scholarly journals Hygrothermal Monitoring of Two Pilot Prefabricated Exterior Energy Retrofit Panel Designs

2021 ◽  
Vol 2069 (1) ◽  
pp. 012028
Author(s):  
B Conley ◽  
M Carver ◽  
S Brideau
Keyword(s):  
Moisture Content ◽  
Oriented Strand Board ◽  
Significant Risk ◽  
Expanded Polystyrene ◽  
Mould Growth ◽  
Energy Retrofit ◽  
Fibrous Insulation ◽  
And Performance ◽  
Dry Out ◽  
Small Building

Abstract NRCan undertook a proof-of-concept project to retrofit a small building with prefabricated wall panels in 2017 in Ottawa, Canada. The retrofit used two wall panel designs: nailbase and woodframe. The Nailbase panel consisted of fiberglass batt, an expanded polystyrene (EPS) core, oriented strand board (OSB) sheathing, a rainscreen, and cladding. The Woodframe panel also featured OSB sheathing and included a 90 mm stand-off gap filled with dense-packed, fibrous insulation. A side-by-side comparison of cost, constructability, and performance was performed. The wall assemblies were instrumented to monitor the temperature, relative humidity, and moisture content of sensitive layers. The data was used to evaluate the hygrothermal performance, moisture accumulation, and risk of associated problems such as mould growth. This paper presents the monitored hygrothermal data from 2017 to 2021, compares the two approaches and assesses their feasibility. During construction, some of the fibrous insulation may have been wetted by wind-driven snow before completion. The data showed that this moisture was able to dissipate without significant risk. The sheathing of the Woodframe panel experienced a higher peak moisture content during the dry-out period. Otherwise, both panel designs showed limited potential for mould growth on monitored surfaces over the monitored period.

CLT construction without weather protection requires extensive moisture control

2021 ◽  
pp. 174425912199638
Author(s):  
Lars Olsson
Keyword(s):  
Moisture Content ◽  
Field Measurements ◽  
Scientific Work ◽  
Field Studies ◽  
Microbiological Analysis ◽  
Mould Growth ◽  
Extensive Growth ◽  
Almost All ◽  
Dry Out ◽  
Moisture Conditions

This study examines how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are affected by precipitation during construction. The case studies are based on moisture content measurements and material sampling as well as microbiological analysis during the structure’s construction stage. The study does not include remediation control. The field measurements show microbiological growth in all buildings and almost all floor structures that were investigated. Of a total of 200 measuring points analysed, half had mould growth and around a third had moderate or extensive growth. The moisture content measurements for one of the locations with the largest percentage of elevated or high moisture content was at the top of the floor structure in the bottom gap between timbers in the CLT top layer. This is one example of several materials or construction components where there is limited possibility of dry out. Based on the outcome, it would appear difficult, or impossible, to avoid the appearance of microbial growth during construction with CLT without weather protection. Previous studies indicate that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which implies that there are obvious shortcomings in the scientific work. The fact that mould growth is often invisible needs to be disseminated, especially in practical studies. However, there seems to be a good level of awareness in the literature that theoretical studies often conduct mould growth risk evaluations. There do not appear to be any moisture safety assembly methods or solutions for CLT construction that do not have weather protection or a declaration of the critical moisture conditions for CLT products.

Optimal Control of a General Environmental Space

1986 ◽  
Vol 108 (4) ◽  
pp. 330-339 ◽  
Author(s):  
M. A. Townsend ◽  
D. B. Cherchas ◽  
A. Abdelmessih
Keyword(s):  
Optimal Control ◽  
Maximum Principle ◽  
Moisture Content ◽  
Control Strategies ◽  
Switching Control ◽  
The Maximum Principle ◽  
Environmental Space ◽  
And Performance

This study considers the optimal control of dry bulb temperature and moisture content in a single zone, to be accomplished in such a way as to be implementable in any zone of a multi-zone system. Optimality is determined in terms of appropriate cost and performance functions and subject to practical limits using the maximum principle. Several candidate optimal control strategies are investigated. It is shown that a bang-bang switching control which is theoretically periodic is a least cost practical control. In addition, specific attributes of this class of problem are explored.

scholarly journals Performance of Oriented Strand Board Made with Soy Substituted Resin in Termite Choice Tests with Southern Yellow Pine

2021 ◽  
Vol 71 (3) ◽  
pp. 199-208
Author(s):  
Qingzheng Cheng ◽  
Juliet D. Tang ◽  
Chengfeng Zhou ◽  
Wei Jiang ◽  
Lixia Hu ◽  
...  
Keyword(s):  
Weight Loss ◽  
Moisture Content ◽  
Oriented Strand Board ◽  
Soy Flour ◽  
Water Repellent ◽  
Rating Data ◽  
Structural Applications ◽  
Choice Tests ◽  
Yellow Pine ◽  
Southern Yellow Pine

