Report from Task 4 of MEWS Project - Task 4-Environmental Conditions Final Report

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TypeTechnical Report
Series titleResearch Report, NRC Institute for Research in Construction; Volume 113
Physical description110 p.
SubjectMoisture performance
AbstractTask 4 - Environmental Conditions consisted of two main objectives: the first objective was to provide input for the parametric simulation phase of Task 7- Hygrothermal Analysis and the rain penetration test portion of Task 6 - System Performance; the second objective was to develop a method for classifying for US and Canadian climates with respect to moisture loading. Hourly weather data for approximately 400 Canadian and US locations were collected. The data spans 30 or more years. A list of 40 candidate cities was created from the locations available. Data for the 40 cities, 27 American and 13 Canadian, were analyzed and converted into the appropriate format for the Advanced Hygrothermal Model (AHM). A method for calculating a moisture index based on two independent indices, the wetting index and the drying index was developed characterize the locations in the 40 city set. From the candidate list five cities were selected: Wilmington NC, Seattle WA, Ottawa ON, Winnipeg MB, and Phoenix AZ for detailed analysis. Reference years to be input to the AHM as part of the parametric study were determined for each of the five cities selected for detailed analysis. A modified method for calculating the moisture index cities was used to select reference years. The modified method included the effect of wind-driven rain and the effect of orientation. For selecting reference years the definition of the wetting index included the direction of predominantrainfall. A wet year, a dry year, and an average year were defined as reference years for each of the five selected cities. Finally, five methods of calculating wind driven rain were reviewed and found to be ingeneral agreement. Experimental results confirm the validity of the methods reviewed. Straube's method for calculating the amount of wind driven rain impinging on a wall was selected for use. It was chosen because it is generally the most conservative of the methods considered and was also the method selected for incorporation into the AHM. Two spray rates, 100 L/m 2 -h (1.7 L/min-m 2 ) and 200 L/m 2 -h (3.4 L/min-m 2 ) and a maximum pressure level of 700 Pa +/- 300 Pa cycled at 0.5 Hz were determined from the literature and climate data. These recommendations were used in the rain penetration portion of Task 6. The second objective was to develop a method for classifying climates with respect to moisture loading. Climates were classified using a similar method used to classify the 40 candidate cities. Climates were classified according to their potential for moisture loading. Five groups were defined: Zone 1, Zone 2, Zone 3, Zone 4, and Zone 5. A provisional contour map showing isopotentials for Canada and the United States was created.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedNo
NRC number15123
NPARC number20378857
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Record identifiercf5e2368-ad90-48a3-8efa-92ad101de414
Record created2012-07-24
Record modified2016-10-03
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