Characterization of the hygrothermal performance of wall systems

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A version of this document is published in / Une version de ce document se trouve dans: ASHRAE Seminar 29 – Moisture Management Concerns in Commercial and Residential Buildings, New York, USA, Jan. 21, 2008, pp. 1-83

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Characterization of the Hygrothermal

Performance of Wall Systems

W. Maref, M. Manning , M. Rousseau & W. Lei

ASHRAE Seminar 29- Moisture Management Concerns in Commercial

and Residential Buildings, New York, USA, January 21, 2008

(4)

Slide 2

Team

K. Abdulghani

W. Lei

M. Ma

nning

W

. Ma

ref

M. Nic

h

olls

T. Aubin

M

. Rousseau

R. Berzins

(5)

Slide 3

Outline

• Background

• Field Exposure of Wall Facility (FEWF)-BES

• Results and Discussion

• Summary

• Future Work

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Slide 4

Ventilation and Wall Research House Facility

2. FIELD EXPOSURE

OF WALL FACILITY –

(FEWF) BES

Study & compare traditional & innovative BE strategies

1. VENTILATION,

HEATING AND

COOLING FACILITY

- IE

Study & compare

traditional & innovative ventilation, heating & cooling strategies

(7)

Slide 5

Field Exposure of Wall

Facility (FEWF)

Objectives

– Compare performance of different side-by-side wall assemblies

– improve understanding of HAM response of wall and window

assemblies exposed to naturally occurring climate loads of Ottawa as

well as to indoor environment loads of T, RH and P defined by

occupancy and HVAC systems.

– Research the interaction between the building envelope and the

indoor environment

– Complement IRC’s controlled laboratory test and modeling

simulations

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Slide 6

Field Exposure of Wall

Facility (FEWF)

• Experimental Approach

–

Year 1 (2006-2007) Commissioned the facility by monitoring

three identical test specimens of traditional construction

(2x6) through Fall, Winter and Spring.

–

Year 2 (2007-2008) Examine the effect of exterior insulation

retrofit on the hygrothermal response of wood-frame walls.

This project is jointly funded with CMHC and NRCan

–

Year 3 and beyond Expand the program in collaboration

with Indoor Environment to examine whole house

performance issues.

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Slide 7 South facade Instr ed w Instrument ed window Instrumented window Test frame designed to provide the largest possible free bay for placement of several test specimens Max. 19 ft available Stack casing location North facade West facade

(10)

Slide 8

Field Exposure of Walls

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Slide 10 DETEC_9 DETEC_11 T_10 T_8 16.0 T_9 RHT_7 DETEC_14 DETEC_13 DETEC_12 MP_1 2.0 DETEC_10 T_7 _{RHT_6} 15.0 2.0 20.0 17.0 3.0

LAYER 4 - Interior Face of OSB

HF_1 (W2 only) JW_3 DETEC Thermistor Heat Flux Moisture Pin Wireless Relative Humidity

(13)

Slide 11 14.0 7.0 DETEC _17 DETEC _16 MP_3

LAYER 5 - Stud Cavity

DET EC_15 MP _2 HF_2 _(W2 on ly ) Moisture Pin

(14)

(15)

Slide 13 RHT_9 15.0 T_13 T_14 17.0 T_11 RHT_8 T_12

LAYER 6 - Interior Face of Insulation & Stud Cavity (Exterior side of Vapour Barrier)

P_3 (Low Pressure) 7.3 10.0 HF_3 (W2 only) JW_4 Delta Pressure

(16)

Slide 14

LAYER 7 - Interior Face of Drywall

17.0 15.0 T_18 T_17 RHT_10 (air) T_16 T_15 7.0 T_19 (W2 and W3 only) Thermocouple

(17)

Slide 15

W3

W2

(18)

(19)

(20)

Slide 18

Experimental Approach

• Challenging the wall experimental begins:

– Stage 1- Create air leakage path and monitor under

naturally occurring int. and ext. conditions on two of

three specimens (1 week)

(21)

Slide 19 D ryw a ll

W1

W2

W3

(22)

Slide 20

Air Leakage

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Slide 21

• Challenging the wall experimental begins:

