Adapting rain data for hygrothermal models

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis 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. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.buildenv.2008.07.002 Building and environment, 30, pp. 1-10, 2008-10-20 Adapting rain data for hygrothermal modeling Cornick, S. M.; Dalgliesh, A.http://irc.nrc-cnrc.gc.ca Adapting rain data for hygrothermal modeling NRCC-50832Cornick, S.M.; Dalgliesh, A. 2008-10-01A version of this document is published in / Une version de ce document se trouve dans: Building and environment, v. 30, 2008 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-42Les 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 AbstractDesign for moisture control has now become an established part of building envelope design. Hygrothermal modeling tools, capable of simulating moisture transfer in materials, are a key element of the design process. There are three principle methods of moisture transfer in envelopes. They are, in order of magnitude, capillary action, vapour convection, and vapour diffusion. Wind-driven rain has the potential to deposit large amounts of liquid water on the exterior surface, as well inside walls through rain penetration, providing a significant source for moisture transport.

Sensitivity of Hygrothermal Analysis to Uncertainty in Rain Data

“…The 20 % amount generally bounds the error between the tipping bucket and estimated rainfall data, or both, and the climate normal data 3 . Variations of the observation codes consist of varying the recommended intensities in order to minimize the error between the estimated long-term means and measured long-term means [15]. The variations are summarized in TABLE 3.…”

“…Rainfall intensities for the weather observation codes were determined from the values recommended by Environment Canada [26] [27]. Cornick and Dalgliesh [15] discuss in detail the conversion of weather observation codes to hourly rainfall intensities. Variations on both these base years consist of increasing and decreasing the rainfall intensities by 20 %.…”

“…Perhaps the next most important parameter to examine is the weather data. Weather data used as input for hygrothermal modeling purposes is generally assumed to be reliable, but recent work has shown that there may be considerable uncertainty in the rainfall data [15]. Several comprehensive studies by Blocken and Carmeliet [16][17] [18] [19] have examined uncertainties in wind-driven rain calculations.…”

“…There is a wealth of scientific literature on estimating rainfall from sparse data; however, most of the work is related to hydrology or agriculture [21] [22]. Koronthályová and Matiašovský [23] published a method for generating hourly wind-driven rain amount values from daily courses of driving-rain and Cornick and Dalgliesh [15] examined various methods for converting qualitative rain observations to quantitative values. In that work various methods for fully populating datasets of qualitative data, such as "light rain," with quantitative hourly rainfall intensities were examined.…”

“…Each location has at least 30 years of rainfall intensity data (except the near arctic location). In terms of variations the rain gauge data were assumed to be correct although too much faith should not be placed in this assumption [15]. Several performance measures were used to assess the responses to the different rain inputs: the total moisture content, a mould index, and a time-of-wetness indicator.…”