Paper Conference

Proceedings of eSim 2010: 6th Conference of IBPSA-Canada

     

NUMERICAL SIMULATIONS FOR DETERMINING THE THERMAL RESPONSE OF WALL SYSTEMS WITH MEDIUM DENSITY POLYURETHANE SPRAY FOAMS

Tariku Tariku, W. Maref, M. C. Swinton, A. H. Elmahdy

Abstract: Using Polyurethane Spray Foams (SPFs) as insulation in buildings provide durable and efficient thermal barriers. The industry is encouraging the SPF as an effective air barrier system in addition to its thermal insulation characteristics. In an effort to address these issues, a consortium of SPF manufacturers and contractors, jointly with the National Research Council of Canada's Institute for Research in Construction, (NRC-IRC) conducted an extensive research project to assess the thermal and air leakage characteristics of SPF walls. Walls with glass fibre insulation and polyethylene air barrier were also considered as references. A number of walls with different types of SPFs and glass fibre were built and tested. Material characterization was also conducted to measure the thermal conductivities of a number of SPFs. Additionally, the thermal resistances (R-values) of these walls were measured using Guarded Hot Box (GHB) at two temperature differences across the walls (40 & 55 o C) and zero air leakage (i.e. pressure differences across the wall was 0). In order to investigate the effect of the air leakage on the R-values, however, air leakage tests were conducted for these walls at a wide range of pressure differences across the walls (25 Pa-170 Pa). The objective of this paper is to conduct 2D numerical simulations to determine the R-values with and without air leakage. These simulations were conducted using the advanced hygrothermal model that was developed by the NRC-IRC. The results showed that the model was successful in predicting the R-values with reasonably good agreements with the measured Rvalues using the GHB. After gaining confidence in predicting the R-values at no air leakage, a parametric study was conducted to predict the apparent R-values at two leakage rates that correspond to two pressure differences of 75 Pa and 150 Pa for each wall.
Pages: 185 - 192
Paper:
esim2010_7A1_185_192