Calculating the Equilibrium Moisture Content for Wood Based on Humidity Measurements

Mitchell, Philip H.

doi:10.15376/biores.13.1.171-175

Cited by 12 publications

(11 citation statements)

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“…The EMC of this study was not measured directly, but derived from the model [30]. A lower bound for the modelled data was EMC, determined according to Mitchel [28], representing the EMC without rain influence, which was in good agreement with the modelled values whenever the level of precipitation was low during summer 2018 (Figure 9). Literature values report an average moisture content of unsheltered weathered wood in Sweden, mounted with an angle of 45 • , of 46% for pine sapwood and 25% for pine heartwood [32].…”

Section: Resultssupporting

confidence: 61%

“…The dew-point temperature of the air in the ventilation layer was determined according to Equations ( 1) and ( 2), and the partial water vapour pressure was determined using well-known relationships. The equilibrium moisture content of wood (EMC), on the basis of the relative moisture content of the surrounding air, was estimated according to Equation ( 3) [28].…”

Section: Methodsmentioning

confidence: 99%

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Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

Kain

Idam²,

Federspiel³

et al. 2020

Applied Sciences

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Wooden shingles are a traditional roofing material on many culturally important building artifacts. Currently, the roof space of many traditional buildings is used for residential purposes and, consequently, cold roof constructions with ventilation layers are applied. In this study, it is evaluated whether the moisture content of wooden shingles is adversely affected by such constructions, compared with unvented shingle roofs over cold attics and whether a temporary closing of the ventilation gaps at the eaves contributes to a lower wood moisture content. Various sensors were installed in and around a building with wooden shingles on a ventilated roof and temperature, air moisture, and air speed in the ventilation layer were measured throughout a year. The findings show that the air speed in the ventilation layer can be adjusted from 0.06 to 0.25 m/s depending on the layout of the eaves. A hygrothermal model was applied to evaluate the effects of different ventilation operation modes and cardinal orientations of the roof on the moisture content of the wooden shingles. The results show that roof ventilation results in a 1% lower shingle moisture content on average than an unventilated roof over a cold attic. Finally, it is shown that the wood moisture content repeatedly reaches dangerous levels above 25% throughout a year, which is worse on north-facing roofs and, hence, measures to increase the dry-out are relevant.

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Section: Resultssupporting

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

Kain

Idam²,

Federspiel³

et al. 2020

Applied Sciences

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“…Wie schon in [8] gezeigt werden konnte, hat die Temperatur nur einen geringen Einfluss auf die Holzausgleichsfeuchte. Dies betrifft die Auswertungsmethode nach [7] für den im Bauwesen relevanten Bereich (10 bis 30 °C), als auch die konstante Temperatur innerhalb der BSP-Wand.…”

Section: Danksagungunclassified

In situ‐Messung innerhalb einer Außenwand in Holz‐Massivbauweise mit Brettsperrholz im sockelnahen Bereich

Ganster

Schickhofer

2020

Bauphysik

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Der Feuchteschutz ist bei Konstruktionen aus Holz essentiell, um langfristige Schäden ausschließen zu können. Grundsätzlich hat die oder der Planende zwei Möglichkeiten, um Feuchteschäden zu verhindern. Zum einen ist das die bauphysikalische Strategie, bei der durch sinnvolle Wahl der Schichtenfolge, der Schichtdicken und der Materialien Bauteile so dimensioniert werden, dass die Wassergehalte in den maßgeblichen Schichten dauerhaft unterhalb einer zulässigen Grenze bleiben. Das Risiko solcher Feuchteeinträge wird typischerweise durch Berechnungen bzw. Simulationen durchgeführt. Zum anderen der konstruktive Holzschutz, der darauf abzielt, Feuchteeinflüsse durch bauliche Maßnahmen auszuschalten und sich dabei auf bewährte Detaillösungen verlässt. Die zunehmende Vielfalt an Detaillösungen und die wechselnden Anforderungen erschweren eine optimale Lösungsfindung, sei es im Bereich der Einfamilienhäuser oder im öffentlichen mehrgeschossigen Wohn‐ und Gewerbebau. Komfortwünsche seitens der Nutzer oder barrierefreies Bauen verlangen einen Niveauausgleich zwischen innerem Bodenbelag und äußerem Eingangsbereich. Daraus folgt, dass sich die eingebaute Fußschwelle der Außenwand nicht nur unter dem empfohlenen Maß, sondern auch unter dem Erdniveau befindet. Der vorliegende Aufsatz untersucht anhand einer zweijährigen In situ‐Messung die Holzfeuchtegehalte innerhalb einer Außenwand in Holz‐Massivbauweise mit Brettsperrholz im sockelnahen Bereich. Die Messsensoren wurden in den Einzelschichten sowie drei unterschiedlichen Höhen angeordnet. Die Ergebnisse zeigen vor allem an der kritischsten Messreihe eine erhöhte Holzausgleichsfeuchte.

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“…where, w (t) , is the mass of the wet material at instant t, d, is the mass of dry materials and w 0 , is the initial mass. Whereas, the equilibrium moisture was calculated according to [44].…”

Section: Drying Curvesmentioning

confidence: 99%

Improved Agricultural Products Drying Through a Novel Double Collector Solar Device

et al. 2019

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Backyard agricultural systems are frequently used for food production in rural tropical regions all over the world. The implementation of these systems has been used as a strategy to increase food security, to preserve the phyto and zoo diversity and to provide an alternative income for poorer rural families. Nevertheless, the absence of appropriate preservation mechanisms and nonrenewable energies can lead to significant production losses that could be prevented by the implementation of solar drying devices. The objective of this project was to design, build and validate a double collector solar device for improved drying performance. To evaluate the double collector solar device, four backyard products frequently used in the Mexico Southwest regional diet were used: carrots, chayote squash, tomatoes, and oyster mushrooms. The results showed that the solar device achieved drying efficiencies between 22.8 and 37.9% by reaching moisture values below the 12.30% threshold, which according to the international standards is considered as “Low Moisture Food”. The evaluation of the double collector solar drier is demonstrated to be an easy-to-apply and environmentally friendly method for food preservation in tropical rural regions by taking advantage of domestic renewable energy resources.

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Calculating the Equilibrium Moisture Content for Wood Based on Humidity Measurements

Cited by 12 publications

References 0 publications

Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

In situ‐Messung innerhalb einer Außenwand in Holz‐Massivbauweise mit Brettsperrholz im sockelnahen Bereich

Improved Agricultural Products Drying Through a Novel Double Collector Solar Device

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