throughRAF
Taped floor diffuser on carpet
Column and piping
penetrations throughRAF
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Summary of Air Leakage Findings*Summary of Air Leakage Findings*
Type of
Facility
Dates of
Tests
Cat 1 Cat 2 Cat 1+2
FB-1 7-06
52 8 60FB-2 7-06 43 2 45
FB 3 8-06 40-200 NA NA
FB-4 11-06 44-48 NA NA
FCH-1 11-05 to
9-06
NA
32
NA
11
34-68
43
FCH-2 11-05 to
5-06
70-16
35
NA
NA
NA
NA*Percentage of design airflow rate at 0.07 in. w.g.
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GSA Air Leakage Criteria for UFADGSA Air Leakage Criteria for UFAD
Plenums at design static pressure (e.g.,Plenums at design static pressure (e.g.,0.07 in. wg or 17.5 Pa)0.07 in. wg or 17.5 Pa)
TestTest Air LeakageAir Leakage(Category 1 + 2)(Category 1 + 2) Category 1Category 1
MockupMockup 0.1 cfm/ft0.1 cfm/ft22
floor areafloor area
0.03 cfm/ft0.03 cfm/ft22
floor areafloor area
BuildingBuilding
FloorFloor
PlenumsPlenums
0.1 cfm/ft0.1 cfm/ft22
floor areafloor area
oror
10% of design supply10% of design supply
airflow rate, whicheverairflow rate, whichever
value is smallervalue is smaller
0.03 cfm/ft0.03 cfm/ft22
floor areafloor area
oror
3% of design supply3% of design supply
airflow rate, whicheverairflow rate, whichever
value is smallervalue is smaller
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Conclusions (1)Conclusions (1)
Air leakage consequences are significant:Air leakage is an architectural design and general construction Issue.
Construction of an airtight plenum requires strict coordination of ten totwelve trades, and special construction techniques that have not been
developedConcrete
Masonry
Drywall
Millwork Sealant and joint specialists
Carpenters
Sheet Metal
Plumbing
Electrical
Communications
Etc.
Predictions of air leakage are unreliable: testing is required at this time.
Air leakage testing results indicate GSA goal has not been met.
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Conclusions (2)Conclusions (2)
Thermal mass of slab is a major issue forenergy and control
Heat and moisturetransmission/condensation in the plenumis also a major issue
Life safety codes need to address UFADsystems
Drainage of water from piping leaks or firesprinkler discharge is a major issue
Access to underfloor equipment is difficultat best
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Conclusions (3)Conclusions (3)
Integrated design is essential between
architects, engineers
Testing procedures must be developed by
coordinated effort among building code
officials, and Standards writingorganizations, such as ASTM, ASHRAE,
NFPA, ASCE, IEEE, UL, SMACNA, ETC.