Benefits
I.
Stormwater Mitigation
II.
Urban Heat Island Effect
Mitigation
III. Cooling/Heating Load
Assistance
IV.
Extended Roof Lifespan
V.
Air/Water Purification
VI.
Sound Deadening
VII. Creation of Wildlife
Habitat
VIII. Psychological Benefits and
Aesthetic Improvements
IX.
Value of Building Increases
X.
Cost Effective!! – Ecoroofs
Cost More, Right??
Marketing Green Roofs - Exercise
Hawthorne Condominiums
I. Benefits
Stormwater Mitigation:
In Portland, as in most areas, stormwater is now recognized as the number
one cause of degraded urban stream health. This is an especially serious
issue for our Rainy City because our waterways once supported wild
populations of salmon.
The city is developing a
“stormwater discount” that
may give a significant
savings off the water bill.
Stormwater fees are
projected to increase
significantly in the near
future and may grow to
35% of our water bill. We
may save up to 100% of
this portion of the bill.
Photo Courtesy Tom Liptan
Degraded Runoff
The Rainwater Sponge
• Plants absorb rainwater for
photosynthetic processes
• Plants reintroduce water into the air
through evapotranspiration
• The soil acts like a sponge,
absorbing water, much of which is
released to the air through
evaporation.
• These processes typically absorb
30% to 50% of rainwater that falls
on ecoroofs in Portland
• The effect on the storm sewer
systems is a lower peak and a
flattened curve for stormwater flow
• This effects temperature, peak flow,
and quality of the remaining runoff
• There is Five to Seven times more
residential rooftop than
Commercial Rooftop area
– And this Provides a great
opportunity to reclaim our
watersheds!
A 1,500 sq. ft. roof will shed 34,000
gallons of rainwater a year.
I. Benefits
Urban Heat Island Effect:
Public Benefit to the Urban Climate
II. Urban
Heat
Island
Effect
III. Cooling/Heating Load Assistance:
•
•
•
•
Surface temp reduction of 14 – 22 deg.F during summer. ( 4” of soil)
Significant wind chill reduction, reducing heat demand by 5% to 25%
Greenroofs function as either an insulator or heat sink, depending on moisture level. Either
way, they help mitigate temperature extremes.
The Biggest Benefit Realized to the Property Owner is Realized in Summer Cooling Costs
– HVAC air conditioning units on greenroofs take in cooled air instead of superheated air. Energy
Savings is Significant during the Summer months.
– Evaporation of moisture in Soil and Plants Cools the Roof Significantly, Helping to Cool the
Entire Story Immediately Below It.
– Any Energy Savings during peak hours (like with air conditioning use) translates into a need for
less energy generating infrastructure. The real savings here is far greater than the savings you see
on your electricity bill.
Cold
Hot
Photo Courtesy Tom Liptan
Graphic courtesy of Zincoflor
IV. Less Likely to Leak than Asphalt or Shingles, And Lasts 2-3 Times As Long!
• It All Starts with a Higher Quality Membrane System, Designed to Last at
Least 20 Years on a regular roof system.
• It’s Topped with Soil and Plants, Both of which Protect it from its two
Enemies, Cumulative Sunlight Exposure, and Temperature Extremes
• Sunlight’s UV Rays Eventually Lead to Failure of the Elastomers
• Temperature Fluctuations or Extremes Lead to Overflexing the roofing
materials beyond their capacity.
• But Ecoroofs function as either heat sinks or insulation, thereby holding a
more constant temperature at the membrane level. At the same time, the
plants absorb the sun’s rays and also help shade the soil, which, of course,
shades and protects the membrane!
Hawthorne Hostel Ecoroof
Installed August 2002
V. Sound Reduction:
•
•
•
•
•
Absorbs both ambient and penetrating sound waves
Sound insulation improved by up to 8 dB
Reflected sound reduced by up to 3 dB
Vegetation absorbs high frequencies
Soil absorbs lower frequencies
Building in the
flight path of an
Airport
Photo courtesy of American Hydrotech
Graphic Courtesy Zincoflor
VI. Air/Water Purification:
• Vegetation Reduces Dust by Trapping Particles
• Nitrates and other harmful materials are filtered out of rainwater and air and
bound within the soil.
• Beneficial Effect on Water Turbidity, Chemistry, and Temperature of Runoff
• Absorbs Carbon Dioxide, Produces Oxygen
Residential Greenroof in
Germany
VII. Wildlife Benefits:
•Wildlife Habitat and Greenspace Created up to 100% of Building Footprint
•Inviting Nature back into the built environment
•Increasing our Urban Biodiversity
Beekeeper’s
Roof
Provides
Nectar for
His Native
Honeybees
VIII. Livability/Aesthetic Benefits
•Eliminates Glare
•Creates an “Amenity”
•Positive Social Effect, Showcasing Stewardship of the Earth.
•Positive Psychological Effect
•Possible to Grow Food on Ecoroofs.
•Harvest Fresh Herbs for Cooking
IX. Value of Property Increases
•Once Banks recognize greenroofs as “amenities” they will be willing
to loan out more money for projects involving greenroofs.
•Property Instantly Recognized as “Green” if roof is visible
•Ecoroofs can Create a Beautiful View, thereby Increasing Property
Values, or Rental Rates
X. Cost Effective, with the right knowledge!
•You are Learning about Lower-Cost, Locally-Available Materials and Designs
Successfully Installed in Our Area.
Graphic Courtesy of Steve Cowden, The
Oregonian
An Example of Low Cost Materials, Used in an Ecoroof
Costing $7.50/ ft2. (materials and retrofit)
Or… Same Cost as a Regular Roof!
•Because greenroofs Last 2-3 times as long, over the life of the roof, they save
the cost of at least one conventional reroofing.
•If it outlasts the conventional roof by three times, the greenroof can cost the
same as a regular roof.
•This is called “Life Cycle Cost Analysis”
•Most Homeowners and Developers use Up Front Cost Analysis, However.
Former Ecoroof Workshop Location
List All the Private, and Public Benefits for the Following Project:
• New Garage – ( 400 ft2
roof, 20 lbs/ft2)
• Mandated Stormwater
Mitigation Required for
Further Site Development
• Homeowners are an Avid
Cook, and a Landscape
Architect
• Roof is Visible from
Second Floor of House and
2 Neighbors’ Homes as
Well
• Homeowners Plan to Keep
the Property for at Least 20
Years
• (Project is Using Cost
Effective and Best
Practices, like We’re
Learning in Class)
Public Benefits
Private Benefits