Publisher’s version / Version de l'éditeur:
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
Building Physics Symposium [Proceedings], pp. 1-4, 2008-10-29
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright
NRC Publications Archive Record / Notice des Archives des publications du CNRC :
https://nrc-publications.canada.ca/eng/view/object/?id=e4f1e7ed-6662-43d4-81d7-a31e3c78c4a5 https://publications-cnrc.canada.ca/fra/voir/objet/?id=e4f1e7ed-6662-43d4-81d7-a31e3c78c4a5
NRC Publications Archive
Archives des publications du CNRC
This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at
Benchmarking hygrothermal tools with full-scale laboratory drying
experiments
http://irc.nrc-cnrc.gc.ca
B e n c h m a r k i n g h y d r o t h e r m a l t o o l s w i t h f u l l - s c a l e
l a b o r a t o r y d r y i n g e x p e r i m e n t s
N R C C - 5 0 8 1 2
M a r e f , W .
2 0 0 8 - 1 1 - 0 6
A version of this document is published in / Une version de ce document se trouve dans:
Building Physics Symposium, Leuven, Belgium, Oct. 29-31, 2008, pp. 1-4
The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42
Les renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42
Benchmarking Hygrothermal Tools with Full-Scale Laboratory
Drying Experiments
Wahid Maref
National Research Council Canada-Institute for Research in Construction (NRCC-IRC) 1200 Montreal Road Campus, Building M-24
Ottawa, Ontario K1A 0R6 Canada Tel. 1-613-993 5709; Wahid.maref@nrc-cnrc.gc.ca
Keywords: Hygrothermal, Drying, Laboratory, Moisture, Performance, Experiments, Modelling.
Abstract: The hygrothermal performance of building envelope system is dictated by the response of the system to combined heat, air and moisture fluctuations produced by exterior and interior conditions that exist on either side of the envelope. This study was undertaken to generate information that would assist the benchmarking of a hygrothermal simulation model and related methods to assess hygrothermal performance of wall assemblies. This paper presents a series of drying experiments on oriented strand board (OSB) alone or in combination with different sheathing membranes designed to benchmark the hygrothermal simulation model called “hygIRC”. It also presents preliminary results from a series of simulations in which the shape of the drying curve and the time taken to establish the equilibrium moisture content are determined and compared with the experimental results. This was one of several steps undertaken in a broader benchmarking exercise to validate the model and its implementation.
1.1 Objectives
The objectives of this study was to determine the minimum characteristics and level of performance of various wall assemblies and components in handling rainwater ingress on the surface of the walls by:
• Measuring the overall hygrothermal behaviour of wood-based materials in wood-frame construction when subjected to steady state and transient boundary conditions, and
• Validating hygIRC, used to assess the drying rate of wood-based components.
1.2 hygIRC – Advanced hygrothermal model
The development and application of NRC-IRC’s advanced hygrothermal model hygIRC have been previously reported by Maref et al1,2. hygIRC is an enhanced version of LATENITE3-7, to which has recently been added knowledge related to quantifying wind-driven rain on building facades8. This work permitted predicting liquid water moisture loads on exterior wall surfaces. Extensive laboratory and analytical benchmarking exercises of the model hygIRC were completed at the system level9-11 as well as in a field benchmarking exercise12.
1.3 Experimental approach
To achieve the above objectives, several series of drying experiments were carried out in controlled laboratory conditions on full-scale sheathing boards having nominal dimensions of 2.43 by 2.43-m. As well, in order to verify experimental results and develop a basis for validation of hygIRC, extensive use of the model was made. The full-scale tests were conducted in a series of steps, each step comprised of evaluating the hygrothermal response of a full-scale specimen to specified laboratory controlled conditions. The initial step consisted of determining the response of a single sheet of oriented strand board (OSB) to specified conditions whereas each subsequent step had an increased level of complexity in regard to the number of assembly components being modeled and for which data was to be reconciled with the experiment. This step-wise approach permitted gaining a better understanding of the relative contribution of each component to key hygrothermal effects. In this way,
complex assemblies of components were analyzed and their hygrothermal response to steady or transient state climatic conditions characterized in relation to that simulated using hygIRC.
1.3.1 Full-scale wall specimens
A brief description of the one experimental set is provided in this section. This set consisted of evaluating the hygrothermal properties of a single sheet of OSB that was de-coupled from the wood-frame assembly, this being achieved by coating the wood-wood-frame with a lacquer and thus essentially rendering the frame resistant to moisture uptake. A sheathing membrane was installed on the OSB, fiberglass insulation was added into the stud cavities and a single sheet of polyethylene was installed on the opposite side of the assembly.
1.3.2 Pre-conditioning
Full-scale specimens were also pre-conditioned to insure that the OSB sheathing boards were brought to elevated moisture contents. The pre-conditioning consisted of two phases: immersion and stabilisation. The immersion phase permitted the OSB to quickly reach an elevated level of moisture content. The stabilisation phase insured that the moisture content throughout the component reached equilibrium.
