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Green Roofs Overview
 

Green Roofs Overview

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Kees Govers presents Green Roofs

Kees Govers presents Green Roofs

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    Green Roofs Overview Green Roofs Overview Presentation Transcript

    • Green Roof Systems What you need to know to implement effective green roofs Kees GoversLiveRoof Ontario Inc Mt Brydges, ON
    •  Green Roof Basics Extensive green roof systems Evaluating green roof systems Design tips An installation in 4 slides Innovative new greening techniques Questions
    •  Main reasons for installing green roofs  Stormwater management  Air pollution reduction  Urban heat island reduction  Energy use reduction  Replacement or increase of green space  Roof life extension  Aesthetics  Green roof mandates  Contribution to LEED credits
    • What makes a green roof work? Plants utilise solar radiation  Photosynthesis creates carbohydrates and O2 from H2O and CO2  Respiration produces plant growth and CO2  Respiration and photosynthesis create transpiration  Transpiration draws H2O and O2 from substrate along with nutrients  Growing medium absorbs and holds H2O and O2 until transpired  Filtration and buffering takes place in the process
    • LEED Sustainable Sites Credits 6.1 & 6.2 Stormwater Design: Quantity control & Quality control  Storm Water Retention  Storm Water Detention  Storm Water Filtration
    • Storm Water Retention Defined by the absorptive capacity of Green roof system  Growing media 20-45% by volume  Plants depends on plant type and turgidity  Water retention fabrics  Water retention cups Green roof system auxiliaries  Cisterns
    • Where does the retained water go? Evapotranspiration  Succulents (facultative CAM)  Grasses (mostly C-4)  Perennials (mostly C-3) Photosynthesis Surface evaporation
    •  What happens during a drought?  Succulents  Switch to CAM  Reduce evapotranspiration  Cuticles get thicker  Plants physically shrink  Plants loose mass (mostly water)  Death occurs after very long drought  Recovery time from drought: less than 24 hours
    • Allium schoenoprasum ‘Forescate’Sedum ellacombianum
    •  What happens during a drought  Grasses (C-4)  Reduce evapotranspiration  Cuticles get thicker  Plants abort flowers and seeds  Plants shrivel up  Plant crown goes dormant  Death occurs after variable fairly long drought  Recovery time from drought: up to several weeks
    • Koeleria macrantha Schyzachyrium scoparium
    •  What happens during a drought  Perennials (C-3)  Reduce evapotranspiration  Cuticles get thicker  Plants abort flowers and seeds  Plants shrivel up  Plant crown goes dormant  Death occurs after variable length drought  Recovery time from drought: weeks to months
    • Penstemon digitalis Aquilegia canadensis
    •  Stormwater detention and filtration  Effectiveness depends on  Stormwater retention  Rainfall intensity  Saturated conductivity of growing medium  Plant density  Denser plantings prevent surface runoff
    •  Storm water quality improvement  Buffers water pH  Filters pollutants  Organic compounds  Heavy metals  Particulate matter
    • Reduction by deposition on foliage Particularly effective for  Particulates  NO, NO22011 Lancaster University Study Particulates up to 60% reduction NO, NO2 up to 40% reduction
    • Sustainable Sites credit 7.2 Heat island Effect: RoofLower roof temperatures  Reduced heat transfer into buildings  Lower HVAC loads  Reduced roofing membrane stress  Improved photo voltaic cell performance  Lower temperatures above the roof
    • How does a green roof compare to a white roof?  Lower surface temperature in the summer sun  Higher temperature in the winter  Effectiveness does not depend on cleanliness  Does not cause glare  Does not bounce solar radiation to other surfaces  Does not deteriorate under UV light
    • Intensive ExtensiveGrowing medium depth 300mm and deeper 65mm to 150mmSaturated load 400 kg/m2 and over 50 – 250 kg/m2Plants Trees and shrubs Succulents, grasses, perennialsMaintenance High lowIrrigation Always Depends on design
    •  Four critical factors  Drainage  Growing medium  Plants  Plant coverageNothing else matters  A stressed green roof doesn’t function properly!  A dead green roof doesn’t function !!!!
    •  Built in place systems Pre-grown blankets Modules Hybrid Modules Stoney Creek Library London
    • • Built up system• Hand planted• Slow growing due to heat and cold• Vulnerable to weeds• High maintenance 27
    • Ottawa, ON, 1 season oldGrand Rapids, MI 1 yr old
    • • Takes a long time to grow in• Mini monocultures of deciduous plants leave soil exposed• Lacks succession in design 29
    • CMC GatineauMEC 1998 Mature built in place green roofs
    • Blanket installation Blanket system assembly
    • Blankets as part of a built in place system
    • What industry wide protocols exist? 5 ASTM Standards (All based on German FLL Standard)  ASTM E2396-05 standard test method for saturated permeability of granular drainage media  ASTME2397-05 Standard practice for determination of dead loads and live loads associated with green roof systems  ASTM E2398-05 Standard Test method for water capture and media retention of geocomposite drain layers for green roof systems  ASTM E2399-05 Standard Test method for maximum media Density for dead load analysis of green roof systems  ASTM E2400-06 Standard guide for selection, installation and maintenance of green roof systems
    •  Toronto Green Roof Standard  Only comprehensive enforceable green roof standard in North America FM Global approvals standard 4477 for vegetative roof systems FLL Guideline for the planning, execution and upkeep of green roof sites, release 2008
