Tuomo Ojanen

Bio: Tuomo Ojanen is an academic researcher from VTT Technical Research Centre of Finland. The author has contributed to research in topics: Moisture & Building envelope. The author has an hindex of 16, co-authored 54 publications receiving 1565 citations.

Moisture and Bio-deterioration Risk of Building Materials and Structures

Abstract: There are several biological processes causing aging and damage to buildings. This is partly due to natural aging of materials and excessive moisture. The demands on durability, energy balance, and...

Moisture Buffering of Building Materials

Abstract: Building materials and furnishing used in contact with indoor air may have a positive effect to moderate the variations of indoor humidity seen in occupied buildings. Thus, very low humidity can be alleviated in winter, as well as can high indoor humidity in summer and during high occupancy loads. This way, materials can be used as a passive means of establishing indoor climatic conditions, which are comfortable for human occupancy, or for safe storing of artefacts which are sensible to humidity variation. But so far there has been a lack of a standardized quantity to characterize the moisture buffering capacity of materials. The objective of the NORDTEST project on Moisture Buffering of Building Materials has been to develop such a definition, and to present it in the form of a NORDTEST method. Apart from the definition of the Moisture Buffer Value, the project declares a test protocol which expresses how materials should be tested. The test protocol constitutes the project's proposal for a NORDTEST method, and can be seen as Appendix 1 of this report. Furthermore, as a part of the project some Round Robin Tests have been carried out on various typical building materials.

The effect of structures on indoor humidity – possibility to improve comfort and perceived air quality

Abstract: The research presented in this paper shows that moisture transfer between indoor air and hygroscopic building structures can generally improve indoor humidity conditions. This is important because the literature shows that indoor humidity has a significant effect on occupant comfort, perceived air quality (PAQ), occupant health, building durability, material emissions, and energy consumption. Therefore, it appears possible to improve the quality of life of occupants when appropriately applying hygroscopic wood-based materials. The paper concentrates on the numerical investigation of a bedroom in a wooden building located in four European countries (Finland, Belgium, Germany, and Italy). The results show that moisture transfer between indoor air and the hygroscopic structure significantly reduces the peak indoor humidity. Based on correlations from the literature, which quantify the effect of temperature and humidity on comfort and PAQ for sedentary adults, hygroscopic structures can improve indoor comfort and air quality. In all the investigated climates, it is possible to improve the indoor conditions such that, as many as 10 more people of 100 are satisfied with the thermal comfort conditions (warm respiratory comfort) at the end of occupation. Similarly, the percent dissatisfied with PAQ can be 25% lower in the morning when permeable and hygroscopic structures are applied.

Improved model to predict mould growth in building materials

Abstract: Mold growth is one of the first signs of biological growth linked to too high local moisture content in structures. The numerical mold growth model was based on comprehensive laboratory studies with northern wood species, and it could be used to predict the mold growth in structures. The mold growth is presented as a mold index that may have values between 0 and 6, and it is solved from the changing temperature and humidity conditions. This model can be used as a part of heat, air, and moisture transfer models or to post-process the data derived from simulations or experiments. The numerically solved mold index can be used as one criterion for the moisture performance of the analyzed structure. The main deficiency of the model is that it includes only wood material as the mold growth breeding ground. This study presents new results for modeling of mold growth on the surface of other building materials, such as gypsum board, cement screed on concrete, porous wood fiberboard, and spruce plywood. In addition to extended material data, some evaluations were carried out to better predict the dynamic effect of humidity on the mold growth. This study is active, and further information about the effect of changing dry and cold conditions on the regression and recovery of mold growth will be produced in the new project.

Towards modelling of decay risk of wooden materials

Abstract: An empirical model for wood decay development which can be incorporated into a hygrothermal model of building physics is presented. The model is applied to the ERA-40 reanalysis data, based on six-hour weather observations in Europe, to estimate wood decay in different parts of Europe. These studies provide new tools for evaluating the durability and service life of wooden products and a preliminary European wood decay risk level map. The effects of the projected climate change on wood decay may also be considered by this methodology.

Impact of indoor environmental quality on occupant well-being and comfort: A review of the literature

Abstract: Indoor environmental quality (IEQ) and its effect on occupant well-being and comfort is an important area of study. This paper presents a state of the art study through extensive review of the literature, by establishing links between IEQs and occupant well-being and comfort. A range of issues such as sick building syndrome, indoor air quality thermal comfort, visual comfort and acoustic comfort are considered in this paper. The complexity of the relationship between occupant comfort and well-being parameters with IEQ are further exacerbated due to relationships that these parameters have with each other as well. Based on the review of literature in these areas it is established that design of buildings needs to consider occupant well-being parameters right at the beginning. Some good practices in all these different areas have also been highlighted and documented in this paper. The knowledge established as part of this paper would be helpful for researchers, designer, engineers and facilities maintenance engineers. This paper will also be of great benefit to researchers who endeavour to undertake research in this area and could act as a good starting point for them.

The Ecology of Building Materials

Abstract: Part 1 Eddies and water-level markers: technology and work material resources energy resources pollution economy and efficiency chemical and physical characteristics of building materials. Part 2 The flower, the iron and the sea: water and air minerals - natural stone and loose mass minerals - natural stone, mixed loose mass fossil oils vegetable raw materials animal substances industrial bi-products. Part 3 The sea-iron flower: construction materials climatic materials surface materials other components compounds impregnation, or how to avoid it the first steps. Notes to an epilogue.

Associations between fungal species and water-damaged building materials.

Abstract: Fungal growth in damp or water-damaged buildings worldwide is an increasing problem, which has adverse effects on both the occupants and the buildings. Air sampling alone in moldy buildings does not reveal the full diversity of fungal species growing on building materials. One aim of this study was to estimate the qualitative and quantitative diversity of fungi growing on damp or water-damaged building materials. Another was to determine if associations exist between the most commonly found fungal species and different types of materials. More than 5,300 surface samples were taken by means of V8 contact plates from materials with visible fungal growth. Fungal identifications and information on building material components were analyzed using multivariate statistic methods to determine associations between fungi and material components. The results confirmed that Penicillium chrysogenum and Aspergillus versicolor are the most common fungal species in water-damaged buildings. The results also showed Chaetomium spp., Acremonium spp., and Ulocladium spp. to be very common on damp building materials. Analyses show that associated mycobiotas exist on different building materials. Associations were found between (i) Acremonium spp., Penicillium chrysogenum, Stachybotrys spp., Ulocladium spp., and gypsum and wallpaper, (ii) Arthrinium phaeospermum, Aureobasidium pullulans, Cladosporium herbarum, Trichoderma spp., yeasts, and different types of wood and plywood, and (iii) Aspergillus fumigatus, Aspergillus melleus, Aspergillus niger, Aspergillus ochraceus, Chaetomium spp., Mucor racemosus, Mucor spinosus, and concrete and other floor-related materials. These results can be used to develop new and resistant building materials and relevant allergen extracts and to help focus research on relevant mycotoxins, microbial volatile organic compounds (MVOCs), and microparticles released into the indoor environment.