– Stage 1- Create air leakage path and monitor under

naturally occurring int. and ext. conditions on two of

three specimens (1 week)

– Stage 2- Increase indoor RH to 70% and induce 5

Pa positive pressure while air leak is present in two

specimens, for a certain period of time

(24)

Slide 22 D ryw a ll

W1

W2

W3

(25)

Slide 23

Conditioning Chamber

on the Room Side

W1

W2

(26)

Slide 24 Wall specimen EXT. INT. Conditioning chamber Moisture-laden air exfiltration

(27)

Slide 25

• Challenging the wall experimental begins:

– Stage 1- Create air leakage path and monitor under

naturally occurring int. and ext. conditions on two of

three specimens (1 week)

– Stage 2- Increase indoor RH to 70% and induce 5

Pa positive pressure while air leak is present in two

specimens, for a certain period of time

– Stage 3- Return to naturally occurring conditions to

monitor drying. Disassemble the indoor chamber

(28)

Slide 26

(29)

Slide 27

FEWF Chamber RH%, Pressure Vs Time

-10 0 10 20 30 40 50 60 70 80 28 -J an-07 4-F eb -07 11 -F eb -07 18-F eb-07 25-F eb-07 4-M ar -07 11 -M ar -07 18-M ar -0 7 25 -M ar -07 1-A pr -0 7 8-A pr -0 7 15-A pr -0 7 2 2-A pr-0 7

Date and Time

RH (% ), P (P a ) RH, % Pressure, Pa W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W5 W W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 6 mm opening 3 mm opening Incomplete data

(30)

Slide 28

Date and Time

RH (% ), P (P a ) RH, % Pressure, Pa W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W5 W W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 6 mm opening 3 mm opening Incomplete data Condition A • 0 Pa pressure • 70% RH • No opening

(31)

Slide 29

Date and Time

RH (% ), P (P a ) RH, % Pressure, Pa W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W5 W W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 6 mm opening 3 mm opening Incomplete data Condition B • 5 Pa pressure • 50% RH • 6 mm opening

(32)

Slide 30

Date and Time

RH (% ), P (P a ) RH, % Pressure, Pa W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W5 W W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 6 mm opening 3 mm opening Incomplete data Condition C • 5 Pa pressure • 30% RH • 3 mm opening

(33)

Slide 31

Date and Time

RH (% ), P (P a ) RH, % Pressure, Pa W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W5 W W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 6 mm opening 3 mm opening Incomplete data Condition D • 0 Pa pressure • 50% RH • 3 mm opening

(34)

Slide 32

(35)

Slide 33

Diagram for Moisture

Detection Tape Locations

on the interior of the OSB

(36)

Slide 34

Diagram for Moisture

Detection Tape Locations

in the Stud Cavity

(37)

Slide 35 Exterior Interior Vinyl Siding Sheathing Membrane OSB

Stud Cavity with Fiberglass Insulation

Vapour Barrier Drywall

Material

P1 P2 P3 P Chamber

Reference for all Pressure Sensors: Room Interior

Pressure Tap Locations

+ve pressure = pressure at the tap location is higher than the pressure in the room

(38)

Slide 36

Pressure, Wind speed and direction

-20 -10 0 10 20 30 40 50 60 22-F eb-07 23-F eb-07 24 -F eb -07 25 -F eb -07 26 -F eb -07 27 -F eb -07 28 -F eb -07 1-M a r-0 7 2-M a r-0 7 3-M a r-0 7 4-M a r-0 7 5-M a r-0 7 6-M ar -07 7-M ar -07

Date and Time

Pr e s su re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p ee d ( k m/ h) P1 - Pressure at Exterior P2 - Pressure behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

Wind speed data is from the Ottawa Airport

(39)

Slide 37

Date and Time

Pr e s su re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p ee d ( k m/ h) P1 - Pressure at Exterior P2 - Pressure behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind Wind from the West causes

(40)

Slide 38

Date and Time

Pr e s su re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p ee d ( k m/ h) P1 - Pressure at Exterior P2 - Pressure behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind Wind from the East causes

(41)

Slide 39

Date and Time

Pr e s su re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p ee d ( k m/ h) P1 - Pressure at Exterior P2 - Pressure behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind When the chamber is

pressurized, the exfiltration condition is forced (chamber and stud cavity pressure is higher than exterior pressure)

(42)

Slide 40

Date and Time

Pr e s su re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p ee d ( k m/ h) P1 - Pressure at Exterior P2 - Pressure behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

When the chamber is

pressurized, the exfiltration condition is forced (chamber and stud cavity pressure is higher than exterior pressure)

Except when +ve pressures from North and West winds negate the effect.

