Effects of Temperature and Air Infiltration and on Thermal ... SPFA-ATI... · Effects of...

Effects of Temperature and Air Infiltration and on Effects of Temperature and Air Infiltration and on Thermal Performance of Insulation and InsulatedThermal Performance of Insulation and InsulatedEffects of Temperature and Air Infiltration and on Effects of Temperature and Air Infiltration and on Thermal Performance of Insulation and InsulatedThermal Performance of Insulation and InsulatedThermal Performance of Insulation and Insulated Thermal Performance of Insulation and Insulated

Frame Wall AssembliesFrame Wall AssembliesThermal Performance of Insulation and Insulated Thermal Performance of Insulation and Insulated

Frame Wall AssembliesFrame Wall Assemblies

ROGER MORRISON, P.E., RRCRICHARD S. DUNCAN, Ph.D., P.E.

With funding fromWith funding from…

NOTICE: All statements, information and data given herein are believed to be accurate and reliable, but are presented without guarantee, warranty or responsibility of any kind, express or implied Statements or suggestions concerning possible use of products are made without representation or warranty that any such use is free of patent infringement and

March 16-17, Hilton Torrey Pines, San Diego, CA

express or implied. Statements or suggestions concerning possible use of products are made without representation or warranty that any such use is free of patent infringement, and are not recommendations to infringe any patent. The user should not assume that all safety measures are indicated herein, or that other measures may not be required. The values presented herein are typical values and are not to be interpreted as product specifications. User assumes all liability for use of the information and results obtained.

OVERVIEWOVERVIEW

• BACKGROUND– Physics of Heat Transfer– Material Thermal Performance– Building Envelope System Thermal Performance

• TEST METHODSystem Thermal Performance– System Thermal Performance

– Guarded Hot Box Apparatus– Wall Specimens

• TEST RESULTSTEST RESULTS– Data Table– Effects of Air Leakage– Effects of Exterior Temperature

• CONCLUSIONS • NEXT STEPS• ACKNOWLEDGEMENTS


BACKGROUND: Physics of Heat TransferBACKGROUND: Physics of Heat Transfer

• Conduction: through a solid material

)( coldhot TTt

kAQ −=




)( coldhot TTt

kAQ −=

)( coldhot TThAQ −=• Convection: movement of gas or liquid

)( coldhotp TTmcQ −=




)( coldhot TTt

kAQ −=


)( coldhotp TTmcQ −=

• Radiation: transmission of light waves)( 44

coldhot TTcQ −= σ




)()( coldhotcoldhot TTRATT

tkAQ −=−=


R value or thermal )( coldhotp TTmcQ −=R-value or thermal resistance, is a material’s ability to resist heat flow

• Radiation: transmission of light waves)( 44

coldhot TTcQ −= σ

resist heat flow


BACKGROUND: Material Thermal PerformanceBACKGROUND: Material Thermal Performance

• R-value laboratory measurement y– Guarded hot plate (ASTM C177)– Heat flow meter (ASTM C518)

)()( ldhldh TTATTkAQ −=−=Thot

Tcold

Q

• Both methods minimize heat flow by convection and radiation

)()( coldhotcoldhot TTR

TTt

Q

by convection and radiation

• Performed at prescribed mean temperature and temperature differencedifference

– Mean = ½(Thot+Tcold), usually 75ºF– Range = Thot - Tcold, usually 40ºF

Source: LaserComp Inc (www lasercomp com)


Source: LaserComp, Inc. (www.lasercomp.com)

BACKGROUND: Material Thermal PerformanceBACKGROUND: Material Thermal Performance

Current Thermal Testing Standards


Bogdan, M. and Tucker, R.T. 2007 Center for the Polyurethanes – UTECH Conference Proceedings

BACKGROUND: BACKGROUND: Building Thermal PerformanceBuilding Thermal Performance

• Real construction practices result in defects in the building envelope

Cracks

Gaps

Holes




• Improper material installation

Compression

will compound the effects of these defects

Inset Stapling




• Improper material installation

Compression

will compound the effects of these defects

Inset Stapling

Air Leakage + Improper Installation = Underperformance



• Components of the building envelope (wall), including insulation, can transfer heat via all three modes

