b'BACK TO BASICS FIGURE 3: PROBLEMATIC INSTALLATION DESIGN DETAIL FIGURE 4: CONDENSATION CASE STUDYSILL DETAILbreak and appeared to be installedcompared the method to infrared measure- seven different suggestions that I wont reasonably well according to the designment of condensation potential and showeddescribe here (because a good conjurer intent (Figure 4). A site visit showed thatgood agreement to the measured results.never reveals all the tricks), but by way of condensate formed and accumulated onThe method was briefly included in the CSAexample, the owners rejected heat-tracing the frame (Figure 5), so an investigationA440 Standard, Windows, until manufac- because they didnt want to plug their was required. turers voted it outa longer story than wewindows into the wall to fix the conden-I modelled the window using the FRAMEhave space for here. sation problem.program (Figure 6). The methodology forThe simulation results werent matching theThe developer didnt want to remove and modelling condensation in windows, toobserved condition shown in Figure 5, soreinstall all the windows, so a compro-include the mechanisms shown in FigureI asked the architect for more informationmise solution was to repair the thermal 2, is described in a paper I wrote withabout the installation details. He providedbridge in situ. This involved removing the Professor John Wright from the University of Waterloo1. That paper discussed oura photograph of a sill pan that was installedsill cover to expose the back leg of the sill procedure and compared it to physical teststo promote drainage. Unfortunately, the sillpan (Figure 9), then cutting out the back for condensation potential, as measuredpan went right to the back of the sub-sill arealeg of the sill pan and moving the window using thermocouples. A follow-up paper2(Figure 7, pg. 19), thus bypassing the thermalshims above the sill pan. This would break. When I revised the FRAME model toseparate the metal pan from the window 1 McGowan, A.G., and J.L. Wright, 1998.represent the as-installed condition (Figure 8,frame, thus decoupling the thermal Computer Simulation of Windowpg. 19), the predicted temperature at thebridge from the interior extrusion of the Condensation Potential, Proceedings of the Thermal Performance of the Exteriorinside corner of the frame to 5.1 C, whichwindow frame. The cavity between the sill Envelopes of Buildings VII, Clearwater,matched what I had measured on site topan and the window frame, which would Florida, available at https://web.ornl.gov/ within about 1 C. be open to the outdoors, would then be sci/buildings/conf-archive/index.shtm. filled with foam insulation or thin pieces 2 Wright, J.L. and A.G. McGowan, 2003. AUsing this validated model, I couldof EPS or XPS, and the back of the sill pan Comparison of Calculated and Measuredthen use simulation to evaluate variousopening would be replaced with sealant Indoor-Side Window Temperature Profiles, ASHRAE Transactions vol. 109, part 2. options for remediation. I came up withto prevent water ingress.FIGURE 5: CONDENSATE ON FRAME, BUT NOT ON GLASS FIGURE 6: COMPUTER MODEL OF THE ASSEMBLY18 BCBEC ELEMENTSA BCBEC PUBLICATION'