(43)

Slide 41

Conditions

Condition Pressure RH Opening Week

A 0 Pa 70% None 7 B 5 Pa 50% 6 mm 3 days in week 8 (22 to 24 Feb) C 5 Pa ~30% 3 mm 2 days in week 11 (16 to 17 Mar) D 0 Pa 50% 3 mm 15

(44)

Slide 42 Moi s tur e C ont e n t W a ll 2 Int e ri or O S B 0% 5% 10 % 15 % 20 % 25 % 30 % 35 % 40 % 28-Jan-07 4-Feb-07 11-Feb-07 18-Feb-07 25-Feb-07 4-Mar-07 11-Mar-07 18-Mar-07 25-Mar-07 1-Apr-07 8-Apr-07 15-Apr-07 22-Apr-07 Da te a n d Ti m e Moisture Content (%) 20 9 M C 21 0 M C 21 1 M C 21 2 M C 21 3 M C 21 4 M C Sli t in O S B

(45)

Slide 43 Moi s tur e C ont e n t W a ll 2 Int e ri or O S B 0% 5% 10 % 15 % 20 % 25 % 30 % 35 % 40 % 28-Jan-07 4-Feb-07 11-Feb-07 18-Feb-07 25-Feb-07 4-Mar-07 11-Mar-07 18-Mar-07 25-Mar-07 1-Apr-07 8-Apr-07 15-Apr-07 22-Apr-07 Da te a n d Ti m e Moisture Content (%) 21 2 M C Slit in O S B

(46)

Slide 44 Mo is tu re C ont e nt W a ll 2 S tud C a v ity 0% 5% 10 % 15 % 20 % 25 % 30 % 35 % 40 % 28-Jan-07 4-Feb-07 11-Feb-07 18-Feb-07 25-Feb-07 4-Mar-07 11-Mar-07 18-Mar-07 25-Mar-07 1-Apr-07 8-Apr-07 15-Apr-07 22-Apr-07 Da te a n d T im e Moisture Content (%) 21 7M C

(47)

Slide 45 Interior / Intérieur Exterior / Extérieur 6 7 1 5 2 3 4 Layer

Plastic Air/Vapour Barrier Drywall

Vinyl Siding Sheathing Membrane

Stud Cavity with Fiberglass Insulation OSB

Material

Wall 2 Horizontal Cross Section

-10.7 67 63 -10.5 59 -9.1 81 -7.3 15 19.5 71 22.5 -9.4 -8.8 -3.3 -6.6 17.2 _17.6 20.2 20.9 Week 07 11-Feb-07

Condition A: 0 Pa, 70% RH, no opening

• Despite the high humidity on the interior of the room (71%), the humidity behind the air/vapour barrier is low, 15%

• The location with the highest RH is the interior of the OSB, at ~81% - still below dewpoint

T RH

T _Interior T

(48)

Slide 46 -15 -10 -5 0 5 10 15 20 25 0 2 4 6 8 1 0 1 2 1 4 T e m p er at u re ( °C ) W2 T W3 T

DewPoint of Room Air

vi ny l s idi ng WR B OS B st u d ca vi ty w ith fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• The dewpoint of room air is ~17°C, a condition met by temperatures partway through the insulation

• The interior of the wall remains dry due to being well sealed

(49)

Slide 47 0 2 4 6 8 10 12 14 0 2 4 6 8 1 0 1 2 14 H u m idit y R a ti o (g v /k g da ) W1 humidity ratio W2 humidity ratio W3 humidity ratio vi n y l s idi ng WRB OS B st u d ca vi ty wi th fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• A large drop in the moisture content of the air occurs across the vapour barrier

