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Green Roofs: Engineer’s Perspective
NG Live!: Diane Cook & Len Jenshel: Gardens by Night
.
Up on the RoofA lofty idea is blossoming in cities around the world, where acres of potential green space lie overhead.
Green Roofs: Engineer’s Perspective
Early Example
Green Roofs: Engineer’s Perspective
Recent Example
Green Roofs: Engineer’s Perspective
Fit For PurposeDurablePracticalSafe
Green Roofs: Engineer’s Perspective
Fit For PurposeWhy Green ?
Green Roofs: Engineer’s Perspective
Fit For PurposeWhy Green ?How Green ?
Green Roofs: Engineer’s Perspective
Fit For PurposeWhy Green ?How Green ?Who Knows ?
Green Roofs: Engineer’s Perspective
DurableStrengthStability
Green Roofs: Engineer’s Perspective
DurableStrengthStabilityBuilding Envelope
Green Roofs: Engineer’s Perspective
DurableStrengthStabilityBuilding EnvelopePerformance
Green Roofs: Engineer’s Perspective
DurableStrength & Stability
Building EnvelopePerformanceReparable
Green Roofs: Engineer’s Perspective
PracticalAccessible
Green Roofs: Engineer’s Perspective
PracticalAccessibleUsable
Green Roofs: Engineer’s Perspective
PracticalAccessibleUsableFeasible
Green Roofs: Engineer’s Perspective
PracticalAccessibleUsableFeasibleOptimal
Green Roofs: Engineer’s Perspective
SafeFall Prevention
Green Roofs: Engineer’s Perspective
SafeFall PreventionSecure
Green Roofs: Engineer’s Perspective
SafeFall PreventionSecureWind-proof
Green Roofs: Engineer’s Perspective
SafeFall PreventionSecureWind-proofFire-proof
Green Roofs: Engineer’s Perspective
Fit For PurposeDurablePracticalSafe
Engage. Innovate. Inspire.
Slowing Down On Green Roofs
Peak Flow Attenuation and Volume Reduction
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Peak Flow Attenuation
Source: www.ec.gc. ca
Or With Green Roof
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Volume Reduction
Source: environmentalsciencesociety. org
Engage. Innovate. Inspire.
Slowing Down OnBlue Roof
Source: www.perviouspavement. org
Source: Alumasc
Roof D
ischargeD
ownstream
Storm
Sew
er or
Com
bined Sew
er
Engage. Innovate. Inspire.
Slowing Down OnBlue Roof
Source: www.perviouspavement. org
DETENTION AND EVAPORATION OFFERED BY BLUE ROOFS
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Slowing Down On Green Roofs Green Roof: Types
Intensive : > 8”, $$$$$
Extensive: 2” – 8”, $$, 17 – 50 lbs/sfBuilt-up or Tray Systems
Source: www.wbdg. org
Source: www.salinitymanagement. org
INTENSIVE SEMI-INTENSIVE EXTENSIVE
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Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, . . . Water designed to flow through medium vertically before laterally along drainage layer.
Source: www.greenroofplan. com Source: environmentalsciencesociety. org
VEGETATION
GROWING MEDIUM
FILTER / ROOT BARRIER
DRAINAGE
INSULATION
WATER-PROOFING
STRUCTURE
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, . . . Water designed to flow through medium vertically before laterally along drainage layer.
Special design considerations needed when designing a pitched green roof to preserve hydrological benefits of green roof.
Source: environmentalsciencesociety. orgSource: www.hydrotechusa. com
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration. . .
Source: www.princeton. edu
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, retention
Source: Paul MJ & Meyer JL, and USEPA
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, retention
Source:environmentalsciencesociety. org
Engage. Innovate. Inspire.
Slowing Down On Green Roofs
Source:Hydrological performance of extensive green roofs in New York City: observations and multi-year modeling ofthree full-scale systems. T B Carson et al 2013 Environ. Res. Lett. 8 024036 doi:10.1088/1748-9326/8/2/024036
Engage. Innovate. Inspire.
Slowing Down On Green Roofs
Source: enr.construction. com
Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, retention
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: detention, evaporation, infiltration, percolation, evapotranspiration, retention
Source: enr.construction. com
Engage. Innovate. Inspire.
Slowing Down On Green Roofs
Source: prairieecosystems.pbworks. com
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roofs: with cisterns or harvesting
Source: www.ce.t.kyoto-u.ac. jp
Engage. Innovate. Inspire.
Slowing Down On Green Roofs
Source: nusdeltares. org
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Green Roof: Effects of Rain Duration & Intensities
Source: uregina. ca (modified)
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Slowing Down On Green Roofs Green Roof: Runoff Quality & Pollution Control
Source: www.lid-stormwater. net
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Hydrological Selection of Green Roof Components:
Drainage
• Low Transmissivity Drainage Fiber Mat
• Drainage Layer
• Use of Lightweight Aggregate?
• Plastic Drainage Sheets ?
• Closed-cell polystyrene trays ?
• Maintain Aerated Conditions in the Growing Medium
• Ability to Remove Excess Stormwater without Causing Erosion
• Slope to Drain
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Hydrological Selection of Green Roof Components:
Growing Medium
• Sponge-like Water Holding Capacity• Inorganic Content & Material• Organic Content & Material• Saturated Weight of Growing Medium• Medium Thickness
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Hydrological Selection of Green Roof Components:
Selecting Plants
• Drought, wind and ice tolerant
• Prairie species
• Avoid large drifts of single species
• Water absorption
• Requires very little or no irrigation
• Requires very little or no fertilizer
Engage. Innovate. Inspire.
Slowing Down On Green Roofs Impact of Green Roofs on Urban Catchment
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Slowing Down On Green Roofs
Williams Engineering Canada Inc.
Inquiries:Williams Engineering CanadaBUILDEX Calgary, November 6, 2013
Wilma Leung C.Eng., MICE,LEED-AP Email: [email protected]
THANK YOU