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M. Krus, K. Sedlbauer
Mold Growth Prediction byComputational Simulation
Problems caused by mould fungi
Mould growth on inner surfaces
Problems- health risks- financial risks (in Germany 200 Mio € / p. year)
Aims- Planning tool for prevention of mould growth
- Consideration of transient boundary conditions
additional Requirements- Consideration of all fungal species found on building surfaces
- Consideration of different substrate classes
Methodicals
requirements for growth ofmold fungi
temperature, humidity,substrate, time
unsteady hygrothermalconditions of building
environment
comparison by using new models
prediction of moldgrowth
Isopleths modelBiohygrothermal
Model
Isopleth systems
Aspergillus restrictus (Smith)
Development of the Lowest Isopleth for Mould (LIM)
Lowest Isopleth for MouldDifferent Species
Development of the Lowest Isopleth for Mold (LIM)R
ela
tive h
um
idit
y [
%]
70
75
80
85
90
95
100 Lowest Isopleth for MoldDifferent species
00 55 1010 1515 2020 2525 3030
Temperature [°C]Temperature [°C]
Germination Mycelial growth
Test station for mould fungi
LIMs for different building products
Substrate Groups
II biological adverserecycable materials
I biological recycablematerials
0 optimum cultures medium
Temperature [°C]
Rela
tive h
um
idit
y [
%]
100
Isopleth systems for different building products
Isopleth system for the critical fungus species
Critical fungus species:
Aspergillus fumigatus
Aspergillus flavus
Stachybotrys chartarum
Humidity in Rooms
500 - 1500
(min. 12 liters/day)Total flat (100 m²)
30Person, light activity
5 - 20Rubber plant
2 - 10Violets
Flowers
Delivery of humidityper hour [g/h]
Source of humidity
Ventilation by Windows?
Surface temperature on outer walls
Use of the Isopleth System
0
1
23
4
5
6
Germination and mycelial growth
REM-Picture of Mould Spores
Biohygrothermal Model
Hygrothermal "material properties" of the model spore
Hygrothermal "material properties" of the model sporeR
ela
tive
hu
mid
ity
[%
]
0 5 10 15 20 25 30
Temperature [°C]
70
75
80
85
90
95
100
Example: new buildings with mould on outer surfaces
Mold in all 4 orientations
broad infestationsat the lintels
circular infestations
Example: new buildings with mould on outer surfaces
Concrete
Mineral wool
Polystyrol
Plaster(synth. Resin)
Air gap
Example: new buildings with mould on outer surfaces
Monat
rela
tive L
uftfe
uchte
im
Auß
enpu
tz [%
]
60
65
70
75
80
85
90
95
100
Monat
rela
tive L
uftfe
uchte
im
Auß
enpu
tz [%
]
60
65
70
75
80
85
90
95
100
ungestörter Bereichbeim Luftspaltbeim Fenstersturz
X XI XII I II III IV V VI VII VIII IX
normal wallnear air gaplintelR
el. H
um
idity
of th
epla
ste
r[%
]
Month
Example: new buildings with mould on outer surfaces
normal wallnear air gaplintel
Summary
model for prediction of mold growth- Isopleths model
- biohygrothermal system
innovations- health risk classes- substrate groups- unsteady implementation
validation good agreement- with experiences- with laboratory experiments
- with test field results
general characteristics- usable as design tool for practitioners- preventive aspects
Field test area in Holzkirchen, Germany