• Air moisture content on the exterior side of the vapour barrier is nearly identical to the reference wall – with no added

indoor humidity loads

(50)

Slide 48

-20 -10 0 10 20 30 40 50 60 11-F eb-07 12 -F eb-07 13 -F eb -07 14 -F eb-07 15 -F e b-07 16 -F eb-07 17-F eb-07 18 -F eb-07 19 -F e b-07

Date and Time

P ress ur e ( P a) -100 -80 -60 -40 -20 0 20 40 60 W in d sp ee d (k m /h ) P1 - Pressure atExterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

With no opening, the stud cavity pressure follows the exterior pressure closely

(51)

Slide 49

FEWF Wall 2 - Interior of OSB - Layer 4 - Liquid

0 20000 40000 60000 80000 100000 120000 2/10/07 0:00 2/11/07 0:00 2/12/07 0:00 2/13/07 0:00 2/14/07 0:00 2/15/07 0:00 2/16/07 0:00 2/17/07 0:00 2/18/07 0:00 2/19/07 0:00 Date and Time

R e si st an ce ( k ⎝ ) 209L 210L 211L 212L 213L 214L 11-Feb-07 Resistan c e (k Ω )

• The interior surface of the OSB remains dry at all moisture detection tape locations

(52)

Material

Wall 2 Horizontal Cross Section

-7.0 66 63 -6.5 62 -5.0 100 -3.2 30 20.4 49 23.0 -5.4 -5.2 -0.1 -2.1 18.4 18.7 21.0 21.3 7.42 6.67 7.22 Week 08 22-Feb-07 Interior Exterior

Condition B: 5 Pa, 50% RH, 6mm opening

• The interior of the room is at 49% RH, the humidity behind the air/vapour barrier is 30% RH – indicating that moisture is being introduced through the opening • The location with the highest RH is the interior of the OSB, at 100% - condensation would be expected

T RH

(53)

Slide 51 -10 -5 0 5 10 15 20 25 0 2 4 6 8 1 0 1 2 14 T em p era tu re ( °C ) W2 T W3 T

Dewpoint of Room Air

vi ny l s id ing WRB OSB st u d ca vit y w ith fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• The dewpoint of room air is ~12°C, a condition met by temperatures at the middle of the

insulation

• The opening in the vapour barrier allows moisture to enter the cavity, condensation is expected anywhere to the exterior of the insulation

(54)

Slide 52 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 1 0 1 2 14 H u m id ity R a ti o (g v /k g d a ) W1 humidity ratio W2 humidity ratio W3 humidity ratio vin y l s idi ng WRB OS B st u d ca vi ty wi th fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• The pressure and opening allow the high RH to enter the interior of the wall

• Air moisture content on the exterior side of the vapour barrier is higher than the reference wall – with no added indoor humidity loads

(55)

Slide 53

0 20000 40000 60000 80000 100000 120000 2/23/07 12:00 2/23/07 18:00 2/24/07 0:00 2/24/07 6:00 2/24/07 12:00 2/24/07 18:00 2/25/07 0:00

Date and Time

R e si st an ce ( k⎠ ) 209L 210L 211L 212L 213L 214L Resi stan ce (k Ω )

The interior surface of the OSB is wet, particularly at the base of the wall

Low resistance indicates the presence of liquid

Slit in OSB

Drying

Wetting

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Slide 54

-20 -10 0 10 20 30 40 50 60 23-Feb-07 12:00 23-Feb-07 18:00 24-Feb-07 0:00 24-Feb-07 6:00 24-Feb-07 12:00 24-Feb-07 18:00 25-Feb-07 0:00

Date and Time

Pr es s u re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s pe e d ( k m/h ) P1 - Pressure at_Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

For a large portion of the Condition B period, wind pressure balanced the applied 5 Pa chamber pressure.