• Most accurate solution: in-situ energy measurements over 1+ years

• Whole-house solution is expensive

Source: ENERGY STAR


TEST METHOD: System Thermal PerformanceTEST METHOD: System Thermal Performance

• Laboratory measurement of wall section is a suitable compromise– Guarded hot box (ASTM C1363)

)()( coldhotw

coldhotw TTRATTAUQw −=−=

• Real wall section = system of components

• All three modes of heat transfer• All three modes of heat transfer • Environmental effects

– perforations/defects– air leakage Source: Architectural Testing– air leakage– fenestration– moisture movement– wall orientation

Source: Architectural Testing, Inc. (www.archtest.com)


TEST METHOD: Guarded Hot Box ApparatusTEST METHOD: Guarded Hot Box ApparatusThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.


TEST METHOD: Guarded Hot Box ApparatusTEST METHOD: Guarded Hot Box Apparatus

WARM ROOM

GUARD ROOMCOLD ROOM

METERING

Tcold

WAL

L S

PEC

IMEN Exhaust Fan

FAN

CHAMBER

FlowMeter

ThotT

Q

CHILLERhotTw-hotTw-cold

)()( coldwhotwcoldwhotww TTRATTAUQ −−−− −=−=

Pressure Measurement

100* ×= w

RR

WPI Wall Performance Indexcoldwhotww

coldwhotww R

Q measured by metering chamber

Tw-hot, Tw-cold measured by thermocouples

wR

Rw, determined experimentally

R*w expected wall R-value, calculated


Uw, Rw calculated above from measured material R-values

TEST METHOD: Wall SpecimensTEST METHOD: Wall Specimens

97 5in

How are the leakage ports sized?97.5in.

16.0in. 16.0in. 16.0in. 16.0in. 16.0in. 16.0in.

p

0.5" paper-facedgypsum board

0.5" oriented strandboard (OSB)

96.0

in.

93.0

in.

board (OSB)sheathing or PIR

insulated sheathing

0 125" dia0.125 dia.intentional

leakage portsthrough OSBsheathing only

(49 total)


TEST METHOD: Wall SpecimensTEST METHOD: Wall Specimens

22

13 14 15 16 17 18

7 8 9 10 11 1220 21

1 2 3 4 5 6

19


19

TEST RESULTS: Experimental DataTEST RESULTS: Experimental Data

Four wall constructions: All 2”x4” 16oc Three with OSB one with R3 PIRFour wall constructions: All 2 x4 -16oc. Three with OSB, one with R3 PIR sheathing

Three cavity insulations: R13 kraft-faced fiberglass, open-cell SPF, closed-cell SPF



Nominal R value of cavity insulations based on label or extrapolationNominal R-value of cavity insulations based on label or extrapolation.

Open cell sprayed at ~3.25” to minimize waste, less than R13

Closed-cell sprayed at 1.5”, intentionally not R13 to show equivalent performance



Real exterior conditions avg temp not 75F free convection leakage induced:Real exterior conditions – avg. temp. not 75F, free convection, leakage induced:1. Cold exterior(25ºF), no wind2. Cold exterior (25ºF), simulated 15 mph wind3. Extreme cold exterior (-15ºF), simulated 15 mph wind

How is the pressure difference determined?


4. Extreme hot exterior (115ºF), simulated 15 mph winddifference determined?


Assembly air leakage measured under applied pressure difference (ASTM E283)Assembly air leakage measured under applied pressure difference (ASTM E283)



Rw: measured R value for the wallRw: measured R-value for the wallR*w: calculated R-value for the wall component properties (isothermal planes)WPI: Wall Performance Index = (Rw / R*w) x 100


TEST RESULTS: Air Leakage Effect @ 25ºFTEST RESULTS: Air Leakage Effect @ 25ºF

150

Key Observations…

100

125

dex

No Wind

15 mph Wind

75

Perf

orm

ance

Ind

25

50

Wal

l

0A: Fiberglass

BattsB: Open-Cell

SPFC: Closed-Cell

SPFD: Closed-Cell

SPF + PIR

Wall : Cavity Insulation



150

Key Observations…

• Without forced air leakage,

100

125

dex

No Wind

15 mph Wind

g ,fiberglass and closed-cell insulations appear to perform at or above expected performance

