Mould€growth€in€building€materials Experiments€&€Modelling · 5.7.2006 24.8.2006 13.10.2006 2.12.2006 21.1.2007 12.3.2007 1.5.2007 Kevytbetonimuovikuitu Kevytbetonilasivilla

Mould growth in building materialsMould growth in building materialsExperiments & ModellingExperiments & Modelling

Ruut Peuhkuri, VTTRuut Peuhkuri, VTT

TTY Laboratory of Structural Engineering, Tampere University of Technology, FinlandVTT Indoor Environment and Building Services, Technical Research Centre of Finland

In collaboration:

VTT TECHNICAL RESEARCH CENTRE OF FINLAND

2

A part of a research project

A MATHEMATICAL MODELING OF MOISTURE BEHAVIOUR ANDMOULD GROWTH IN BUILDING ENVELOPES

5/2005 –8/2008

Project team•TTY: Kati Salminen, Juha Vinha (project leader), Kimmo Lähdesmäki,

Tomi Strander•VTT: Hannu Viitanen, Tuomo Ojanen, Ruut Peuhkuri, Leena Paajanen,

Hanna Iitti, Liisa Seppänen•Industrial partners

We thank for the financing:•TEKES•VTT•Industrial partners


3

Outline

•Mould growth a normal phenomen in nature!•Quantification of mould growth•Existing models for predicting mould growth•Ongoing mould growth experiments in Finland

•experimental setups•present measurement results

•Simulation of field measurements•Use of models as design tool•Discussion points!


4

Ageing or biodeteriodation or damages

•During the service life of buildings, natural ageing ofmaterials due to different chemical, physical, andbiological processes can take place.

•Grey wood is a normal phenomenon in outside conditionson untreated wood (caused partly by discolouring fungi)

•In damage cases,more severe changesof material areassociated (mouldgrowth, decay, insectsplants, animals)


Mould and decay in buildings

•Level and duration ofmoisture stress connectedwith temperature are themost critical factors for thedurability of buildingmaterials and decay.

•Mould fungi, algae andlichens grow on the surfaceof many materials, e.g.textiles, leather, coatings,paper, wood, plastics,brickwork and concrete.


6

Loads on a building during the service life

humidity, temperature, material,time period, organisms

MOISTURE DAMAGEtolerances are overloaded

MOULD

RH: > 75 95 %Temp: 0 55 CTime: d, w, m

Moisture stress

DECAY

RH: > 90 95 %Temp: 5 50 CTime: w, m, y

Detection the damages and simulationthe causes of problems

Ageing

Indoor


7

Mouldindex 1 (start of growth)

Mould index 4 5 (plenty of growth)Mould index 6 (tight coverage)

Index for mould growth on materials, VTT model•0 = no growth•1 = some growth (microscopy)•2 = moderate growth (microscopy)

(coverage > 10 %)•3 = some growth (visually detected)•4 = visual coverage > 10 %•5 = coverage > 50 %•6 = tight coverage 100 %


Results on mould growth in static conditions(Viitanen and Ritschkoff 1991, Viitanen 1996)

0,700,750,800,850,900,951,00

0 2 4 6 8 10 12

Time (we e ks )

1 °C5 °C10 °C15 °C20 °C30 °C35 °C40 °C

time for initial s tage s of growth (inde x 1)


Critical factors for mould fungi (Hukka and Viitanen 1999)

75

80

85

90

95

100

10 0 10 20 30 40 50 60

Tem perature [°C]

RH[%]

Too dry

Too

cold

Too

hot

Growth

stop

t m =4 w eeks

t m =8 w eeks

Mould risk is high

Mould risk is possible

+−+−

=20> when%,80

20<= when,0.10013.3160.000267.0 23

TTTTT

RH crit

Factors:

Relative humidity

Temperature

Time

Substrate


10

Criticalconditionsfor mould

(weeks)

anddecay(months)

on pinesapwood

70

75

80

85

90

95

100

0 5 10 15 20 25 30Time (weeks)

RH

(%)

1 °C5 °C10 °C20 °C

70

75

80

85

90

95

100

0 4 8 12 16 20 24

Time (months)

RH

(%) 0 °C

5 °C10 °C20 °C


11

A mathematical model for simulation of growth of fungion wooden material (VTT model)

dMdt T RH W SQ

k k=⋅ − − + − +

17 0 68 13 9 0 14 0 33 66 02 1 2exp( . ln . ln . . . )

k

M

tt

Mv

m

1

1 12

11=

<

−>

,

,

when

when

.