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Slide 55

-20 -10 0 10 20 30 40 50 60 23-Feb-07 12:00 23-Feb-07 18:00 24-Feb-07 0:00 24-Feb-07 6:00 24-Feb-07 12:00 24-Feb-07 18:00 25-Feb-07 0:00

Date and Time

Pr es s u re ( P a ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s pe e d ( k m/h ) P1 - Pressure at_Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

In two instances, the exterior pressure dropped below the chamber pressure, allowing exfiltration, and corresponding to the wetting patterns

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Slide 56

Moisture Content - Wall 2 Interior OSB

0% 5% 10% 15% 20% 25% 30% 35% 40% 2/23/07 12:00 2/23/07 18:00 2/24/07 0:00 2/24/07 6:00 2/24/07 12:00 2/24/07 18:00 2/25/07 0:00

Date and Time

M o is tu re C o n te n t ( % ) 209MC 210MC 211MC 212MC 213MC 214MC

(59)

Slide 57

FEWF Wall 2 - Stud - Layer 5 - Liquid

0 20000 40000 60000 80000 100000 120000 2/23/07 12:00 2/23/07 18:00 2/24/07 0:00 2/24/07 6:00 2/24/07 12:00 2/24/07 18:00 2/25/07 0:00

Date and Time

R e si st anc e ( k¬ ) 215L 216L 217L Resi stan ce (k Ω )

Low resistance indicates the presence of liquid at the base of the stud cavity

(60)

Slide 58

Moisture Content - Wall 2 Stud Cavity

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 2/23/07 12:00 2/23/07 18:00 2/24/07 0:00 2/24/07 6:00 2/24/07 12:00 2/24/07 18:00 2/25/07 0:00

Date and Time

M o is tu re C o n te n t ( % ) 215L 216L 217L

(61)

Slide 59

Results

After

(62)

Slide 60

If

y

o

u

l

e

a

v

e

i

t

to

o

w

e

t

fo

r

to

o

l

o

n

g

,

th

e

n

…

.

(63)

Material

Wall 2 Horizontal Cross Section

-5.1 70 65 -4.3 67 -2.9 100 -0.9 29 20.8 27 23.0 -3.1 -3.0 1.5 0.3 18.8 19.3 21.2 21.4 6.91 6.20 6.72 Week 11 16-Mar-07

Condition C: 5 Pa, 30% RH, 3mm opening

• The interior of the room is at 27% RH, the humidity behind the air/vapour barrier is 29% RH – indicating that moisture is being introduced through the opening • The location with the highest RH is the interior of the OSB, at 100% - condensation would be expected

Interior Exterior

T RH

(64)

Slide 62 -10 -5 0 5 10 15 20 25 0 2 4 6 8 10 1 2 1 4 Te m p e ra tur e ( °C ) W2 T W3 T

vi ny l s id ing WR B OS B s tu d ca v ity w ith fib e rg la ss ai r / v a po ur b a rr ie r dr yw a ll

•The dewpoint of room air is ~4°C, a condition met by temperatures towards the outside of the

insulation

• The opening in the vapour barrier allows moisture to enter the cavity, condensation is expected at the OSB

(65)

Slide 63 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 1 0 1 2 14 H u m idit y R a ti o (g v /k g da ) W1 humidity ratio W2 humidity ratio W3 humidity ratio vin yl s idi ng WRB OS B st u d ca vi ty wi th fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• The pressure and opening allow the humidity to enter the interior of the wall

• Air moisture content on the exterior side of the vapour barrier is higher than the reference wall – with no added indoor humidity loads

(66)

Slide 64

-20 -10 0 10 20 30 40 50 60 16-Mar-07 0:00 16-Mar-07 6:00 16-Mar-07 12:00 16-Mar-07 18:00 17-Mar-07 0:00 17-Mar-07 6:00 17-Mar-07 12:00 17-Mar-07 18:00 18-Mar-07 0:00 Date and Time

Pr es su re (P a ) -100 -80 -60 -40 -20 0 20 40 60 Win d s p ee d (k m/ h) P1 - Pressure at Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

East winds for the majority of Condition C, kept exterior pressures low and allowed the Chamber and Stud Cavity Pressures to remain above the Exterior Pressure, creating an exfiltration condition

(67)

Slide 65

-20 -10 0 10 20 30 40 50 60 16-Mar-07 0:00 16-Mar-07 6:00 16-Mar-07 12:00 16-Mar-07 18:00 17-Mar-07 0:00 17-Mar-07 6:00 17-Mar-07 12:00 17-Mar-07 18:00 18-Mar-07 0:00 Date and Time

Pr es su re (P a ) -100 -80 -60 -40 -20 0 20 40 60 Win d s p ee d (k m/ h) P1 - Pressure at Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

A change in wind direction towards the end of Condition C brought exterior pressure conditions close to stud cavity and chamber pressure.