2. NOMINAL RESULTS FROM BENCHMARKING EXERCISES
Results on one experiment of this series are presented in this paper. Figure 1 shows a comparison between simulated and total measured MC of OSB derived from experimental results. The initial total MC for both boards in the assembly is about 51 %. After 33 days a value of 16% MC is attained. These results indicate a very good agreement between the results obtained from simulation and those derived from experiment. In fact, the greatest difference between the simulated and the experimental results after 33 days is not more than 1.4 % MC.
0% 10% 20% 30% 40% 50% 60% 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Time (Days) Tota l Mois ture Conte nt (k gw / k gd) Experiment Simulation
Fig. 1— Comparison of experiment and simulated drying results in terms of total MC (%) of OSB sheathing wall components
In these experiments, local moisture content was measured using electrical resistance measurements at moisture pin pairs. These were installed in the OSB at different locations and at different depths. The resistance measurements taken across each pair of moisture pins were continuously monitored and results captured on a data acquisition unit. Moisture contents at a given pin-pair location were determined by associating the resistance to a specific moisture content based on the resistance-MC calibration curve obtained from other experiments13. Figure 2 shows the wall specimen and the location of each moisture pin sensor. The moisture pins were installed in six specific zones, each zone representative of the size of specimen used in the mid-scale tests (i.e. 0.8-m by 1-m). The MC data retrieved from each zone provides the basic information needed to map the MC distribution over the entire wall.
Fig. 2 - Moisture pin locations 1 2 3 4 5 6 10 9 8 7 11 12 13 14 15 19 18 17 16 20 21 22 23 24 25 26 27 28 29 30 31 32
Figure 3 shows the change in resistance (MΏ) in relation to time (days) in zone 3 of the OSB sheathing for each 7 moisture pin pairs installed at one half the specimen depth. The drying appears to be very rapid; after 10 days the resistance values across moisture pin sensors are between 80 MΩ and 700 MΩ for all specimens. In another words, the MC in this wall zone is between 12.7 % and 10 % MC. Figure 4 provides a similar response to that apparent from the results given in Figure 3. It shows the drying curve for the OSB in Zone 1 of the panel in terms of change in MC over time. In Zone 1, it is apparent that the moisture pins located at the top are first to indicate drying whereas those located at the bottom follow after this process is initiated. This indicates that the bottom has a tendency to stay wet while the top dries out.
0 100 200 300 400 500 600 700 800 900 0 2 4 6 8 10 12 14 16 18 20 22 Time (Days) Resi stan ce (MOhm s ) MP 20 MP 9 MP 7 MP 15 MP 21 MP 19 MP 8 1 2 3 4 5 6 10 9 8 7 11 12 13 14 15 19 18 17 16 20 21 22 23 24 25 26 27 28 29 30 31 32 2.43 m 2.43 m 0% 5% 10% 15% 20% 25% 30% 35% 0 2 4 6 8 10 12 14 16 18 20 22 Time (Days) Mois tur e C onte n t (% ) 1 2 3 4 5 6 10 9 8 7 11 12 13 14 15 19 18 17 16 20 21 22 23 24 25 26 27 28 29 30 31 32 2.43 m 2.43 m MP 7 MP 15 MP 8 MP 9 MP 20 MP 21 MP 19
Fig. 3 - Resistance versus time of the 7 moisture pins in zone 3
Figure 4 – Moisture content versus time of the 7 moisture pins in zone 3.
3. CONCLUDING REMARKS
The results presented in this paper offer an overview of the work carried out on full-scale drying experiments. The most apparent observation is that the moisture pins provide quantitative information on the moisture content of the OSB in each zone over the time the drying experiment is conducted. The hygrothermal simulation model hygIRC has been used in various other studies as the primarily analytical tool to conduct a parametric study to assess the hygrothermal performance of various wall assembly types subjected to different North American climatic conditions14. It has been demonstrated that the overall agreement between the experimental and simulated drying curves is excellent in terms of the time to reach equilibrium moisture content, as well as the shape of the drying curve derived from these experimental sets. As has been demonstrated from comparison of results obtained from simulation to that of controlled laboratory experiments, hygIRC can adequately duplicate the response of the modeled assemblies and thus help predict hygrothermal behaviour of wall components when subjecting the components to simulated climatic conditions.
