Modeling to predict positive pressurization required to control mold growth from infiltration in buildings in a hot and humid climate

Chen, Wei Jen; Claridge, D. E.; Rohrs, Chae; Liao, Jiajun

doi:10.1016/j.buildenv.2016.05.001

Cited by 9 publications

(5 citation statements)

References 13 publications

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“…A literature cross-check or comparison for our findings would be a nice addition to this section; however, it is actually difficult to find comparable studies. As discussed in the introduction, Chen et al (2016) examined a hot humid climate, with results that are rather complementary to ours.…”

Section: Discussionsupporting

confidence: 54%

“…The effect of a positive pressure on the moisture accumulation in the building envelope was examined in Chen et al (2016) for a hot humid climate. The authors found that a small positive pressure in the range 1–2 Pa can reduce the amount of infiltration-induced moisture for all walls, and observed an according negative change in the annual mould index value.…”

Section: Introductionmentioning

confidence: 99%

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Positive pressure effect on moisture performance in a school building

Ferrantelli

Vornanen-Winqvist²,

Mattila³

et al. 2019

Journal of Building Physics

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Moisture excess in buildings constitutes a complex problem affecting indoor air quality, energy consumption and the lifetime of the building envelope. We investigate the effect on moisture transfer in structures as a positive pressure is applied inside the enclosure. It is found that, contrary to established belief, the positive pressure does not induce any negative effects on the structures’ moisture content in normally ventilated classrooms, even with high occupancy. Our case study consists of a school building in Finland, subject to temperature and relative humidity measurements after a small (5–7 Pa) positive pressure was realized through ventilation control. We first address analytically the moisture excess generated inside the classrooms for 14 days, using dynamical balance equations that account for both ventilation effects and occupants’ moisture release in the environment. It is found that the average moisture excess is very small, largely below 1 g/m3, even for ventilation rates that are half the design value. We also examine the moisture performance of the envelope, by addressing the moisture migration at upper and lower joints of the external walls for both measured and design values of the indoor absolute humidity (AH). A coupled numerical model of diffusion and convection shows that moisture accumulation in the envelope and the according stresses are negligible for any realistic AH values. This result is in agreement with field measurements at the school. In conclusion, it seems that applying a small overpressure in a well-ventilated school building during a standard service period resulted in no accumulation inside the external walls, even at high occupancy and with low ventilation. Remarkably, it slightly dried out the moisture content in structures under actual occupancy conditions. The positive pressure has accordingly no negative effects on moisture performance, and is capable to guarantee a good indoor air quality as well.

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Section: Discussionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Positive pressure effect on moisture performance in a school building

Ferrantelli

Vornanen-Winqvist²,

Mattila³

et al. 2019

Journal of Building Physics

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“…The pressurisation is another way to keep moisture out by the positive pressure between indoor and outside (Chen et al, 2016). Nevertheless, this method is only useful for a limited space rather than a whole building because static pressures in the same building differ from one space to another, due to the stack effect and the HVAC operation (ASHRAE, 2009).…”

Section: Ventilation Air Conditioning and Pressurisation (Vacp)mentioning

confidence: 99%

Untitled

2020

JCDC

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Indoor mould is usually discussed for the building operation phase rather than the design stage. Moreover, the majority of existing studies were conducted by mechanical engineers rather than architects, who typically have a broader view of the whole project. The purpose of this article is to obtain a quantitative mould risk scenario across the Yangtze River Delta in China and make a matrix including all the possible design options to reduce the mould risk. A series of software is utilised to simulate the mould risk in three main cities across that region. Simulation results confirm high mould risk in all selected cities and the mould growth rates in different orientations match the Wind-Driven Rain diagram. After the simulation, all factors that can be tuned for the mould prevention were analysed. It is found that only humidity and substrate (material of finishing layer) characteristics can be practically controlled for mould avoidance. Meanwhile, the development design stage is the essential design phase while the envelope is the most crucial building element for mould prevention.

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“…One of the techniques for limiting mold growth in most of the large buildings in the US is building pressurization. A study (29) suggests that for spaces modelled in a hot and humid climate, the effective solution is positive pressurization and keeping a higher setpoint of indoor temperature. Another way is to increase the amount of pozzolana in a lime plaster mixture.…”

Section: Introductionmentioning

confidence: 99%

Moisture Buffering and Mold Growth Characteristics of Naturally Ventilated Lime Plastered Houses.

Paralkar

Damle

2022

Preprint

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Lime plaster is well known for its moisture buffering capabilities but is also susceptible to mould growth. This work focusses on the hygrothermal performance of lime plaster in naturally ventilated residential spaces. Surveys are carried out for 45 traditional buildings of Ahmedabad in India with measurements of ambient variables, such as temperature, relative humidity, wall moisture content, etc. Mould growth patterns of these spaces are related to the measured variables and wall characteristics. Hygrothermal simulations of some spaces are also carried out to observe the moisture buffering of lime plaster. Experimental observations are contrasted with simulation results to see if numerical predictions are realistic.

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Modeling to predict positive pressurization required to control mold growth from infiltration in buildings in a hot and humid climate

Cited by 9 publications

References 13 publications

Positive pressure effect on moisture performance in a school building

Positive pressure effect on moisture performance in a school building

Untitled

Moisture Buffering and Mold Growth Characteristics of Naturally Ventilated Lime Plastered Houses.

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