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TM59 Design Methodology for the Assessment of Overheating Risk in Homes Dr Anastasia Mylona, CIBSE Research Manager
London Climate Change Partnership - Heat Risk in London Group
September 19, 2017
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Overheating in homes• Overheatingidentifiedasanissue• Multiplestudiescallingforaconsistent
methodology
ArticlebyLizaYoungCIBSEJournalAugust2014
ZeroCarbonHubreportpublished
2015
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Whyisoverheatingaproblemnow?
• ClimateChange• UrbanHeatIslandEffect• Smallerhomes• Largerwindowsformaximumdaylight• Airtightnessforwinterenergyefficiency
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Designaspectsthatcontributetooverheatingrisk
• Singleaspectflats• Largeareasofglazing• Limitedventilation
• Restrictedopenings• Urbanhomes- noiseand/orair
pollutionlimitingnaturalventilation
• Communityheating
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• Noonedefinitionfitsall• Comfortissubjective• Dependsonbothenvironmental
andhumanfactors• Duration/timingofhigh
temperaturesisimportant• Veryhightemperatures>35°C
leadtoHeatstress• Highbedroomstemperatures
(>26°C)canimpairsleep Image from ZCH Overheating in homes - Where to Start - An introduction for planners, designers and property owners, 2013
Whatisoverheating?
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CIBSETM59
• Providesaconsistentdesignmethodologyfortheassessmentofoverheatingriskinhomes
• Basedontheuseofdynamicthermalmodelling
• Basedoncurrentknowledgeandresourcesbutsimplified
• Keyaimistohighlightdesignsthatareofhighriskofoverheating
Available for free:http://cibse.org/knowledge/knowledge-items/detail?id=a0q0O00000CQ83EQAT
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Definitionofoverheating- BasedonGuideAandTM52
Criterion1:Forlivingrooms,kitchensandbedrooms:thenumberofhoursduringwhichΔTisgreaterthanorequaltoonedegree(K)duringtheperiodMaytoSeptemberinclusiveshallnotbemorethan3%ofoccupiedhours.(CIBSETM52Hoursofexceedance)
Criterion2:Forbedroomsonly:theoperativetemperaturefrom10pmto7amshallnotexceed26°Cformorethan1%ofannualhours(33hours)
Bedroomsmustpassbothrequirements
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Standardisedinternalgainsandoccupancyprofiles
• 24/7occupancyofbedrooms(worstcase)• Daytime(10am-10pm)occupancyoflivingroomsandkitchens
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Weatherfiletobeused
Minimumrequirement• DSY1• Nearestlocation• 2020s• Highemissions,• 50th %ile
RecommendationtoalsotestdesignsunderDSY2/3or2050s/2080sdataforriskassessmentpurposesbutnotrequiredinordertopass
RecommendationtorunforDSY2/3or2050/2080sdatabutnotrequiredtopass
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Blindstobeincludedonlyifpartofthedesign• Ifblindsformpartofthemitigationstrategythenthesemustbeincludedin
thebasebuild• Resultswithoutblindsmustbeincludedinthereport• Blindsshouldnotinterferewiththeventilationcapacityofopenwindows,or
iftheydo,thisreductionintheircapacityfornaturalventilationshouldbetakenintoaccountinthedesign
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Otherkeyconsiderations
Openingofwindowsfornaturalventilation• Takingintoaccountanysecurity,noiseorairqualityissue• Windowsconsideredopenonlywhenroomsareoccupied,unlesssecure
openingsareprovidedVulnerableresidents
• CarehomesandaccommodationforvulnerableoccupantsshouldassumeTypeIoccupancy(seeCIBSETM52fordescription)
Communityheating• Heatlossesfrompipeworkshouldbeincluded
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