Effective moisture penetration depth model for residential buildings: Sensitivity analysis and guidance on model inputs

Woods, Jason; Winkler, Jon

doi:10.1016/j.enbuild.2018.01.040

Cited by 23 publications

(20 citation statements)

References 13 publications

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“…To substantiate the estimate of 1.7 L/h, we cite results from two studies. In a home in North Carolina, Duncan et al 32 reported that “about 2.2 ± 0.2 L of water vapor was condensed in the air conditioning system during each cooling cycle, approximately hourly.” An unoccupied house in Fort Wayne, Indiana, with volume of 490 m 3 , had a mechanical ventilation rate of 119 m 3 /h 33 . The measured air‐conditioner condensate flow spanned a range up to 40 L/d, equivalent to 1.7 L/h.…”

Section: Indoor Watermentioning

confidence: 99%

“…However, even with its much lower capacity, the amount of sorbed water associated with gypsum board is substantial. Consider a room of dimensions 3 × 4 × 2.3 m, for which the walls and ceiling are covered by gypsum board of thickness 33 13 mm and density 38 690 kg/m 3 . In this room volume of 28 m 3 , the total area of walls plus ceiling is 44 m 2 , which would be covered with about 400 kg of gypsum board.…”

Section: Indoor Watermentioning

confidence: 99%

“…The resulting apportionment was 33% wallpaper, 21% painted surface, 18% textile furnishings, 15% wood, 8% synthetic flooring, and 4% textile carpets. Woods and Winkler 33 reported the major categories of surface areas for moisture‐buffering materials in three unoccupied homes they studied. With volumes in the range 235‐490 m 3 , the corresponding area/volume ratios were 1.23‐1.29 m 2 /m 3 for drywall, 0.20‐0.28 m 2 /m 3 for wood, and 0.27‐0.36 m 2 /m 3 for carpet.…”

Section: Indoor Watermentioning

confidence: 99%

“…Two surveys of indoor surface materials important for moisture uptake and humidity buffering were mentioned in Section 2.4 33,48 . In addition to surface‐to‐volume ratios, Hodgson et al 23 and Manuja et al 25 cataloged the different materials that constituted the surfaces in their surveyed environments.…”

Section: Surfaces and Substratesmentioning

confidence: 99%

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Indoor acids and bases

2020

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Numerous acids and bases influence indoor air quality. The most abundant of these species are CO2 (acidic) and NH3 (basic), both emitted by building occupants. Other prominent inorganic acids are HNO3, HONO, SO2, H2SO4, HCl, and HOCl. Prominent organic acids include formic, acetic, and lactic; nicotine is a noteworthy organic base. Sources of N‐, S‐, and Cl‐containing acids can include ventilation from outdoors, indoor combustion, consumer product use, and chemical reactions. Organic acids are commonly more abundant indoors than outdoors, with indoor sources including occupants, wood, and cooking. Beyond NH3 and nicotine, other noteworthy bases include inorganic and organic amines. Acids and bases partition indoors among the gas‐phase, airborne particles, bulk water, and surfaces; relevant thermodynamic parameters governing the partitioning are the acid‐dissociation constant (Ka), Henry's law constant (KH), and the octanol‐air partition coefficient (Koa). Condensed‐phase water strongly influences the fate of indoor acids and bases and is also a medium for chemical interactions. Indoor surfaces can be large reservoirs of acids and bases. This extensive review of the state of knowledge establishes a foundation for future inquiry to better understand how acids and bases influence the suitability of indoor environments for occupants, cultural artifacts, and sensitive equipment.

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Section: Indoor Watermentioning

confidence: 99%

Section: Indoor Watermentioning

confidence: 99%

Section: Indoor Watermentioning

confidence: 99%

Section: Surfaces and Substratesmentioning

confidence: 99%

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Indoor acids and bases

2020

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“…The two curves overlap quite well, though the theoretical values are generally larger, especially during occupation hours. One explanation could be moisture buffering, that is, building materials and furniture absorb and release moisture, thus lowering the measured RH (see, for example, Osanyintola and Simonson, 2006; Woods and Winkler, 2018).…”

Section: Resultsmentioning

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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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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