75

Perf

orm

ance

Ind

25

50

Wal

l

0A: Fiberglass

BattsB: Open-Cell

SPFC: Closed-Cell

SPFD: Closed-Cell

SPF + PIR




150

Key Observations…


100

125

dex

No Wind

15 mph Wind


75

Perf

orm

ance

Ind

• Open-cell SPF is slightly below expected performance without wind due to extrapolation error

25

50

Wal

l

0A: Fiberglass

BattsB: Open-Cell

SPFC: Closed-Cell

SPFD: Closed-Cell

SPF + PIR




150

Key Observations…


100

125

dex

No Wind

15 mph Wind


75

Perf

orm

ance

Ind


25

50

Wal

l

• Presence of air leakage from a 15 mph wind significantly reduces thermal performance of fiberglass walls

0A: Fiberglass

BattsB: Open-Cell

SPFC: Closed-Cell

SPFD: Closed-Cell

SPF + PIR


walls.



150

Key Observations…


100

125

dex

No Wind

15 mph Wind


75

Perf

orm

ance

Ind


25

50

Wal

l

• Presence of air leakage from a 15 mph wind significantly reduces thermal performance of fiberglass walls

0A: Fiberglass

BattsB: Open-Cell

SPFC: Closed-Cell

SPFD: Closed-Cell

SPF + PIR


walls.

• Much less reduction in performance observed for spray foam walls


TEST RESULTS: Air Leakage vs. Ext. Temp.TEST RESULTS: Air Leakage vs. Ext. Temp.

3.00A Fib l B tt

Key Observations…

2 00

2.50

FM)

A: Fiberglass BattsB: Open-Cell SPFC: Closed-Cell SPFD: Closed-cell SPF + PIR

1.50

2.00

akag

e R

ate

(CF

0.50

1.00

Air

Le

0.00-50 0 50 100 150

Exterior Temperature (deg F)



3.00A Fib l B tt

Key Observations…

• The most air-permeable cavity

2 00

2.50

FM)


The most air permeable cavity insulation is fiberglass

1.50

2.00

akag

e R

ate

(CF

0.50

1.00

Air

Le

0.00-50 0 50 100 150




3.00A Fib l B tt

Key Observations…


2 00

2.50

FM)



• Walls using spray foam have significantly less air leakage

1.50

2.00

akag

e R

ate

(CF significantly less air leakage

0.50

1.00

Air

Le

0.00-50 0 50 100 150




3.00A Fib l B tt

Key Observations…


2 00

2.50

FM)




1.50

2.00

akag

e R

ate


• Closed-cell spray foam has the lowest leakage rate, about 10% that of fiberglass

0.50

1.00

Air

Le

g

0.00-50 0 50 100 150




3.00A Fib l B tt

Key Observations…


2 00

2.50

FM)




1.50

2.00

akag

e R

ate


• Closed-cell spray foam has the lowest leakage rate, about 10% that of fiberglass

0.50

1.00

Air

Le

g

• Extreme hot/cold temperatures appear to increase leakage in fiberglass and ccSPF-polyiso walls.

0.00-50 0 50 100 150


g p y


TEST RESULTS: WPI vs. Air Leakage RateTEST RESULTS: WPI vs. Air Leakage Rate

150Key Observations…

• As air leakage increases, thermal

100

125

e In

dex

g ,performance of all walls decrease

50

75

Wal

l Per

form

ance

0

25

W


0.0 0.5 1.0 1.5 2.0 2.5

Air leakage rate (CFM)





100

125

e In

dex


• Effects of air leakage most significant in fiberglass walls

50

75

Wal

l Per

form

ance

g

0

25

W


0.0 0.5 1.0 1.5 2.0 2.5






100

125

e In

dex



50

75

Wal

l Per

form

ance

g

• Unexpected high leakage and lower performance observed for closed-cell SPF applied to polyiso board.

0

25

W


0.0 0.5 1.0 1.5 2.0 2.5






100

125

e In

dex



50

75

Wal

l Per

form

ance

g

• Unexpected high leakage and lower performance observed for closed-cell SPF applied to polyiso board.

0

25

W


• Possible delamination or thermal shrinkage at extreme temperatures ?