REFERENCES
. Kumaran, M.A. Lacasse, M.C. Swinton, D. van Reenen, D. (2002), "Laboratory nd benchmarking of an advanced hygrothermal model," Proceedings of the 12th
odel-hygIRC with mid-scale experiments," eSim 2002 Proceedings (University of
94
nvelopes of
ng R&D Workshop, pp. III-25 to III-36, 1998, Sapporo, Japan,
n, PA, 1994, pp. 18-34
uildings and Community Systems, Annex 24, Heat, Air and
the Exterior Envelopes of
heathing and combined membrane
Construction,
Shamir, D., Assessment Method of
nal Building Physics /Engineering Conference, August
bration Curve of OSB Using Moisture Pins, Submitted to: 2
Maref, P. Mukhopadhyaya, M. Nofal, N. Normandin, M. Nicholls, T. O'Connor; [1] W. Maref; M.K
measurements a
International Heat Transfer Conference (Grenoble, France, August 18, 2002), pp. 117-122, October 01, 2002 (NRCC-43054)
[2] W. Maref, M.A. Lacasse, M.K. Kumaran, M.C. Swinton,. (2002), "Benchmarking of the advanced hygrothermal m
Concordia, Montreal, September 12, 2002), pp. 171-176, October 01, 2002 (NRCC-43970)
[3] M. Salonvaara and A.N. Karagiozis (1994), Moisture Transport in Building Envelopes using an Approximate Factorization Solution Method, CFD Society of Canada, Toronto, June 1-3, 19
[4] A.N. Karagiozis, M.H. Salonvaara and M.K. Kumaran (1995), The Effect of Waterproof Coating on Hygrothermal Performance of High-rise Wall Structure, Thermal Performance of the Exterior E
Buildings VI, Clearwater, FL (USA), 1995
[5] A. N. Karagiozis and M.K. Kumaran (1997), Applications of Hygrothermal Models to Building Envelope Design Guidelines, 4th Canada/Japan Housi
Nov. 16-21, 1997
[6] Moisture Control in Buildings, ASTM Manual Series MNL-18, American Society for Testing and Materials, West Conshohocke
[7] H. Hens, (1996), Final report Task 1. Modeling and Common Exercises, Summary reports. International Energy Agency, Energy Conservation in B
Moisture Transport in New and Retrofitted Building Envelope Parts (HAMTIE).
[8] F. Tariku, S.M. Cornick, M.A. Lacasse, (2007), Simulation of Wind-Driven Rain Effects on the Performance of a Stucco-Clad Wall, Proceedings of Thermal Performance of
Whole Buildings X, International Conference, Dec. 2-7, Clearwater, FL
[9] W. Maref, M.A. Lacasse, D.G. Booth, M. Nicholls and T. O'Connor, (2002), Automated weighing and moisture sensor system to assess the hygrothermal response of wood-s
sheathing wall components, 11th Symposium for Building Physics, Dresden, Germany, 2002.
[10] W. Maref, M.A. Lacasse, D.G. Booth (2002), Benchmarking of IRC's Advanced Hygrothermal Model - hygIRC Using Mid- and Large-Scale Experiments, Research Report, Institute for Research in
National Research Council Canada, 126, pp. 38, December 01, 2002
[11] C.E. Hagentoft, Adan, O.; Adl-Zarrabi, B.; Becker, R.; Brocken, H.; Carmeliet, J.; Djebbar, R.; Funk, M.; Grunewald, J.; Hens, H.; Kumaran, M.K.; Roels, S.; Kalagasidis, A.S.;
Numerical Prediction Models for Combined Heat, Air and Moisture Transfer in Building Components: Benchmarks for One-Dimensional Cases, pp. 26, July 22, 2003 (European Community Project HAMSTAD Technology Implementation Plan: Also published in Journal of Thermal Envelope and Building Science, v. 27, no. 4, April 2004, pp. 327-352) (NRCC-46623)
[12] F. Tariku, M.K. Kumaran, (2006), Hygrothermal Modeling of Aerated Concrete Wall and Comparison With Field Experiment, Proceedings of the 3rd Internatio
26-31, Montreal, Canada, pp. 321-328
[13] W. Maref and M.A. Lacasse, Experimental Assessment of Hygrothermal Properties of Wood-Frame Wall
Assemblies / Moisture Content Cali nd
Symposium on Heat-Air-Moisture Transport: Measurement and Implication in Buildings, April 19-20, 2009, Vancouver, B.C. Canada.
[14] P. Beaulieu; M.T. Bomberg, S.M. Cornick, W.A. Dalgliesh, G. Desmarais, R. Djebbar, M.K. Kumaran, M.A. Lacasse, J.C. Lackey, W.
J.D. Quirt, M.Z. Rousseau, M.N. Said, M.C. Swinton, F. Tariku, D. van Reenen, Final Report from Task 8 of MEWS Project (T8-03) - Hygrothermal Response of Exterior Wall Systems to Climate Loading: Methodology and Interpretation of Results for Stucco, EIFS, Masonry and Siding-Clad Wood-Frame Walls, Research Report, Institute for Research in Construction, National Research Council Canada, 118, pp. 1 v. (various pagings), November 01, 2002, (RR-118) URL: http://irc.nrc-cnrc.gc.ca/pubs/rr/rr118/.
