2012 Annual Conference-Holmes-Green Roofs
43
Omaha Metro Green Roofs Kent E. Holm, CSM Douglas County Environmental Services Director
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Transcript of 2012 Annual Conference-Holmes-Green Roofs
Omaha Metro Green Roofs
Kent E. Holm, CSM Douglas County Environmental Services Director
Outline for today …
• History of green roofs in the metro. • Development of industry standards. • Metro green roofs – comparing and
contrasting. • Maintenance issues.
History
• Green Roofs for Healthy Cities market development symposium – October 2007 – Challenges and obstacles to the implementation of
green roofs • Appraisal and Financing • Insurance • Technical specifications • Restrictive covenants • Building codes • Policies
– Green Roof Working Committee
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The symposium served to initially provide basic information about green roofs and then to identify specific challenges and obstacles to the implementation of green roofs in the metro-Omaha area. From that a “Green Roof Working Committee” was formed with Kent Holm as the Chair. Six (6) subcommittees then evaluated various aspects of the “challenges and obstacles” and developed recommendations and information. All subcommittee recommendations were included in a technical memorandum. That TM is available at the Douglas County Environmental Services website (www.dcplanning.org - click on the “Green Roof Committee.”
Changes in the industry
• Industry standards were needed to address specific issues. – Wind scour – Fire prevention – Root penetration
• ANSI (American National Standards Institute)
standards have been developed in these areas.
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Provide references to those standards in a list of technical resources.
ANSI/SPRI VF-1 External Fire Design Standard for Vegetative Roofs
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Saddlebrook. This was the first area planted and they started with a defined “row” pattern. Contrast this with the preceding photo with the “random” placement of the sedum varieties.
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This is one of the few places on the roof where the silver-green variety does well. This is an east exposure but protected by a wall on the north.
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Dunsany Flats green roof (sedums, blue glass, and rock) over a parking garage.
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Green Grid tray type system. Note the plastic that is still exposed. This type of system does not provide as much insulation benefit as the grown in place system, nor does it moderate the temperature extremes (i.e. it likely doesn’t provide as much protection for the roof membrane).
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Compare this photo of the Saddlebrook roof with the preceding one. Note the “red” sedum that is mostly non-existent in the Health Center roof. Both roofs had the same initial sedum varieties.
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Green Grid tray system. Note the triangular-shaped trays that were required to fit around the drain.
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Farm Credit Services, 118th and Q. Note the mesh material. This is to minimize wind scour. Over time it will break down but hopefully not before all of the plants have grown together. They opted for a 3 year maintenance contract on the green roofs.
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Farm Credit Services – north exposure. Note the difference between the right and left half of this area. Certainly appears to be related to sun exposure.
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Farm Credit Services – east exposure. Note the differences in plants.
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Note the irrigation valve box. Point out the value in using irrigation on green roofs because it increases the insulation value in addition to facilitating plant growth. Information in the past couple of years has suggested that based on the comparative cost of water it is better to irrigate a green roof rather than use the corresponding amount of water generating electricity to cool the living space below.
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Farm Credit Services building, 118th and Q. This is a ground level roof on the north side of the building so significant shade.
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Gallup green roof on their Missouri riverfront building.
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Interesting to see how the various plants are competing and coexisting.
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Gallup – more variety of plants; deeper soil media (8” depth and then deeper in the planters). This is the same Green Grid system that was used at the Health Center.
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The blue fescue is for the most part being shaded out by the taller plants.
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View to the south. Note that the condo building in the background also has a green roof on a portion of the building.
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There are two large planter boxes that have the Euonymus and small trees. The trees are not doing as well and still have staking on them. The ones further from the building seem to be doing better.
Microclimate impacts
