A new model for mould prediction and its application in practice

Sedlbauer, Klaus; Krus, Martin

doi:10.1201/9781003078852-128

Cited by 18 publications

(35 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, several numerical engineering models attempting to capture the complexity of mold growth on building materials were developed. The two most advanced models were published by Viitanen and Ojanen (2007) and Sedlbauer (2001). Both the models are based on a series of steady-state laboratory experiments, where the material samples are in hygrothermal equilibrium with ambient air.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigations of wooden beam ends in masonry with interior insulation: Measured data in real-scale experimental walls exposed to semi-continental climatic conditions

Kopecký

Staněk

Bureš

et al. 2019

Journal of Building Physics

View full text Add to dashboard Cite

This article deals with the hygrothermal performance of wooden beam ends embedded in brick masonry walls. The real-scale experiment involving three interior insulation systems with different water vapor resistances and different treatments of joist pockets was monitored for three consecutive years. The moisture load of test walls was controlled during the experiment. First, humidity of indoor air was increased in the cold season (2016–2017). Then, an artificial short-time intensive rain event brought liquid water onto the external surface of the test walls in July 2017. Despite relatively mild external climatic loads, relative humidity was unsatisfactorily high in unsealed joist pockets. Vapor and airtight sealing of the joist pockets improved the microclimate of the wooden beam ends. However, even in this case, relative humidity approached critical values for the onset of mold growth. The artificial rain load applied on the experimental walls noticeably worsened the hygrothermal conditions in the joist pockets. Relative humidity in the joist pockets further increased to a level where massive mold growth could be expected. Visual inspection of the wooden beam ends during reconstruction of the experiment, however, revealed only a small spot of mold on a single beam located in an unsealed joist pocket. Mold growth on samples of organic thermal insulation material was found by microscopic investigations. Molds were localized in small separated colonies. These in situ and laboratory investigations do not confirm the calculated values of mold growth index. In conclusion, sealing of wooden beam ends improved their hygrothermal performance in the experiment.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental investigations of wooden beam ends in masonry with interior insulation: Measured data in real-scale experimental walls exposed to semi-continental climatic conditions

Kopecký

Staněk

Bureš

et al. 2019

Journal of Building Physics

View full text Add to dashboard Cite

show abstract

“…Molds do not typically grow in temperatures below 0°C (Hukka and Viitanen, 1999; Sedlbauer, 2001); thus, considering the duration for which Finland experiences outdoor temperatures between 0 and 5°C (Finnish Meteorological Institute, 2021b), a small amount of mold (MI value 2–3) may develop during autumn or spring on very sensitive building materials if a low-Γ wall is subjected to a significant amount of air exfiltration from a point defect (Figure 9). This risk seems to be slightly higher in South Finland, where the outdoor temperature is between 0 and 5°C for 61 days of the year, while, in North Finland, such temperatures occur for 49 days.…”

Section: Resultsmentioning

confidence: 99%

“…Viljanen and Lu, 2019). Temperatures of 25–30°C promote the fastest growth rate of various mold fungi (Sedlbauer, 2001) but prevent the emergence of high RH levels in the exterior parts of walls subjected to exfiltration. As the outdoor temperatures of 1–5°C in Espoo, Jyväskylä, and Pudasjärvi, are linked to outdoor RHs 75%–90%, 65%–95%, and 70%–90%, respectively, the dehumidification in the outdoor chamber in the MCON1 test was set to 80% RH.…”

Section: Methodsmentioning

confidence: 99%

Hygrothermal performance of highly insulated external walls subjected to indoor air exfiltration

Viljanen

Puttonen

Lü

2022

Journal of Building Physics

View full text Add to dashboard Cite

The study comprises three laboratory tests in which typical Finnish highly insulated (HI) walls were exposed to concentrated leakages of indoor air under steady outdoor temperatures of 1–5°C. Airflows with a relative humidity of 50% and at rates of 1–3 L/min were directed close to the wooden frames inside the walls. The thermal resistance ratios between the exterior sheathing(s) and the whole wall (Γ) were 20%–22% and 1%–10% for the HI and baseline (BL) walls. The HI walls that presented Γ values of at least 20% were observed to be resistant to air exfiltration, and their durability was not affected by the addition of a gypsum sheathing outside the wooden frame or a more permeable vapor retarder. This is related to the negative linear correlation that exists between the moisture accumulation rate in wood-based material and the dew point depression (DPD) value. The developed approach, called the DPD method, shows that a significant degree of moisture accumulation does not occur even for DPD values of as low as −2°C if the exterior sheathing is vapor permeable. The airflow does not penetrate into the rigid mineral wool sheathing, which helps to avoid interstitial condensation. Regardless of thermal transmittance, the HI and BL walls with maximum Γ values of 1% were exposed to a high relative humidity and even interstitial condensation because the DPD values were often below −2°C. For these walls, the mold index analysis and visual observations confirmed the local risk for mold growth on the opposite side of the leakage point. In practice, long-term mold growth may be limited if the seasonal periods during which the outdoor temperature is 1–5°C last for a maximum of about 1 month every year.

show abstract

“…Fig. 1.a shows, on a psychometric chart, the threshold values of temperature, specific humidity and relative humidity over which spore germination or mould growth occur on paper, according to Sedlbauer model [30,31]. As for chemical degradation mechanisms in paper, it is usually driven by acid hydrolysis [29], which leads to discoloration and embrittlement of paper and deterioration in text [4].…”

Section: Methodsmentioning

confidence: 99%

A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis

Schito

Pereira

Testi

et al. 2019

Journal of Cultural Heritage

View full text Add to dashboard Cite

The study presents a new procedure for identifying possible risks for books kept in historic libraries. It is addressed to all those historic libraries where large collections of old and rare books are stored and preserved. These libraries were rarely used by people, but, nowadays, many of them have become touristic attractions. Consequently, their indoor microclimate may have changed, possibly leading to risks for books conservation. The proposed methodology is based on an intensive monitoring campaign, followed by an in-depth data analysis. Handy indices are also proposed to guide the researchers in the identification of possible risks. Problems related to too-high daily or spatial hygrothermal variations or problems related to specific risks (e.g., biological or chemical risks) can be identified. If a problem is observed, the identification of the most suitable solutions is more straightforward. The application of the proposed procedure to a real case study (the Baroque Library of the University of Coimbra, Portugal) has highlighted its handiness. A 6-month monitoring campaign and its consequent data analysis has pointed out potentially risky situations. Thus, measures should be taken to avoid books damage. Primarily, local actions are suggested.

show abstract

A new model for mould prediction and its application in practice

Cited by 18 publications

References 1 publication

Experimental investigations of wooden beam ends in masonry with interior insulation: Measured data in real-scale experimental walls exposed to semi-continental climatic conditions

Experimental investigations of wooden beam ends in masonry with interior insulation: Measured data in real-scale experimental walls exposed to semi-continental climatic conditions

Hygrothermal performance of highly insulated external walls subjected to indoor air exfiltration

A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis

Contact Info

Product

Resources

About