Avoiding mould growth in an interiorly insulated log wall

Alev, Üllar; Kalamees, Targo

doi:10.1016/j.buildenv.2016.05.020

Cited by 29 publications

(18 citation statements)

References 26 publications

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“…The installation of IWI may be an efficient solution to reduce the heat losses of uninsulated wall, yet is not always a risk-free intervention. Interstitial moisture may appear due to the installation of materials with low vapour permeability [6], the improper installation of equipment, such as HVAC components, [7,8], and when failing to seal around penetrations and services [8]. Furthermore, the improper installation of insulation at joist ends may contribute to moisture accumulation [9].…”

Section: Literaturementioning

confidence: 99%

Assessment of interstitial mould growth through impaction: a feasibility study

2020

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The application of insulation to solid walls is one of the measures to help reduce the energy consumption of a building. Where external wall insulation is not feasible (e.g. listed buildings), internal insulation may be the only option to improve the thermal property of external walls. However, such interventions may be followed by unintended consequences [1], such as moisture accumulation and the growth of mould [2]. The study aims to develop a method for the non-disruptive assessment of interstitial mould growth in internally insulated walls. Air sampling through impaction and culture-based analysis was used in the study. Mould species commonly found in buildings were cultivated and used in small-scale experiments, and the effects of several sampling periods and airflow rates assessed. Potential relationships between the sampling variables and the results were determined by means of statistical analysis - a strong correlation between the coverage of mould behind the wall and the sampling periods and airflow rates. The effect of the inertial impaction frequency on the sampling results and the feasibility and applicability of the suggested methodology in real-life scenarios are also discussed.

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Section: Literaturementioning

confidence: 99%

Assessment of interstitial mould growth through impaction: a feasibility study

2020

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“…The critical relative humidity, RH crit (%), originating from the widely used VTT model, was employed in this study. Similarly, Alev et al [23] carried out a study on avoiding mold growth in an interiorly insulated log wall in a cold climate, where no mold was accepted (i.e., MI < 1). As displayed in Figure 1, the RH crit suggests the lowest humidity required for mold growth on wooden materials.…”

Section: Model Equationsmentioning

confidence: 99%

“…For humidity control, the general mass conservation equation has been employed widely and presented in previous literature [21], indicating the crucial role of ventilation in transporting moisture between indoor and outdoor environments [22]. It is noted that heat and moisture are concurrently induced by outdoor ventilation and could remarkably affect the indoor air RH and temperature for mold growth [23,24]. In respect to the indoor thermal environment, occupants contribute themselves as an indispensable component of indoor heat and moisture sources.…”

Section: Introductionmentioning

confidence: 99%

Plum Rain-Season-Oriented Modelling and Intervention of Indoor Humidity with and without Human Occupancy

Qian

Zheng

et al. 2019

Atmosphere

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The plum rain season, caused by precipitation along a persistent stationary Mei-Yu front in East Asia, creates favorable temperatures and relative humidity (RH) for mold growth indoors. This paper investigates the effects of human occupancy on indoor humidity and investigates the efficient RH reduction methods to prevent mold growth in moist climates. The research is carried out based on a case study which compares a family-occupied home and another unoccupied one during typical plum rain season in Nanjing. Firstly, by analyzing the factors that can influence the indoor air RH, this paper develops a comprehensive model to evaluate the efficiency of various RH intervention methods. Secondly, this paper collects the meteorological data in Nanjing at different time scales, from days to hours. Thirdly, a specific case study is carried out based on the model and data. The results show that dehumidification and heating can always reduce RH below the critical value under which the mold growth could be inhibited. However, the effects of ventilation are more sophisticated and depend upon the human occupancy, outdoor air temperature, and air change per hour (ACH). In certain unoccupied cases, the ventilation may be inappropriate and may continuously bring moisture outside into the indoor environment, which has adverse effects on mold suppression. In the occupied cases, the condition changes significantly because the human is deemed as an internal source of heat and moist. Special care should be exercised for occupied ventilation in order to determine the optimal ACH and appropriate outdoor temperatures. Finally, some guidance is given to prevent mold growth in the general area that suffers from the plum rain season.

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“…Close consideration must be given to the hygrothermal performance of building assemblies, including mold growth, for the prevention of mold and moisture problems. Several studies on timber products (including CLT and OSB-oriented strand board) using hygrothermal simulations have been carried out [17][18][19][20][21][22][23][24]. In most of them, simulation calculations were performed using the WUFIa commercial hygrothermal simulation program (developed by Fraunhofer Institute for Building Physics).…”

Section: Introductionmentioning

confidence: 99%

Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates

Sadłowska-Sałęga

Wąs

2020

Buildings

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The paper is an attempt to answer the question whether the material-optimized roof construction using cross-laminated timber (CLT) is safe in terms of moisture content in the demanding northern costal climates. The proposed roof structure meets the strength requirements. The partition is diffusionally open, which facilitates moisture transport. However, there is a concern whether the applied layer system allows maintaining a safe level of moisture content below critical moisture content (CMC), which has been set at 20%. The article presents the annual hygrothermal calculation of the proposed roof slope for four locations of northern Europe and Greenland characterized by costal or subpolar climate. Four scenarios of indoor air relative humidity were considered: free floating, RHmin = 40%RH, RHmin = 50%, RHmin = 60%. In all cases, the minimum indoor temperature was 20 °C. The analysis was carried out using WUFI®Plus software. The calculation results showed that the moisture content did not exceed 20% in the CLT layer at any of the described locations. However, for the two coldest climates the assumed level of safety has been exceeded in the roof oriented strand board (OSB) sheathing.

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Avoiding mould growth in an interiorly insulated log wall

Cited by 29 publications

References 26 publications

Assessment of interstitial mould growth through impaction: a feasibility study

Assessment of interstitial mould growth through impaction: a feasibility study

Plum Rain-Season-Oriented Modelling and Intervention of Indoor Humidity with and without Human Occupancy

Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates

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