[ ][ ]0,)(3.2exp1max max2 MMk +⋅−=

dMdt

t tt tt t

=− ≤

≤ − ≤

− >

0 0320

0 016

1

1

1

. ,,

. ,

when 6 h when 6 h 24 h

when 24 h

)02.6633.014.0ln9.13ln68.0exp( +−+−−= SQWRHTM

Delay of the growth

Retardation of the growthin the later stages

Growth at different stage

Regressionmodel on mouldgrowth basedon laboratorystudies

[Hukka and Viitanen 1999, Viitanen et al 2000]


12

Predicted mould growth at +5 and +30 °C in different constanthumidity conditions in pine sapwood

0

1

2

3

4

5

6

0 28 56 84 112 140 168Time (days)

Mou

ld in

dex

5 C RH 100 %

RH 97 %

RH 90 %

RH 80 %

0123456

0 28 56 84 112 140 168Time (days)M

ould

inde

x

30 C RH 100 %

RH 97 %

RH 90 %

RH 80 %


13

Predicted mould growth onpine sapwood in different

varied exposuresat RH 97 % and 75 %

0

123

45

6

0 2 8 5 6 8 4 1 1 2 1 4 0 1 6 8 1 9 6T im e (d a y s )

Mou

ld in

dex

C C o n s ta n t R H1 2 /1 2 h 9 7 /7 5 R H

6 /1 2 h 9 7 /7 5 R H

3 / 2 1 h 9 7 /7 5 R H

0123456

0 2 8 5 6 8 4 1 1 2 1 4 0 1 6 8 1 9 6T im e (d a y s )

Mou

ld in

dex

D

6 /4 2 h 9 7 /7 5 R H

7 /1 4 d 9 7 /7 5 R H

3 /4 d 9 7 /7 5 R H

7 /2 3 d 9 7 /7 5 R H

1 /6 d 9 7 /7 5 R H


14

Biohygrothermal model WufiBio

[Sedlbauer 2001]

Criteria for mould growth:"Material parameters" for a mould spore:


15

More models: Criteria for mould growth

[Sedlbauer & Krus 2003]

Generally, the models are•based on measured data

•regression analysis•isopleths•implementation of hygrothermal

calculation principles on mouldspores!

•isopleths and models are based onlaboratory results of test usingdifferent mould fungi and differentgrowth medium at regulatedhumidity and temperatureconditions

[Clarke et al 1999]


16

Mould growthExperiments

atTTY and VTT


17

THE OBJECTIVES OF THE TESTS

•to develop reliability and range of use of the existing mathematicalmodel in fluctuating temperature and humidity conditions

•to increase the number of material choices for the model•to test usage of the model by doing experiments for structures and

materials in laboratory and in field conditions

To formulate a more diversified and improved applicationof the existing VTT model for mould growth


18

TEST MATERIALS

Insulation materials

Glass woolPolyester woolEPSPU Stone materials

ConcreteAutoclaved aerated concreteExpanded clay aggregate concrete

Wood materialsEdge glued spruce boardPine sap wood (reference)

This study concentrates on materials and conditions which have not been testedor discussed in earlier studies.


19

MATERIAL EXPERIMENTS IN LABORATORY

97% RH / 20°CConstant90% RH / 5°CConstant90% RH / 22°CConstant97% RH / 5°CConstant97% RH / 5°CConstant

50% RH / 22°C97% RH / 22°CCycle 4 –8 weeks97% RH / 20°C97% RH / 22°CCycle 4 –8 weeks97% RH / 5°C97% RH / 22°CCycle 4 –8 weeks

