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Mold growth prediction with
Biohygrothermal Model
2
Contents:
Mold problems in practice
Growth Conditions
Steady State Model
Dynamic Model
Validation
Mold growth prediction with Biohygrothermal model
3
Mould on a thermal bridge
(concrete header joist)
Mold problems in practice
4
Mould at corners and edges
Mold problems in practice
5
Mould behind
interior
insulation slabs
(EPS)
Mold problems in practice
6
Growth conditions
7
Absidia glauca
Alternaria alternata
Alternaria sp.
Asp. amstelodami
Asp. candidus
Asp. chevalieri
Asp. flavus
Asp. fumigatus
Asp. nidulans
Asp. niger
Asp. penicillioides
Asp. repens
Asp. restrictus
Asp. ruber
Asp. terreus
Asp. versicolor
Aureobasidium pullulans
Botrytis cinera
Cla. cladosporioides
Fusarium culmorum
Fusarium oxysporum
Mucor plumbeus
Neurospora sitophila
Pen. bervicompactum
Pen. chrysogenum
Pen. citrinum
Pen. cyclopium
Pen. expansum
Pen. frequentans / glabrum
Pen. glabrum
Pen. italicum
Rhizopus stolonifer
Scopulariopsis brevicausalis
Stachybotrys atra
Trichoderma viride
Trichothecium roseum
Wallemia sebi
0 10 20 40 50 6030
Temperatur [°C]
Temperature range and
optimum for mould growth
Growth conditions
8
Relative Humidity [%]
Gro
wth
Ra
te µ
m/h
Humidity range for growth
of different mold species
Growth conditions
9
Aspergillus restrictus (Smith) Hygrothermal Iso-lines
for germination time
and growth rate of a
typical mould species
Growth conditions
10
Different Species
Aspergillus restrictus and other species
Growth conditions
11
Potentially hazardous mold species
need higher humidity to germinate
Re
lati
ve
Hu
mid
ity [
%]
Temperature [°C] Critical species: Aspergillus fumigatus Aspergillus flavus
Stachybotrys chartarum
Growth conditions
12
IBP mold growth test set-up:
Observation of the growth of a
typical mold cocktail on
different building materials
Growth conditions
13
Substrate Classification
II non biodegradable
building materials
I biodegradable building
materials
0 optimum substrate
Re
lati
ve
hu
mid
ity
[%
]
70
75
80
85
90
95
100 Lowest Isopleth for MoldDifferent species
00 55 1010 1515 2020 2525 3030
Temperature [°C]Temperature [°C]
Re
lati
ve
hu
mid
ity [
%]
70
75
80
85
90
95
100 Lowest Isopleth for MoldDifferent species
00 55 1010 1515 2020 2525 3030
Temperature [°C]Temperature [°C]
Growth conditions
14
Re
lati
ve
hu
mid
ity
[%
]
70
75
80
85
90
95
100 Lowest Isopleth for MoldDifferent species
00 55 1010 1515 2020 2525 3030
Temperature [°C]Temperature [°C]
Re
lati
ve
hu
mid
ity [
%]
70
75
80
85
90
95
100 Lowest Isopleth for MoldDifferent species
00 55 1010 1515 2020 2525 3030
Temperature [°C]Temperature [°C]
IEA-Annex 14 &
German Standard
DIN 4108: 80 %
Comparison
of LIM with
literature data
Growth conditions
15
Steady-state conditions
R 20
Steady State Model
16
Steady State Model
17
0
1
2 3
4
5
6
Steady state model for transient conditions ?!
Rela
tive H
um
idit
y [
%]
Fu
ng
al G
row
th [
mm
]
Transient conditions
Temperature [°C] Time [d]
Growth rate
Steady State Model
18
Dynamic model for
transient conditions
Dynamic Model
19
Water retention curve Spore wall permeance
Model spore
Dynamic Model
20
Definition of critical spore water content for germination
Dynamic Model
21
Factor Real life WUFI-Bio
Humidity &
Temperature
determining factors critical water content = f (φ,θ)
Time strong influence germination, growth rate = f(t)
Substrate availability of nutrients,
(concentration of growth
inhibiting chemicals)
LIM 0, LIM 1, LIM 2
material specific isopleths
pH-Value high pH is toxic not accounted for
Spore dissemination spores are ubiquitous in air spores are assumed to be present
Lethal conditions high and low temp. or low RH
may be lethal
decline not yet accounted for
>> evaluation should be confined to
12 month starting anytime within
the simulated period
Model assumptions of WUFI-Bio
Dynamic Model
Mold growth prediction with
Biohygrothermal Model
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