0.0 0.5 1.0 1.5 2.0 2.5



TEST RESULTS: WPI vs. Exterior TemperatureTEST RESULTS: WPI vs. Exterior Temperature

150

Key Observations…

100

125

dex

75

100

Perf

orm

ance

Ind

25

50

Wal

l


0-50 0 50 100 150

Exterior Temperature, (F)



150

Key Observations…

• In presence of 15 mph simulated

100

125

dex

p pwind, fiberglass wall performs at about 82% of rated performance, decreasing down to 72% at high outdoor temperatures

75

100

Perf

orm

ance

Ind outdoor temperatures.

25

50

Wal

l


0-50 0 50 100 150




150

Key Observations…


100

125

dex


75

100

Perf

orm

ance


• Closed-cell SPF applied to OSB sheathing performs consistently better than expected at all

25

50

Wal

l


better than expected at all temperatures.

0-50 0 50 100 150




150

Key Observations…


100

125

dex


75

100

Perf

orm

ance


• Closed-cell SPF applied to OSB sheathing performs consistently better than expected at all

25

50

Wal

l


better than expected at all temperatures

• Cannot separate effects of mean temperature on material thermal

0-50 0 50 100 150


temperature on material thermal conductivity (R-value) from effects of air leakage


CONCLUSIONS CONCLUSIONS

• Fiberglass and ccSPF walls perform as expected without wind load, while ocSPF wall performs slightly below expectations, possibly due to extrapolated R valueto extrapolated R-value.

• SPF insulated walls exhibit nearly 10 times less air leakage than walls insulated with fiberglass insulation under a 15 mph simulated wind loadload.

• Thermal performance of all SPF walls not significantly affected by wind compared to fiberglass insulated walls

• Extreme exterior temperatures increase air leakage and decrease thermal performance of all walls, possibly due to mismatched thermal expansion.

• Although it is known that insulation thermal conductivity is dependent on mean test temperature, it was not possible to delineate effects of air leakage and temperature-dependent thermal conductivities on the performance of the wall.


performance of the wall.

NEXT STEPSNEXT STEPS

• More test data is needed. Data from this study are based on single specimen of each wall type.

• Testing at extreme temperatures, with and without a simulated wind load, is needed to delineate of air leakage and mean temperature effects on wall thermal performance.

• Need to determine if cracking, shrinkage or delamination occurs at extreme temperatures – durability of air barrier materials and systems are important.

• Thermal performance of walls is dependent on air leakage. Insulations installed to the same R-value with and without integral air barriers can perform differently under wind/pressure loads.


ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

The authors of this paper would like to thank the Spray Polyurethane Foam Alliance and American Chemistry Council - Center for the Polyurethanes Industry for their management and support of thisPolyurethanes Industry for their management and support of this important research project.

Also, we would like to thank Craig Drumheller of NAHB and Mike Toman of Architectural Testing Inc for their technical insightToman of Architectural Testing, Inc. for their technical insight regarding the guarded hot box test procedure.


QUESTIONS?QUESTIONS?


APPENDIXAPPENDIX

14R 3 25/in

R 13 Open-Cell SPF R-value i h d ith

10

12R 3.25/in per inch decreases with

thickness

6

8

R-v

alue

R 3.39/in

2" x 4" (3

2

4R 3.83/in

3.5" thick)

00 1 2 3 4 5

thi k t


thickness, t

APPENDIXAPPENDIX

Open-cell insulation was ‘short-filled’ to an average thickness of 3 25”


thickness of 3.25

APPENDIXAPPENDIX

Effective Air Leakage (orifice) Area

D

rrL C

PKQA

Δ=

2:

ρ

whereAL = effective air leakage area, in2

Qr = air flow rate, 4.8 cfmρ = air density, 0.075 lbm/ft3

ΔPr = reference pressure difference, 0.3 in of water columnCD = discharge coefficient (assumed to be 0.6)D g ( )K = unit conversion factor = 0.186


APPENDIXAPPENDIX

Equivalent Wind Velocity Pressure

c

av cg

Up

2

2ρ=

wherepv = wind velocity pressure on the wall (inches of water)Qr = air flow rate, 4.8 cfmρ = air density in cold room, lbm/ft3ρa air density in cold room, lbm/ftU = wind velocitygc = gravitational constant, (32.2 ft/s2)c= unit conversion factor = 0.414


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