b'PMRAheating season, offering a more realisticAs shown in Table 4, modelled reduc- reaches up to 25.7 per cent. These results assessment of how varying rain condi- tions in effective R-value across variousindicate that the negative thermal impact tionsinfluencethethermaltransmit- Canadian climate zones demonstrate aof rain is both climate-dependent and tance of each assembly over time. Usingclear correlation with annual precipita- seasonallyamplifiedinwetterregions. experimentallyderivedcorrelationstion levels. In Edmonton, which expe- However, when a water flow restricting between rain intensity and thermal degra- riencesrelativelylowannualrainfalllayer is installed above the insulation, the dation,themethodcalculatesaverageandshorterwetperiods,theaveragenegativeimpactonthermalresistance U-values for each PMRA system. Thesedecrease in R-value due to rainwater-re- issubstantiallymitigated.Underthis lated thermal losses is approximately 4.5configuration,R-valuereductionsare values are then used to estimate U rain,avg per cent. In contrast, in Vancouverasignificantlylowered,rangingbetweenthe average change in thermal trans- coastal city characterized by high rainfalljust3.1percentand6.4percent, mittance due to rainfallunder actual intensity and duration, particularly in thedepending on the climate. climate conditions. winter monthsthe reduction in R-valueThisanalysisprovidesmean-ingfulinsightsintotheperformance ofdifferentPMRAdesignsindiverse climates,supportingbetter-informed materialselectionanddesigndeci-sionsforyear-roundenergyefficiency. Importantly,theprocedurewasalso developedwiththegoalofseamless integrationintotheEnergy-RCIweb toolforfuturecodificationprocesses, enablinguserstoeasilyevaluatethe climaticimpactsonroofassemblies within a digital framework.STAYCONNECTED!REACH INDUSTRY STAKEHOLDERSWITH TARGETED PUBLISHINGAND ADVERTISING SOLUTIONS.Robert Thompson, Senior Vice President robertt@mediaedge.ca 647-494-422928 lROOFINGBClFALL 2025'