97% RH / 22°CConstant

Test condition 2Test condition 1Constant/cyclicalconditions


20

Polyester wool, index 3PU (paper), index 3

Light aggregate concrete,index 3

Pine sap wood, index 5


21

MATERIAL EXPERIMENTS IN LABORATORY

Edge glued spruce board 97% RH/ 22 C

0

1

2

3

4

5

0 10 20 30 40 50 60 70

Weeks

Mou

ld in

dex

(05

)

uslspine uspine ls

Glass wool 97% RH/ 22 C

0

1

2

3

4

5

0 10 20 30 40 50 60 70

Weeks

Mou

ld in

dex

(05

)

usls

Edge glued spruce board 97% RH/ 22 Ccycle 20 C weeks 3744, 4954

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Weeks

Mou

ld in

dex

(05

)

uslspine us

vkot 3744 vkot4954

vkot 3744

Glass wool 97% RH/ 22 Ccycle 20 C weeks 3744, 4954

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Weeks

Mou

ld in

dex

(05

)

usls

vkot4954

vkot 3744

concrete, index 3 concrete, index 2


22

MATERIAL EXPERIMENTS IN FIELD CONDITIONS


23

MATERIAL EXPERIMENTS IN FIELD CONDITIONS

Spruce

0

1

2

3

4

5

6

27.1.2006 7.5.2006 15.8.2006 23.11.2006 3.3.2007

usls

us wetls wet

Polyurethane

0

1

2

3

4

5

6

27.1.2006 7.5.2006 15.8.2006 23.11.2006 3.3.2007

us paperls paperus groundls ground

Autoclaved aerated concrete

0

1

2

3

4

5

6

27.1.2006 7.5.2006 15.8.2006 23.11.2006 3.3.2007

us dryls dryus wetls wet

Pine sap wood

0

1

2

3

4

5

6

22.6.2006 30.9.2006 8.1.2007 18.4.2007

usls


24

STRUCTURE EXPERIMENTS IN LABORATORY

Cooling units

Heaters

Evaporator

EvaporatorStructureto be tested

Sprinklers andradiation heaterd

INSIDE OUTSIDE

Detectedinterface

concrete + expanded polystyreneconcrete + polyester wool

concrete + polyurethaneconcrete + glass wool

expanded clay aggregate concrete + expandedpolystyrene

expanded clay aggregate concrete + polyesterwool

expanded clay aggregate concrete + polyurethaneexpanded clay aggregate concrete + glass wool

edge glued spruce board + expanded polystyreneedge glued spruce board + polyester wool

edge glued spruce board + polyurethaneedge glued spruce board + glass wool

light concrete + expanded polystyrenelight concrete + polyester wool

light concrete + polyurethanelight concrete + glass wool

Second test seriesFirst test series


25

STRUCTURE EXPERIMENTS IN LABORATORY

RH tutkittavassa rajapinnassa

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

5.7.2006 24.8.2006 13.10.2006 2.12.2006 21.1.2007 12.3.2007 1.5.2007

Kevytbetonimuovikuitu Kevytbetonilasivilla Ksbetoni muovikuitu Ksbetoni lasivilla

Betoni muovikuitu Betoni lasivilla Kuusi muovikuitu Kuusi lasivilla

Lämpötila tutkittavassa rajapinnassa

10.00

5.00

0.00

5.00

10.00

15.00

20.00

25.00

30.00

5.7.2006 24.8.2006 13.10.2006 2.12.2006 21.1.2007 12.3.2007 1.5.2007

Kevytbetonimuovikuitu Kevytbetonilasivilla Ksbetoni muovikuitu Ksbetoni lasivilla

Betoni muovikuitu Betoni lasivilla Kuusi muovikuitu Kuusi lasivilla

Concrete Glass wool

0

1

2

3

4

5

6

22.6.2006 11.8.2006 30.9.2006 19.11.2006 8.1.2007 27.2.2007 18.4.2007 7.6.2007

M glass woolM concrete

Edge glued spruce board Glass wool

0

1

2

3

4

5

6

22.6.2006 21.8.2006 20.10.2006 19.12.2006 17.2.2007 18.4.2007 17.6.2007 16.8.2007

M glass woolM edge glued spruce board

Temperature RH


26

STRUCTURE EXPERIMENTS IN FIELD CONDITIONS

mould index = 0after 6 months

RHinterface =60 70% or80 90% (gw, pw)