Abstract Soy flour was evaluated as a partial substitute for resin in the manufacture of oriented strand board (OSB), a wood-based composite that often replaces solid lumber and plywood in structural applications in the construction industry. Since the presence of soy could alter OSB biodegradation properties, termite resistance of OSB panels made with 0, 10, and 20 percent of polymeric methylene diphenyl diisocyanate (pMDI) resin substituted with soy flour (OSB0, OSB10, and OSB20, respectively) was investigated. Single choice tests between three types of OSB and southern yellow pine (SYP) solid wood and an OSB choice test (OSB0 vs. OSB10) were evaluated. Results indicated that termites always showed a preference for SYP, with the OSB becoming less palatable when soy flour was present. Percentage weight losses for OSB0, OSB10, and OSB20 were 5.7×, 8.4×, and 8.6× less, respectively, compared with SYP. In the absence of SYP, termites did not differentiate OSB0 from OSB10, with OSB10 showing 1.5× less weight loss compared with OSB0. Visual rating data supported weight loss data, except significantly less damage was only found when the choice paired SYP with OSB made with soy (OSB10 or OSB20). Termite consumption preference for SYP was explained by differences in water absorption kinetics. SYP reached saturation (105% moisture content) within 1 week on moist sand, while moisture content of OSB composites slowly climbed to 79 percent over 4 weeks, never reaching a plateau. Lower moisture content was due to the presence of water-repellent resin and wax in the OSB.

Efficient Eco-friendly Composite Fluorine Anhydrite-Based Materials

2017 ◽  
Author(s):  
Grigory Yakovlev ◽  
Jadvyga Keriene ◽  
Anastasiia Gordina ◽  
Irina Polyanskikh ◽  
Milan Bekmansurov
Keyword(s):  
Water Absorption ◽  
Lightweight Concrete ◽  
Gas Permeability ◽  
Average Density ◽  
Expanded Polystyrene ◽  
Environmental Load ◽  
Great Demand ◽  
Technogenic Waste ◽  
And Performance ◽  
Reduced Water

The paper presents possible ways of utilizing technogenic waste – fluorine anhydrite – by its use in production of dry mortars and piece goods from lightweight concrete with expanded polystyrene, as a organic filler, for low-rise construc-tion. The developed dry mortars are based on fluorine anhydrite binder and complex modifier comprising curing activator (sulfate or alkaline) and finely dispersed additive. The fluorine anhydrite-based compositions have improved physical and performance characteristics, including the improved strength and average density and reduced water absorption compared to the control composition. The developed lightweight anhydrite polystyrene concrete has the density grade of 700 kg/m3 and good vapor and gas permeability. The concrete is stabile while using and fire safe, because each granule of expanded poly-styrene is coated with anhydrite matrix, and has the strength sufficient for structural and heat insulating slabs and blocks. All mentioned compositions are eco-friendly and are in great demand for low-rise construction. Therefore the manufacturing of these compositions will consume a large amount of technogenic waste and will reduce the environmental load on the region where the waste is located.

Influence of the initial moisture content on the carbonation degree and performance of fiber-cement composites

2019 ◽  
Vol 215 ◽  
pp. 22-29 ◽  
Author(s):  
Gustavo Henrique Denzin Tonoli ◽  
Guilherme Fernando Carmello ◽  
Carlos Alexandre Fioroni ◽  
Tiago de Lima Pereira ◽  
Gustavo Rocha ◽  
...  
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Cement Composites ◽  
And Performance

Influence of interior layer properties to moisture dry-out of CLT walls

2019 ◽  
Vol 46 (11) ◽  
pp. 1001-1009 ◽  
Author(s):  
Villu Kukk ◽  
Annegrete Külaots ◽  
Jaan Kers ◽  
Targo Kalamees
Keyword(s):  
Moisture Content ◽  
Laboratory Test ◽  
Simulation Model ◽  
Initial Moisture Content ◽  
Mineral Wool ◽  
Test Results ◽  
Interior Layer ◽  
Cross Laminated Timber ◽  
Simulation Results ◽  
Dry Out

The objective of this study was to determine the maximum allowable initial moisture content (MC) for cross-laminated timber (CLT) walls having both exterior and interior thermal insulation. A laboratory test was conducted, for which four test walls with two different insulation solutions and two different MCs were built. Based on the test results, a simulation model was configured and simulations using the model were completed. The simulation results determined that the maximum allowable initial MC of the CLT panels was 17% for walls insulated additionally from inside with mineral wool and 15% for CLT wall assemblies insulated with polyisocyanurate (PIR). Based on these results, it was concluded that the allowable MC ranges between 8% and 16% for construction timber, and therefore, using a PIR board as interior insulation for CLT walls should be undertaken with caution given the very small margin for error in MC.

scholarly journals Assessment of quality defects in macadamia kernels using NIR spectroscopy

2004 ◽  
Vol 55 (4) ◽  
pp. 471 ◽  
Author(s):  
John Guthrie ◽  
Colin Greensill ◽  
Ray Bowden ◽  
Kerry Walsh
Keyword(s):  
Moisture Content ◽  
Oil Content ◽  
Model Performance ◽  
Nir Spectroscopy ◽  
Principal Component ◽  
Insect Damage ◽  
Mould Growth ◽  
Reference Analysis ◽  
Calibration Models ◽  
Calibration Coefficients

