b'SOLAR REFLECTIVITY THE IMPACT OF SOLAR REFLECTIVITY OF GLAZING ADJACENT ROOFSAn RCABC research projectIntroduction This phenomenon is not new. In 2010,experienced premature exhaustion of ThesamesolarultravioletlightthatLas Vegas hotel guests were burned byanti-aging components such as antiox-warms the earth and produces thoseconcentrated solar radiation from hotelidants, UV [ultraviolet] absorbers, and nostalgic summer breezes also causeswindows.Hotelstaffjokinglydubbedheatandlightstabilizingcompounds erythemasolare(sunburns)andtheMGMResortsphenomenonthewithin TPO. 2candestroyanewroofmembrane.death ray 1 . Those same death raysForthemostpart,theseissues Unlikeourskin,exposedmembranecausedvinylsidingtomeltonhomesseemed to plague only plastic construc-roofsaredesignedtowithstandtheacross the USA and Canada as sunlighttionmaterialsusedinhot,aridand normalabsorptionofultravioletreflected off windows (Figure 1). semi-aridsouthernregions.However, radiation, but when that light energyIn 2009 and 2010, reports from thein2019,theUniversityofBritish isfocused,particularlybyreflectiveASTM TPO task group and the MidwestColumbiacontactedRCABCabouta windows, metal flashing, or wall clad- Roofing Contractors Association (USA)UBC building that exhibited widespread ding,theelevatedtemperaturescanstated that TPO membranes subjectedblistering. Of the three roof areas on wreak havoc with adhesive bonds intoconcentratedreflectedsunlightthe relatively new building, the south-some roof membranes and warp andeast2-plySBS-modifiedmembrane blister them. 1 www.reuters.com (October 1,2020). roofshowedoddsignsofpremature aging and failureodd because the blisters and racking followed a partic-ularpatternthatwasnotreplicated ontheotherroofs,andbecausethe same issue was affecting relatively new blister repairs.After an extensive examination of all three roofs (including cut tests), and a thorough review of design and construc-tion documentation, we suspected solar reflection from adjacent windows may be contributing to the blisters.The AERL Roof ProblemTheAquaticEcosystemsResearch Laboratory (AERL) at the University of British Columbia (UBC) is a concrete structuresituatedinVancouverswest end on UBC lands, less than a kilometer from the Strait of Georgia (Figure 2). Constructed in a marine climate (Zone 4), the building is long and rectangular (approx. 220 x 70 feet), oriented on a near east-west axis. Three separate roof areas comprise the entire roof structure 2 Christopher McGroarty and Thomas J. Taylor, A study Figure 1: Note the peculiar swath of melted siding material, attributed to the path of the sun across the sky.of longevity (Professional Roofing: February 2014 Melted Vinyl Siding, Issue 228 (June/July 2012): finehomebuilding.com. digital issue).22lROOFINGBC l SUMMER 2021'