(68)

Slide 66

0 20000 40000 60000 80000 100000 120000 3/16/07 0:00 3/16/07 6:00 3/16/07 12:00 3/16/07 18:00 3/17/07 0:00 3/17/07 6:00 3/17/07 12:00 3/17/07 18:00 3/18/07 0:00

Date and Time

R e s ist an ce ( k฀ ) 209L 210L 211L 212L 213L 214L

The interior surface of the OSB is wet, particularly at the base of the wall

Resi stan ce (k Ω ) Slit in OSB

(69)

Slide 67

0 20000 40000 60000 80000 100000 120000 3/16/07 0:00 3/16/07 6:00 3/16/07 12:00 3/16/07 18:00 3/17/07 0:00 3/17/07 6:00 3/17/07 12:00 3/17/07 18:00 3/18/07 0:00

Date and Time

R e si st an c e ( k฀ ) 215L 216L 217L

Low resistance indicates the presence of liquid at the base of the stud cavity

Resi

stan

ce (k

Ω

(70)

Material

Wall 2 Horizontal Cross Section

2.6 75 69 2.8 67 3.5 76 4.6 27 21.0 50 23.0 3.0 3.3 6.5 4.6 19.3 19.4 21.3 21.5 5.15 4.59 5.08 Week 15 08-Apr-07

Condition D: 0 Pa, 50% RH, 3mm opening

• The interior of the room is at 50% RH, the humidity behind the air/vapour barrier is 27% RH

•The location with the highest RH is the interior of the OSB, at 76% (likely due to the lack of a pressure

driving force for exfiltration, and warmer exterior temperatures)

Interior Exterior

T RH

(71)

Slide 69 0 5 10 15 20 25 0 2 4 6 8 1 0 1 2 1 4 Te m p e ra tur e ( °C ) W2 T W3 T

vi n y l sid in g WRB OS B s tu d ca v ity w ith fib e rg la ss in su la ti on ai r / va po ur ba rr ier dr yw al l

•The dewpoint of room air is ~12°C, a condition met by temperatures at the middle of the insulation •Condensation is

expected at the OSB, however, measurements indicate that room air is not exfiltrating as much as in Conditions B and C

(72)

Slide 70 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 1 0 1 2 14 Hu mi d it y Rat io ( g v /k g d a ) W1 humidity ratio W2 humidity ratio W3 humidity ratio vin y l s idi ng WR B OS B st ud c a vity w ith fib e rg la ss ai r / va po ur ba rr ie r d ry wa ll

• While the air moisture content on the exterior side of the vapour barrier is higher than the

reference wall, the effect is not as pronounced as Conditions B and C – where interior pressure was applied

(73)

Slide 71

-20 -10 0 10 20 30 40 50 60

8-Apr-07 9-Apr-07 10-Apr-07 11-Apr-07 12-Apr-07 13-Apr-07 14-Apr-07 15-Apr-07 Date and Time

Pr es su re (Pa ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p e e d (k m/ h) P1 - Pressure at Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

West winds dominate at the

beginning and end of Condition D, creating conditions for infiltration

(74)

Slide 72

-20 -10 0 10 20 30 40 50 60

8-Apr-07 9-Apr-07 10-Apr-07 11-Apr-07 12-Apr-07 13-Apr-07 14-Apr-07 15-Apr-07 Date and Time

Pr es su re (Pa ) -100 -80 -60 -40 -20 0 20 40 60 Wi nd s p e e d (k m/ h) P1 - Pressure at Exterior P2 - Pressure Behind Cladding P3 - Pressure in Stud Cavity Chamber Pressure N wind E wind S wind W wind

East winds cause the exterior pressure to be below the interior pressure, resulting in exfiltration conditions

(75)

