Mold and Moisture Transfer in Building Structures and Buildings with Particular Regard to the Prevention of Health Hazards

Principal investigator: Prof. Olli Seppänen, Helsinki University of Technology, HVAC-Laboratory, E-mail:

The aim of the research project is to work out calculation facilities for mould transfer through constructions and inside the buildings, and to produce solutions and basis for solving mould and moisture problems by using pressurisation and insulation techniques with particular regard to moisture and mould transfer and health aspects. The following tasks are included in the research. 1. To work out mould transfer models by which both the spreading of the metabolic products and the mould spores in the constructions and inside the building can be modelled. 2. To give guidelines and limits on how to use pressurisation and insulation as repairing measures for preventing mould transfer. 3. To analyse possible side effects, moisture behaviour of constructions and mould growth caused by changing pressure conditions and, respectively, to produce guidelines with regard to moisture behaviour and mould growth. 4. To develop a new serum IgG avidity test in order to estimate the exposure to moulds in cross-sectional and follow-up studies.

Theoretical models for estimating the risk of occurrence of mould growth, growing and spreading of the mould and models for the moisture transfer will worked out. Models for spreading of mould will consider both particles (mould spores) and gases (metabolic products). Moisture transfer models will include the modelling of moisture convection and diffusion, but not water contact. Conditions for mould growth and material properties effecting on mould growth that are initial parameters for the estimating the mould growth, are mostly taken from other studies and literature. Laboratory tests and field measurements (in single-family and apartment houses) are used for developing and validation of the models. All developed mould and moisture models can be simultaneously used with traditional heat transfer and air flow models in modular simulation environment IDA.

Health hazards caused by microbes and water damages are studied by measuring the exposure of residents in test houses with new clinical methods. In addition to measuring the exposure, the purpose of clinical methods used is to estimate the time period, when the exposure to mould allergens has occurred. The state of residents' health is studied with epidemiological examinations. The same medical examinations are made before and after repairing measures and also in "clean" houses.

The behaviour of repairing solutions, worked out in the research, will be shown with computer simulations by using developed models and with laboratory and field measurements. The effect of the overpressurising will be analysed by studying the drop of contaminant concentrations, caused by changed direction of air flows (leakage), and also the change in moisture behaviour, caused by possible moisture convection, will be studied. In addition to measuring moisture conditions, the behaviour of mould growth will be studied by laboratory measurements and computer calculations. The important properties of constructions that make it possible to use the pressurising will be given and construction solutions where pressurising cannot be used will be outlined by examples.