Gsa Findings Ufad

8/13/2019 Gsa Findings Ufad

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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


BuildingBuilding

FloorFloor

PlenumsPlenums



oror

10% of design supply10% of design supply

airflow rate, whicheverairflow rate, whichever

value is smallervalue is smaller



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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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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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.

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