Slide 73

0 20000 40000 60000 80000 100000 120000 4/8/07 0:00 4/9/07 0:00 4/10/07 0:00 4/11/07 0:00 4/12/07 0:00 4/13/07 0:00 4/14/07 0:00 4/15/07 0:00

Date and Time

R e si st an ce ( k฀ ) 209L 210L 211L 212L 213L 214L

The interior surface of the OSB is dry at all

measured locations Resi stan ce (k Ω ) Slit in OSB

(76)

Slide 74

0 20000 40000 60000 80000 100000 120000 4/8/07 0:00 4/9/07 0:00 4/10/07 0:00 4/11/07 0:00 4/12/07 0:00 4/13/07 0:00 4/14/07 0:00 4/15/07 0:00

Date and Time

R e si st an c e ( k฀ ) 215L 216L 217L

Resi

stan

ce (k

Ω

)

The surface of the stud cavity is dry

(77)

Slide 75

SUMMARY

• We looked at risk of condensation due to exfiltration

(wetting) combined with infiltration (drying)

• Looked at the importance of wind speed and directions and

orientation of the envelope.

• Wind from West causes +ve pressures and infiltration • Wind from East causes –ve pressures and exfiltration

• When the chamber is pressurized the exfiltration cdt is forced (Chamber & Stud cavity pressure is higher than ext pressure) except when +ve from N & W winds negate the effect.

• If we have to look for long time period the exfiltration cdt, we

have to pressurized the chamber more than 35 Pa.

• Experimental results will be used to benchmark the HAM

(78)

Slide 76

Plans for this Winter and Spring

• Context:

– Focus on two energy retrofit scenarios for

exterior walls

• The question to investigate:

– What is the effect of the properties of thermal

insulation installed on the exterior of an existing

R20 wall on the wetting and drying potential of

that assembly, particularly when air leakage is

involved?

(79)

Slide 77

Adding thermal insulation on the exterior

of an insulated stud cavity wall can …

• Reduce thermal bridging at the framing

ᄕ

• Raise the temperature of that cavity, during cold

weather, resulting in lower potential for

condensation in stud cavity

ᄕ

• Reduce the drying potential to the exterior

ᄔ

• Promote mould growth in a wet cavity as the

cavity stays warmer over longer periods of the

(80)

Slide 78

What Happens Depends On:

• Vapour permeance and air permeance of added

insulation layer

• R value of the external layers in relation to the R

value of the internal layers

• Methods of installation for the insulation and siding

layers

• Air leakage rates & paths (deficiencies, gaps, cracks

unsealed openings in the assembly)

• Indoor conditions of RH, T and P

• Outdoor climate

• Other factors! e.g. rain penetration bypassing the 1

st

(81)

Slide 79

Exterior

Interior

R20 2X6 typical construction

Addition of a Low Air and Vapour Permeance

Insulation

Addition of a High Air and Vapour Permeance Insulation

& sheathing membrane

(82)

Slide 80

Interior

Detail B Detail A

Wall 1 Wall 2 Wall 3

Wall 1 –Noexterior insulation Wall 2 – Lower Air and Vapour

Permeance

Wall 3 –HigherAir and Vapour Permeance

•Vinyl Siding

•Sheathing Membrane (Tyvek) •OSB

•2x6 Stud Cavity with Fiberglass Insulation •Plastic Air/Vapour Barrier

•Drywall

•Vinyl Siding

•2 in. XPS Rigid Foam Insulation, 24 in. wide sections installed horizontally, butt joints taped

•Drywall

•Vinyl Siding

•Sheathing Membrane (Tyvek)

•¾ in. x 1½ in. Vertical Strapping @ 16 in. (400 mm) o.c. mounted on blocks, with 2.5 in. Mineral Fibre Insulation Batts installed horizontally

•Drywall

Plan View of the Test Specimens in Test Bay

Exterior

Interior

(83)

Slide 81

(84)

Slide 82

TH

A

N

K

Y

OU

(85)

Slide 83

http://irc.nrc-cnrc.gc.ca/bes/facilities/fieldex_e.html

Lab

-EEEF

Field

-FEWF

HAM

Model

-hygIRC 1D