27

Simulation of themould growth

on pine sap woodMATERIAL EXPERIMENTS IN FIELD CONDITIONS


28

BCs: Measured climate for the material tests in field conditions

201510

505

1015202530

0 5 10 15 20 25 30 35 40 45 50Weeks (June 22 May 2)

T,o C

0102030405060708090100

% R

H

48 per. Mov. Avg. (T)

48 per. Mov. Avg. (RH %)

Measured climate data in Tampere experiments


29

Decline of mould growth or not? VTT model

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

Measured (top)Measured (low)Normal declineDecline due to temp. onlyDecline when MO<1No decline

Mould prediction using nocapacity assumption Tampere climate data


30

Influence of moisture capacity of substrate: VTT model

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

Measured (top)Measured (low)TCCC2D, normal declineNocapacity + normal declineTCCC2d, no declineNocapacity, no decline

Mould prediction using nocapacity and dynamicsimulations Tampere climate data


31

Influence of BC's: VTT model

0

1

2

3

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

Measured (top)Measured (low)TCCC2D, normal convectionTCCC2D low convection

Mould prediction Tampere climate data


32

Comparison of VTT model and WufiBio

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

0

50

100

150

200

250

300

350

400

450

500

Wuf

iBio

gro

wth

, mm

Viitanen, normal declineViitanen, no declineMeasured (top)Measured (low)Viitanen, Espoo climateWufiBio, class 1

Comparison of Viitanen model and WufiBio resultsSolution using Tampere climatedata and TCCC2D simulations of

T, RH and Mo fields


33

Influence of substrate class. WufiBio

WufiBio:

Critical limits formaterial classes:

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

0

100

200

300

400

500

Wuf

iBio

gro

wth

, mm

Measured (top)Measured (low)WufiBio, class 0WufiBio, class 1WufiBio, class 2

Comparison of WufiBio results with different materialSolution using Tampere climate dataand TCCC2D simulations of T and RHfields

0

1

2

3

4

5

0 5 10 15 20 25 30 35 40 45 50Weeks (start June 22.)

Mou

ld g

row

th in

dex

MO

0

100

200

300

400

500

600

700

800

Wuf

iBio

gro

wth

, mm

Measured (top)Measured (low)WufiBio, class 0WufiBio, class 1WufiBio, class 2

Comparison of WufiBio results with different material classes

Solution using Tampere climate data andTCCC2D simulations of T and RH fields


34

A design case:A mould safe construction

DRYWEATHER DATA FOR JYVÄSKYLÄ, FINLAND


35

Calculation case: Construction

Construction from outside:

Jyväskylä weather

exterior sheatingventilated air cavity12 mm wood chip board150 mm mineral wool12 mm gypsum board

inside difusion resistances:Sd = 0 m, 1 m and 3 m

Criticalboundary


36

Isopleth (T RH) presentation from WUFI 4.0 Pro

70

75

80

85

90

95

100

10 5 0 5 10 15 20 25T, oC

% R

H

Sd,in = 1 m


37

Prediction of mould growthInfluence of diffusion resistance

VTT model (pine sap wood) vs. WufiBio (LIM I)

0

1

2

3

4

5

6

0 4 8 12 16 20 24 28 32 36 40 44 48 52Weeks (start Oct. 1)

Mou

ld g

row

th in

dex

Mo

Sd,in = 0Sd,in = 1 mSd,in = 3 m

0

100

200

300

400

500

600

700

800

0 4 8 12 16 20 24 28 32 36 40 44 48 52Weeks (start Oct. 1)

Gro

wth

, m

m

Sd,in = 0Sd,in = 1 mSd,in = 3 m

WufiBio growth prediction curves


38

Conclusion and Discussion!•Extensive experimental work on various materials and conditions•Existing models: predictability OK•Comparison of models: interesting.......

•How do we use mould prediction models?•Do we NEED these models?•The WORST CASE assumption? Consequences?•How detailed information?•Improvment points•Future focus

Documents

Mould€growth€in€building€materials Experiments€&€Modelling · 5.7.2006 24.8.2006 13.10.2006 2.12.2006 21.1.2007 12.3.2007 1.5.2007 Kevytbetonimuovikuitu Kevytbetonilasivilla