Spectral data were collected of intact and ground kernels using 3 instruments (using Si-PbS, Si, and InGaAs detectors), operating over different areas of the spectrum (between 400 and 2500 nm) and employing transmittance, interactance, and reflectance sample presentation strategies. Kernels were assessed on the basis of oil and water content, and with respect to the defect categories of insect damage, rancidity, discoloration, mould growth, germination, and decomposition. Predictive model performance statistics for oil content models were acceptable on all instruments (R2 > 0.98; RMSECV < 2.5%, which is similar to reference analysis error), although that for the instrument employing reflectance optics was inferior to models developed for the instruments employing transmission optics. The spectral positions for calibration coefficients were consistent with absorbance due to the third overtones of CH2 stretching. Calibration models for moisture content in ground samples were acceptable on all instruments (R2 > 0.97; RMSECV < 0.2%), whereas calibration models for intact kernels were relatively poor. Calibration coefficients were more highly weighted around 1360, 740 and 840 nm, consistent with absorbance due to overtones of O-H stretching and combination. Intact kernels with brown centres or rancidity could be discriminated from each other and from sound kernels using principal component analysis. Part kernels affected by insect damage, discoloration, mould growth, germination, and decomposition could be discriminated from sound kernels. However, discrimination among these defect categories was not distinct and could not be validated on an independent set.It is concluded that there is good potential for a low cost Si photodiode array instrument to be employed to identify some quality defects of intact macadamia kernels and to quantify oil and moisture content of kernels in the process laboratory and for oil content in-line. Further work is required to examine the robustness of predictive models across different populations, including growing districts, cultivars and times of harvest.

Adhesives from Waste Protein Biomass for Oriented Strand Board Composites: Development and Performance

2014 ◽  
Vol 299 (8) ◽  
pp. 1003-1012 ◽  
Author(s):  
Tizazu H. Mekonnen ◽  
Paolo G. Mussone ◽  
Phillip Choi ◽  
David C. Bressler
Keyword(s):  
Oriented Strand Board ◽  
And Performance

scholarly journals THE EFFECT OF MOISTURE CONTENT OF FORAGE STORED IN POLYVINYL SILOS ON INTAKE AND PERFORMANCE OF DAIRY COWS

1964 ◽  
Vol 44 (2) ◽  
pp. 125-131 ◽  
Author(s):  
V. S. Logan ◽  
P. S. Haydon
Keyword(s):  
Moisture Content ◽  
Dry Matter ◽  
Milk Composition ◽  
Matter Content ◽  
Dry Matter Intake ◽  
Dry Matter Content ◽  
Forage Intake ◽  
Silage Quality ◽  
And Performance ◽  
Gas Tight

Legume–grass forage was ensiled two seasons in 25-ton polyvinyl-encased stacks at dry matter (D.M.) levels of 22 to 37% or stored as field-cured hay. The polyvinyl sleeve coverings provided initial gas-tight conditions. High losses occurred in the high D.M. (32 to 37%) silage during the feeding-out period. Silage quality, as indicated by volatile fatty acid ratios, proximate principles, and digestibility coefficients, was not significantly influenced by D.M. content. When cows were fed the lower D.M. (22 to 29%) silages and hay, forage intake was inversely related to its dry matter content. Intake of high D.M. silage appeared abnormally low. Milk yields appeared to be more consistently influenced by small variations in grain intake than forage dry matter intake through both trials. Milk yields from silages were greater than from hay per unit of D.M. intake. Moisture content of forage had no significant effect on milk composition as indicated by percentage of butterfat, solids-not-fat, or protein.

scholarly journals Development and performance evaluation of a solar tunnel date dryer in Oman

2012 ◽  
Vol 17 ◽  
pp. 21
Author(s):  
Mohammad Ali Basunia ◽  
Hamid H. Al-Handali ◽  
Mohammed Issa Al-Belushi ◽  
Mohammad Shafiur Rahman ◽  
Osman Maghoub
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Average Moisture Content ◽  
Air Velocity ◽  
Sun Drying ◽  
Tunnel Dryer ◽  
Moisture Content Level ◽  
Collector Region ◽  
And Performance

Taking into consideration the date harvesting and landholding capacities of the marginalized rural farmers in Oman, a 12 meter long and 2 meter wide tunnel was designed and constructed to dry about 180-200 kg of freshly harvested dates per batch. Half of the tunnel base was used as a flat plate air heating solar collector and the other half as a dryer. The drying air was forced from the collector region (South side) to the drying region (North side) of the half circled tunnel where the product is to be dried. The drying temperature could be easily raised by some 5-30 oC above the ambient temperature inside the tunnel at an air velocity of approximately 0.5 m/sec. The test was conducted with 190.2 kg freshly harvested dates with initial moisture content of 32.8% (wet-basis) to analyze the performance of the dryer. The dates were dried to a final average moisture content of 18.6% (wet-basis) within two days (20 hours). The results indicated that the drying was faster in a solar tunnel dryer than the natural open air sun drying. It was possible to reach the moisture content level for safe storage within less than two days (20 hrs) with a solar tunnel dryer and 5-7 days in open air natural sun drying. The improvement in the quality of dates in terms of color and brightness was distinctly recognized. 

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