green roofs: beauty & functionality for the environment · best practices: green roofs: beauty...
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BESTPRACTICES
It is the mission of Stream Team to protect and enhance water resources and associated habitats and wildlife in Thurston County through citizen action and education. Stream Team is funded and jointly managed by the stormwater utilities of the Cities of Lacey, Olympia and Tumwater and Thurston County. www.streamteam.info
Ifyouarelookingforawaytoretrofitorbuildyourhomeaccordingtothelatestenvironmentallyfriendlymethods,tryusingliveplants!InGermany,itisestimatedthatgreenroofsalreadycomprise12%offlatroofs.InCopenhagen,Denmarkitismandatorythatallflatroofsundera30°pitchbevegetated.Now,intheeco-friendlyatmosphereofthePacificNorthwest,thistrendhascaughton.Withthenewlowimpactdevelopmentregulationstohelpcontrolstormwateronthehorizonandwiththeencouragementofpublicutilities,greenroofsareincreasinginpopularityandfrequencythroughoutthePacificNorthwest.Alsoknownaseco-roofs,vegetatedroofsandliving
roofs,greenroofscaptureboththeliteralandbuzz-wordmeaningsofthewordgreen.Vegetationisinstalledoverseveralunderlaymentsasthetoppartoftheroofsurfacetocreateanaestheticallypleasinglivingmedium.Greenroofscanbeinstalledonroofpitchesrangingfrom5°to40°.Vegetatedroofstreatpollutioninstormwaterandalsostoreasignificantamountofwater,furtherpreventingpollutedstormwaterrunofffromenteringourwaterwaysandcombinedsewersystems.Someofthemanyecologicalbenefitsofgreenroofsinclude:Energyusereduction
Duringan80°Fsummerday,ablackroofcanreach180°Fasopposedtoaplant-coveredroofwhichonlyreaches85°.Duringthewinter,agreenroofwillretain15-30%moreheatthanaconventionalroof.Thisinsulationtranslatesintolowercoolingandheatingcosts!(Lui&Baskaran2003,NationalResearchCouncilofCanada)Urbanheatislandreduction
Themoregreenroofsinanurbanarea,thelowertheambienttemperatureofthecity.Greenhouseeffectmitigation
Greenroofsradiatelessenergythanblackroofsintotheatmosphere.AUniversityofCaliforniaatBerkeleylabstudyfoundthatswitchingto“cool”or“white”roofsalonewouldbetheequivalentofremoving300carsfromtheroadsfor20years.Airqualityimprovementandcarbonsequestration
Photosynthesisremovescarbonfromtheatmosphereandstoresitasbiomass.
GreenRoofs:Beauty&FunctionalityfortheEnvironment
BESTPRACTICES:GreenRoofs:Beauty&FunctionalityfortheEnvironment 2of2
It is the mission of Stream Team to protect and enhance water resources and associated habitats and wildlife in Thurston County through citizen action and education. Stream Team is funded and jointly managed by the stormwater utilities of the Cities of Lacey, Olympia and Tumwater and Thurston County. www.streamteam.info
Addedhabitat
Nativevegetationattractsbutterflies,birdsandbees.Soundproofing
Outsidenoisecanbereducedfrombetween40-50decibelsdependingonthetypeofgreenroof.(Pecketal.1999)Lesswaste
Accordingtoresearch,agreenroofwilllengthenrooflifebyupto20years.(Miller,C.1998)Stormwatertreatment
Greenroofsreducetheamountofstormwaterrunoffandalsodelaythetimeatwhichrunoffoccurs,resultingindecreasedstressonstormwaterandcombinedsewersystemsatpeakflowperiods.Greenroofscanbedesignedandengineeredintwoways.Theinitialinvestmentpaysoffintermsofreducedenergycostsandtheincreasedlongevityoftheroof:Intensive
