fungi: growth and growth model

The prediction of the germination and growth potentials or rates of molds in buildings had been the target of several research projects and on the wish list of many others. These models are quite an achievement, considering the complexity of the biological or mycological mechanisms involved. The results of these models may currently be used to indicate the potentials or for comparisons. They are yet to be verified, and more data are needed for the variety of the building materials, and more mechanisms to be revealed and modeled..

Mold index: 0 to 6

The model is mostly developed for wood, but can be used to estimate the risks for mold growth risk on any material surface and it can be used as a moisture performance criterion together with moisture content levels of materials. Ojanen, T., 1998, Improving the drying efficiency of timber frame walls in cold climates, by using exterior insulation

Mold growth model:

A numerical model to calculated the model growth in building envelopes under indoor / outdoor conditions. Model is based on some measurements of mold growth under steady-state and alternating (e.g. 6 hour low rh and 12 hour high rh) conditions of temperature and relative humidity. For limited wood species and fungus species. It is the widely used as the base for mold damage predictions in many HAM models. Viitanen, H., 1996, Factors affecting the development of mould and decay in wooden material and wooden structures and other references.

Mold germination model:

The biohygrothermal model for spore germination is a truly genuine approach to model the germination process. The spore layer on material is consider as a hygroscope material layer. It will increase in moisture contents if placed in relative humidity conditions. The concepts of moisture transport are mapped for spore layer. Though much of the spore hygrothermal properties remain to be measured/estimated. Krus, M., Sedlbauer, K., Zillig, W. and Kunzel, H.M., 2001, A new model for mould prediction and its application on a test roof

Limit condition model

Data generated from literature (256 references) and testing. Concentrate on minimum conditions (RH, T) for mold growth. Distinguish among 6 categories of molds, according to levels of limit conditions. Clarke et al. 1998, A technique for the prediction of the conditions leading to mould growth in buildings

HAM integrated model:

The mold growth model had been integrated into the HAM code to simulate the mold occurrence or risk in design stage. Most cases of integration is to add mold growth as kind of post-processing - using the T and RH solution profiles to calculate the mold growth values/rates. Since there are insufficient data on the growth rates of molds for different species and for various conditions, The calculated rates are not claimed as the predicted rates of the mold growth. Rather, the calculated results are used as indicator for the potential that mold may grow for the wall under study and conditions used in the simulation. Example: Clarke, J. A., Johnstone, C. M., Kelly, N. J., Mclean, R. C. and Nakhi, A. E., 1997, Development of a simulation tool for mould growth prediction in buildings into ESP-r. Karagiozis, 2002, A North American research approach to moisture design by modeling for HAM: WUFI-ORNL/IBP.

A particular case of the integration is one developed be Sedlbauer. He model to implement mold growth/germination using one hypothetic layer in the wall assembly, that layer behavor mostly like a hygroscopic material except the parameters are related to molds and concentration/potentials are mold growth/germination. Initially, this method is thought as a convenient way for the author to implement the mathematical model he obtained from experimental data on mold growth. However, the idea of a mold layers (or substrates) on the surfaces of material layers seems to stand out and be easier to accept on its own. See references Sedlbauer, 2002, Prediction of mould fungus formation on the surface of and inside building components. ,, Sedlbauer, 2002, Prediction of mould growth by hygrothermal calculation and Krus, M., Sedlbauer, K., Zillig, W. and Kunzel, H.M., 2001, A new model for mould prediction and its application on a test roof,, and Rowan et al., 1999, Prediction of toxigenic fungal growth in buildings by using a novel modelling system

Subtrate Classes

SedlBauer divided substrate to four groups. Growth data needed for each substrate. Sedlbauer, K., 2002, Prediction of mould growth by hygrothermal calculation

Tidbits

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A presentation of the German model.

Mold: The Whole Picture - Abbey Newsletter

A 4 series of articles on mold by Ellen McCrady: The Whole Picture Pt. 1; Pt. 2, Assessment of Mold Problems; Pt. 3, A Neglected Public Health Problem; Part 4: Effect of Mold on Schools, Homes, & Human Beings

a comprehensive model at VTT

A mathematical model of mold growth on wooden material, by Hukka, A. and Viitanen H., 1999

germination model, biohygrothermal model

A new model for mould prediction and its application on a test roof, by Krus, M., Sedlbauer, K., Zillig, W. and Kunzel, H.M, 2001

non-steady state

A new model for mould prediction and its application on dwellings with mould on the outer facades, by Sedlbauer, K., Krus, M. and Zillig, W., 2002

