ELT Easy Green™

 

Air Quality Improvement

• Gaseous pollutants are absorbed through photosynthesis and airborne particulate matter is trapped in the leaves.
• Gas exchange by the plants helps to add oxygen to the air therefore helping to reduce smog.
• Rooftop microclimate is produced with cooler due to transpiration of the plants therefore reducing the cost of the air transfer hot to cool in air conditioning = less expensive air conditioning. Less air conditioning means less electricity consumption which means less power generation from nuclear and fossil fuel burning plants which improves air quality further
• Green roofs cool the ambient air temperature (reduce the Urban Heat Island Effect) in cities which means less smog days.
• Studies have shown that 150 sq m of plant surface area produces enough oxygen for one person for 24 hours.
• Cleaner air is a direct benefit to asthma sufferers the elderly and young who are limited to indoor activities on " Bad Air" days

Toronto Atmospheric Fund

 

Temperature Regulation

• Green roofs help address the Urban Heat Island Effect which is the phenomenon of thermal gradient differences between developed and undeveloped areas.
• Most of the sun's energy is re-radiated as heat. Planted areas only reflect 20% of the sun's energy.
• Over 77 German municipalities invest in green roofs, as the population and urban areas developed the government started to tax storm water release from property owners, this has been the largest driver in creating the developed green roof industry in Europe.
• More than 1 in 10 flat roofs in Germany are green. Norway, Sweden, Japan, Switzerland and the United Kingdom are also greening their cities by using green roof technologies.
• Green roofs insulate buildings by external shading, cool industrial buildings and create microclimates, which can alter the climate of a city as a whole.

 

Reduction of storm water run off

• Perhaps one of the most important benefits of a green roof is the ability for the roof to aid in Storm water retention, by slowing the flow off the roof during a storm event. Moderation of water temperatures and natural water filters.
• Currently we have between 80-100 % drainage in most cities
• In a Natural Cycle 30% of the water is used by plants, 30% percolates to aquifers, 40% returned to the atmosphere therefore No surface runoff
• In a Metropolitan/Urban Cycle 5% to goes to aquifers, 15% to the atmosphere and 75% to surface runoff
• Major 2" rainstorm generates about 1.25 gallons per square foot of rainwater.
• A basic 2.5" extensive green roof retains about 0.5 gallon per square foot, or 40% of the rainwater that falls.
• On average in a 2" rain event 1" Sedum layer on 2" gravel retains 58% of water.
• On the same event 2.5" Sedum and grass mix retains 67% and 4" grass and herbaceous vegetation retains 71%.

The City of Portland, Oregon is a leader in developing and implementing green roof policies focusing on controlling stormwater runoff.

www.sustainableportland.org

 

Improvement of building performance

• German studies show that plant material growing on a roof can help a building retain up to 50% of the heat typically lost to convection.
• Waterproofing layer is protected from UV therefore extending life expectancy of membrane.
• Green roofs have the capacity to provide Sound insulation.
• Additional amenity space.
• Additional thermal insulation.
• Increased life expectancy of roof.

The National Research Council is currently studying the building envelope performance as well as the water retention capacity of various depths of media and plant cover.

 

NRCC Construction Research

 

NRC Study by Dr. Karen Liu - Energy efficiency and environmental benefits of rooftop gardens

 

Dr. Brad Bass and Bas Baskaran - Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas

 

LEED Certification Information

 

Habitat and Ecological benefits

• Possibilities for habitat preservation and protection of flora and fauna.
• Replaces land taken by buildings and thereby contributes to preserving biological diversity.
• Beautifies otherwise barren eyesores of our cityscape and provide unique opportunities for design and creativity.
• Increased urban habitat for song birds and butterflies.
• Health and horticultural therapy applications.
• Movement, colour, sound and texture of plants add to the overall health and well being of citizens.
• The community overall will also benefit from the environmental improvements mentioned above.

Common Misconceptions

• Water damage: Green roofs are designed to capture storm water runoff, by slowing the storm surge down; although the roofs act as a reservoir for a short period of time, the roof still drains. It is vital the roof drains properly. The performance of the roof will not be affected providing that the underlying roof itself is sound, drainage paths are kept clear and the membrane is good quality and is not damaged during installation.
• Root penetration: The plants and roots are separated from the membrane by the drainage layer and usually a root barrier is installed above the membrane for extra security (some membranes like TPO, PVC, EPDM act as root barriers already).
• If using vegetation such sedum on a shallow soil depth the likelihood of sedum roots penetrating below the growing medium is extremely unlikely.
• Green roofs are expensive and thus unaffordable. In fact, they're not. An ELT Easy Green™ system can cost as little as $7-12/sq ft installed.

Potential Issues

• Improper maintenance: If tree and woody plant seedlings are allowed to establish themselves on a roof meant only for extensive vegetation, there is potential for damage of the roof structure. This is why root barriers or protection measures are taken into consideration in the design of the green roof. This can be addressed in the specifications and warranty portions of tenders.
  - ELT solved this by electing to pregrow some of our green roofs which virtually eliminates most of the initial maintenance and significantly reduces most of the hidden costs associated with the maintenance.
• Specialized products and manufacturer compatibility can be difficult. Specialized knowledge of load, soils and plant material can create some design issues and this can understandably create a lack of client confidence in the concept. Check with your system provider to ensure you have complete details of the system chosen.
  - At ELT we are one of the only companies that deal with all of these potential issues in-house and our new ELT Easy Green™ system simplifies the design and installation greatly by combining almost all of the components into one component.
• Warranty Issues: who carries the warranties is not standard in the industry at the moment, sometimes it is the manufacturer, sometimes the roofer or general contractor and sometimes the green roof installer who carries the warranty.
  - ELT offers a comprehensive warranty for the vegetation and all green roof components including waterproofing see our product information for more details.