Theseroofsrequireaflatsurfaceandarewellsuitedtopublicorprivatebusinessesthatwanttoencourageroof-topgardeningand/orapark-likesetting.Adeepsubstrateof8-24inchesofsoilisabletoaccommodatelawns,ediblecrops,smalltreesandshrubs.Thishighload(35-120lbs.persquarefoot)requiresadditionalstructuralsupporttoincreaseload-bearingcapacity.Becauseoftheirincreasedweightandthepossibleneedtoaddanirrigationsystem,theseroofshaveahighercapitalcost.Theyalsohavehighermaintenancerequirements.Costofinstallinganintensivegreenroofbeginsat$25asquarefoot.Extensive
Theseroofsgenerallyweigh10-50lbs.persquarefootandarewithintheloadbearingcapacityofatypicalroof.Theyaresuitableforhomeorbusinessownerswhowantaself-sustainingroofthatrequireslowtono-maintenance.Theplantingsubstrateisshallow,containingfourtosixinchesofengineeredsoilmixandbestaccommodateslow-growing,fireresistant,drought-toleratevegetationsuchaslocalwildflowermixes,sedums,herbs,mossesandgrasses,typicallyona5-20°pitch.Extensiveroofsareonlyaccessibleformaintenanceactivities.Itcostsapproximately$10-24persquarefoottoinstallanextensivegreenroofwithrootrepellant/waterproofmembranesandotherkeyunderlayments.Componentsofagreenroofwillvarydepending
onthetypeandsizeofinstallationaswellasthemanufacturer.Awaterproofingmembraneiscriticalifthesystemisgoingtosucceedinthelong-term.However,severallayersofotherprotectivematerialsareoftenincludedtoachievewaterproofingandtoconveywaterawayfromtheroofdeck.Thefollowingdiagramillustratesthepossiblecomponents:
Growing Medium
Drainage, Aeration, WaterStorage Core
Insulation
Roofing Membrane
Structural Support
Vegetation
Root Barrier Filter Fabric
Separation Fabric
BESTPRACTICES:GreenRoofs:Beauty&FunctionalityfortheEnvironment 3of3
It is the mission of Stream Team to protect and enhance water resources and associated habitats and wildlife in Thurston County through citizen action and education. Stream Team is funded and jointly managed by the stormwater utilities of the Cities of Lacey, Olympia and Tumwater and Thurston County. www.streamteam.info
SPOTLIGHTONLOCALPROJECTS:Interestedinseeingsomegreenroofsinperson?Hereisapartiallistofgreenroofsthatyoucanvisit:
OLYMPIA:
TheEvergreenStateCollege:SeminarIIBldg,2700EvergreenPkwyNW,98505Type:Extensive|Year:2004WoodlandTrailRestroom,1600EastsideStreetSE,98501Type:Extensive|Year:2007OlympiaCityHall,6014thAveE,98501Type:Extensive|Year:2011
TACOMA:
Troy’sGreenRoof(Drivebyonly),3108South9thSt.,98405Type:Extensive|Year:2004
SEATTLE:
SeattleJusticeCenter,6005thAve.,98104Type:Extensive|Year:2002RussellInvestmentsCenter,1301SecondAvenue,18thFloor,98101Type:Intensive|Year:2006
PORTLAND:
HawthorneHostel,3031SEHawthorneBlvd.,97214Type:Extensive|Year:2002MultnomahCountyMultnomahBldg,501SEHawthorneBlvd.,97214Type:Extensive|Year:2003OregonHealth&ScienceUniversity(OHSU)CenterforHealth&Healing,3303SWBondAve.,97239Type:Extensive&Intensive|Year:2006
Resourcesforfurtherreadingandinformationonthegreenroofindustry:http://tinyurl.com/7q8k9ff(GreatphotosofEuropeangreenroofs)http://tinyurl.com/kpegg3s(Acontractor’sYouTubepage)http://tinyurl.com/ojn79eq(ArticleonthelargestgreenroofinPortlandforstormwatertreatment)www.greenroofs.org(Promotesthegreenroofindustrythrougheducationandadvocacy)www.lid-stormwater.net/(Informationonlowimpactdevelopment)www.greenroofs.com/(Atreasuretroveofinformationontheindustry)www.ecobuilding.org/(Localresourcesforlowimpactdevelopment)www.solterra.com(Seattlecompany; Sustainable Urban Developments)http://tinyurl.com/m8t8qk9(FactsfromtheEPA)
Source:StreamTeamNews,Winter2014