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A North American research approach to moisture design by modeling, by Karagiozis, A., 2002

conditions leading to mould growth

A technique for the prediction of the conditions leading to mould growth in buildings, by Clarke, J. A., C. M. Johnstone, N. J. Kelly, R. C. McLean, J. A. Anderson, N. J. Rowan, and J. E. Smith, 1999

by mycologist, at optimal T

A temperature-type model for describing the relationship between fungal growth and water activity, by Sautour, M., Dantigny, P., Divies, C., Bensoussan, M., 2001

effect of temperature and humidity

Combined effect of temperature and humidity of the detoriation process of insulation materials in ETICS, by Holm, A. and K¨ąnzel, H.M, 1999

anti-fungal paints

Control of mould growth by anti-fungal paints, by Heaton, P.E., Callow, M.E., Butler, G.M. and Milne, A., 1991

collection of models and analysis

Criteria for moisture control, by Brundrett, G. W., 1990

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D6329-98 standard guide for developing methodology for evaluating the ability of indoor materials to support microbial growth using static environmental chambers, by ASTM, 2002

mold survival

Decay of wood and wood-based products above ground in buildings, Mechanism of Brown-Rot Decay: Paradigm or Paradox, by Carll, C. G. and Highley, T. L., 1999

logevity of spore

Development of a model to predict the effect of temperature and moisture on fungal spore longevity, by Hong, T. D., Ellis, R. H. and Moore, D., 1997

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Development of a simulation tool for mould growth prediction in buildings, by Clarke, J. A., Johnstone, C. M., Kelly, N. J., Mclean, R. C. and Nakhi, A. E., 1997

fungal damage model IRC

Durability assessments of wood-frame construction using the concept of damage-functions, by Nofal, M. and M.K. Kumaran, 1999

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Environmental requirements for fungi, by Janinska, B., 2000

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Factors affecting mould growth on kiln dried wood, by Viitanen, H., 2001

Viitanen thesis on mold growth

Factors affecting the development of mould and decay in wooden material and wooden structures, by Viitanen, H., 1997

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Fungal growth and survival in building materials under fluctuating moisture and temperature conditions, by Pasanen, A. L., J. P. Kasanen, et al., 2000

risk of mold growth on wooden structures in crawl spaces

Fungal growth on wood surfaces at different moisture conditions in crawl spaces, by Pasanen, P.O. et al, 2001

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Growth of mold on fiberglass insulation materials--a review of the literature, by Van Loo, J. Robbins, C. Swenson, L. and Kelman, B., 2004

under different humidities

Growth of moulds on building materials under different humidities, by Nielsen, K. F., Nielsen, P. and Holm, G., 2000

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How quickly must gypsum board and ceiling tile be dried to preclude mold growth after a water accident?, by Horner, W. E., Morey, R. and Ligman, D. B. K., 2004

humidity requirement

Humidity requirements for mold growth, by Block, S. S., 1953

use VTT mold model to predict

Improving the drying efficiency of timber frame walls in cold climates, by using exterior insulation, by Ojanen, T., 1998

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Information and Technology Transfer from IBP: Mold Growth on ETICS (EIFS) as a Result of "Bad Workmanship"?, by Sedlbauer, K. and Krus, M., 2002

growth and decay

Modeling mould growth and decay damages, by Viitanen, H., Hanhijarvi, A., Hukka, A., Koskela, K., 2000

implement growth by wall layer

Mold growth prediction by computational simulation, by Sedlbauer, K., Krus, M., Zillig, W. and K¨ąnzel, H. M., 2001

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Numerical simulation of mould growth in timber frame walls, by Ojanen, T. and M. Salonvaara, 2000

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Occurrence and moisture requirements of microbial growth in building materials, by Pasanen, A.-L., Juutinen, T., Jantunen, M. J. and Kalliokoskia, P., 1992

as biological damage function

On implementing experimental biological damage-functions models in durability assessment systems, by Nofal, M. and M.K. Kumaran, 2000

decay rate, preliminary study

Predicting decay rates in structures: the effects of wood moisture content on decay rate, by Morrell, J. J., 2000

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Prediction of mould fungus formation on the surface of and inside building components, by Sedlbauer, K., 2002

implement growth by wall layer

Prediction of mould growth by hygrothermal calculation , by Sedlbauer, K., 2002

growth limit curves of min T and RH, good references

Prediction of toxigenic fungal growth in buildings by using a novel modelling system, by Rowan, N.J., Johnstone, C.M., McLean, R.C., Anderson, J.G. and Clarke, J.A., 1999

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Report of microbial growth task force, by AIHA, 2001

homidity on mold growth

Response of fungi to transient relative humidities, by Adan, O. C. G., 1995

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Static chamber method for evaluating the ability of indoor materials to support microbial growth, by Foarde, K. K., Vanosdell, D. W. and Chang, J. C. S., 1996

use microcalorimetry to measure

Studies of the degratation of building materials by isothermal microcalorimetry, by Wadso, L., 1996

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The moisture requirements of moulds isolated from domestic dwellings , by Grant, C., Hunter, C. A., Flannigan, B. and Bravery, A. F., 1989

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The relationship between measured moisture conditions and fungal concentrations in water-damaged building materials, by Pasanen, A. L., S. Rautiala, et al., 2000

response

The response of building materials to the mould exposure at different response conditions, by Ritschkoff, A., Viitanen, H., and Koskela, K., 2000

of MVOC

Volatile compounds originating from mixed microbial cultures on building materials under various humidity conditions, by Korpi, A. Pasanen,A.L. and P. Pasanen, 1998

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Wood in the built environment - conditions for mold and decay, by Anagnost, S. E., 2007