Green Roofs: Beauty & Functionality for the Environment · BEST PRACTICES: Green Roofs: Beauty...

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

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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