    •  Drainage Growing Media Plant Selections Edge effect Irrigation Wind uplift performance Maintenance requirements
    • Typical drainage layersFor built in place
    • Typical drain layer used under mats
    • Engineered growing medium •Designed to remain on the roof, very durable •No stabilizing agents should be needed •No short term lightweight fillers •No perlite or vermiculite •No horticultural foam or Styrofoam beads •No more than 5-6% organic matter (by pyrolysis test) •No hydrogels (not legal in Canada for growing media)• Falls within FLL Standard parameters
    • Poor Growing medium choice •Too coarse •Too little organic matter •Tough for plants to establish
    • April 2010Poor Growing medium choice •Too much organic matter •Poor aeration when saturatedPlants grow too fast initiallyPlants start dying after about 4-5 years May 2010
    • Very shallow growing medium
    •  Growing media specifications  Be as specific as you can  Demand an FLL test report  At time of submission  Just prior to installation  For modules at time of filling  Ask for physical samples  Only accept substitutions is they meet the above criteria
    • Get to know your supplier and their suppliers Plant producer  Quality of plants  Propagation facilities  Production capacity  Handling equipment Delivery equipment (for module suppliers) Installation equipment  Blower trucks  Conveyor belts  Delivery racks
    • Stock beds
    • Production Capacity and equipment
    • Depends on:  Depth of growing medium  Design of the green roof  Intended purpose of the green roof  Irrigation or not
    • Succulents Grasses PerennialsMedia <75mm With irrigation no NoMedia 75 to 150mm yes With irrigation With irrigationMedia >150mm yes some some Combination plantings are preferred • Better winter survival • Better drought survival • Healthier plants
    • Plant installation limitations Succulents Grasses PerennialsSeed Takes a long yes some timeCuttings Small window no NoPlugs Spring and fall Spring and fall Spring and fallmats Spring and fall Spring and fall noPregrown modules Above 2 C Above 2 C Above 2 C
    • 150mm depth, no irrigation• Aster• Solidago• Juniperus horizontalis• Scabiosa• Geranium• Sedums• Alliums• Sempervivums• Calamintha• Nepeta• Agastache
    • 2006 Timber Press Snodgrass&Snodgrass Best North American book on extensive green roofsRegional LiveRoof Plant Selections Guide
    • Eglinton West Station
    • Victoria Park Station
    • Stoney Creek YMCA & Library, London
    • Toronto City Hall podium
    • • Exposed Edges• No soil connectivity• Plants dry out along edges• Plant roots are affected by cold• Slower growth as a result 68
    • • Exposed plastic and gaps between modules negatively affect plant performance 69
    •  Michigan State research (to be presented at CitiesAlive) Based on 30 minute irrigation events  Overhead irrigation  25% more water applied than drip or sub  20-30% run-off of total applied  Even distribution  Drip irrigation  25% less water applied  80% plus run-off of total applied  Poor distribution  Sub irrigation  Worse in all respects than sprinkler or drip
    • Drip lines with 6” spacing (normal is 12”)After 10 minutes After 60 minutes Waste water
    • Appropriate use of drip irrigation
    • Drip irrigation failure
    •  Relative costs and embedded energy  Line spacing  Sub: under entire green roof system  Drip: 300mm spacing between lines  Sprinkler: Up to 12 metre spacing between lines  Installed cost in TO  Sub: $40 -$60/m2  Drip: $20-$35/m2  Sprinkler: $15-$20/m2  Maintenance  Sub: near impossible  Drip: clogged lines need to be replaced  Sprinkler: easy maintenance and malfunction detection
    •  City of Toronto requires  Wind uplift study of each building according to OBC signed by a professional engineer  Wind uplift pressures in kPa (or psf) 2015 version of National Building code will require wind uplift rating for:  Roofing systems  HVAC units  PV installations  Green roofs  Pavers
    • How wind uplift pressure is calculated:  Formulas in OBC  Mathematical exercise  Scale wind tunnel testing  Usually done for building models of unusual shape  Full size dynamic testing  Testing on full scale products  Test protocol developed by NRC Canada  CSA A123.21-10
    •  CSA A123.21-10  Dynamic wind uplift test protocol  Test rating may be required for all green roof systems.  Untested systems will be rated at dry weight of system  Only one system tested to date.
    • Regent Park Block 24
    • Mature plants resist scour
    • Low maintenance planting
    • Medium maintenance planting
    • High maintenance planting
    • High maintenance
    •  Nutrition Preliminary findings at U of G  Maintenance concentration of macro nutrient important  Source of nutrients is unimportant  Healthiest plants at modest levels of nutrition  Starving plants does not toughen them  Overfeeding plants kills them
    • Install pavers, edging and irrigation before the plantings
    • Overhanging roofs require irrigation
    • Stone Pavers Installed against a South Facing WallPrevent scorching
    • Roof with Exposed Membrane Roof without Exposed Membrane
    • Distressed and Dead Plants Due to Excessive Foot Traffic
    • Severe traffic damage by other tradesAvoidable by proper sequencing
    • Plant Death Caused by Roof Vent Air stream
    • Roof Access Point with Stone Pavers
    • The Blank Canvas •membrane replaced •EFVM installed •Asphalt flood coat applied
    •  Installation Day 1
    • Installation End of Day 2
    • Installation End of Day 4
    •  Greening can happen anywhere on any scale Exercise due diligence in selection and execution Don’t be afraid of innovative ideas
    • Contact InformationKees GoversLiveRoof Ontario Inc23078 Adelaide RdMount Brydges, ONN0L 1R0 Canada(519) 245-4039kees@liveroofontario.cawww.LiveRoof.ca Toronto Police Academy