Ｇreen Sky by Yushan Cheng

CONTENTS INTRODUCTION

WHAT IS A GREEN ROOF?

WHY GREEN ROOF?

KINDS OF GREEN ROOF

GREEN ROOF IN USE

GREEN ROOF BENEFITS

LEARN MORE

THE GREEN SKY APP

THE GREEN ROOF KIT

It's the convergence of jobs, energy, climate and health that provides incentives for green infrastructure and the potential for significant returns on investment.

INTRODUCTION

The Hanging Gardens of Babylon is generally considered the first example of “green roof.”

WHAT IS A GREEN ROOF? GREEN ROOF REFERS TO A SYSTEM OF ROOFING THAT USES PLANT LIFE FOR ROOF COVERING INSTEAD OF TRADITIONAL COVERING MATERIALS. The idea of rooftop greening dates back thousands of years. Civilizations in Mesopotamia originated the concept, and Greeks, Romans, Persians, and other cultures had some form of roof gardens to green and cool their often brutally hot landscapes. The famed Hanging Gardens of Babylon, for example, were actually planted on rooftops. Today, a green roof doesn't refers to painting the roofs green, or having plants in pots, but to a change into the use of technology for an ecological function to improve the habitat or to save in energy consumption. It is a roof of a building that is partial or totally covered with vegetation, either directly on it or a cultivation medium, that serves an ecological function. Therefore, green roof takes a lot more than putting a bunch of plants together. Involves the use of technology to redesign and improve the area where it will be placed, specially on creating a suitable area for plants to grow on what used to be solid surface made of concrete.

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WHY WE NEED GREEN ROOFS URBANIZATION IS UNAVOIDABLE. YOU CANNOT STOP IT. SO, IT IS BETTER TO PREPARE FOR IT. Over the past hundred years, the global urban population has swelled from 15% to 50% of the total global population, which itself has increased from 1.5 to well over 6 billion. According to the US National Research Council, by 2040, the world’s urban population is expected to have grown from 3.5 billion to 5.6 billion. The future is going to look pretty urban with more and more people shifting to cities to the point that, after 28 years, we’re going to have two thirds of all the people in the world living in cities. Because of the earth’s population keeps increasing, there is a need for increased densities in urban residential development, which could result in terrestrial green space being reduced or lost. Resource limitations and environmental degradation are becoming more apparent every day.

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“If we steal the ground for a building, we can give it back to nature on the roof.” —Wolfgang Ansel

The necessity to recover green space is becoming increasingly critical for the health of our environment as well as our well–being. And green roof system is a wonderful solution for the environment today

for several key reasons. Because the rooftops in urban areas spend all day gathering heat from the sunlight, at night they create a Heat Island Effect, radiating out the heat they've absorbed. This has been shown to actually change the normal temperature of urban places. Green roofs, however, would mitigate this effect, and instead of absorbing the heat, absorb the carbon dioxide in the air. Green roofs can also help cleanse the air and absorb waters from rainstorms and prevent overflow in gutters and sewers. Green roofs also provide much needed habitat for animals that would otherwise be out of luck. Birds and pollinating insects benefit from the return of plants that disappeared when the buildings were built. Green spaces provide people with a wonderful respite from the hard, grey urban setting. When we spend time in nature, we're not only nicer and healthier, but we are more likely to want to protect the environment. That's an important side effect of green roofs.

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GREEN FOR BETTER CITIES

KINDS OF GREEN ROOFS THERE IS NO SINGLE KIND OF GREEN ROOF THAT WORKS FOR ALL BUILDINGS, CLIMATES AND CLIENT NEEDS. Green roofs can be categorized as “intensive” or “extensive,” depending on the depth of growing medium. But all green roofs involve a high quality water proofing and root repellant system, a drainage system, filter cloth, a growing medium and plants.

NATURE

GREEN ROOF SYSTEM

Growing Medium Topsoil

Filter Sheet Drainage Layer

Weathering

Protection Mat Waterproofing

Sourcerock

Roof

Intensive green roofs are often used on commercial buildings. They range in thickness from 6–15"+. These intensive systems are most applicable on flat, level roofs which are structurally engineered to hold their tremendous weight. This style is more permissible for human access and recreation, and therefore includes walkways, terraces, and other structural features to make it an enticing public space to spend time. However this style of planting will most likely require irrigation and maintenance as opposed to the extensive systems which are minimal care. As these rooftop gardens are much more elaborate, they also tend to be more expensive to install in comparison to the extensive system.

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Extensive roofs are more often used for single family and multi–family residential buildings. They are much shallower, typically only 2–4" deep, and are planted with particularly hardy plants. They are designed to be lightweight and to maximize the performance and environmental benefits. They are less expensive and very low maintenance. Extensive greenroofs can be constructed on slopes up to 30°, and steeper ones can be installed with raised grids or laths to hold plants and soil media in place.

INTENSIVE GREEN ROOF

EXTENSIVE GREEN ROOF

SOIL DEPTH

Thin growing medium

Thick growing medium

SOIL DVEPTH

> 6''

&drainage layer

& drainage layer

< 4''

Can only be built

Can be built on

on flat roof

pitched and flat roof

Always

No need for

irrigated

irrigation

High

Low

Maintenance

Costs High

Costs Low

($20–40/ft²)

($10–20/ft²)

Heavyweight

Lightweight

(102–410 lbs/ft²)

(13–37 lbs/ft²)

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An example of intensive green roof: the Toronto City Hall Podium Green Roof has been named one of “Toronto’s Green Gems” by the Toronto Star.

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An example of extensive green roof: a green roof grows in Denver. The viewing deck for this sedum â&#x20AC;&#x201C;filled roof is on the 9th floor of the Environmental Protection Agency.

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GREEN ROOF IN USE

One of the many benefits of installing a green roof is the appeal it will have on wildlife.

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GREEN ROOF BENEFITS GREEN ROOFS ARE NOT ONLY A VISUAL IMPROVEMENT OVER TRADITIONAL FLAT OR SHINGLED ROOFS. Even today, the opportunities of green roofs are still underestimated. The “natural look” is only one obvious credit within the broad range of arguments for green roofs. Further benefits of green roofs include the protection of waterproofing, water retention, thermal insulation, improvement of the climatic environment as well as new natural habitats for flora and fauna. No other architectural style provides such a wide range of positive effects for buildings, inhabitants, and the environment. Thus, green roofs meet one of the essential conditions of sustainable development, the reconciliation between economy and ecology. The figures at below are provided as generic examples.

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FINANCIAL BENEFITS MODERATION OF URBAN HEAT ISLAND EFFECT & REDUCED HEATING AND COOLING COSTS Through the daily dew and evaporation cycle, plants that on vertical and horizontal surfaces are able to cool cities during hot summer months, also reduce the Urban Heat Island effect—the phenomenon of metropolitan areas being significantly warmer than surrounding rural areas, due to the heat–reflecting nature of concrete and other man–made materials and the release of heat from air–conditioning systems and machinery. 92˚ 90˚

85˚

Rural

Urban Residential

Downtown

Park

The reintroduction of vegetation into cities promotes natural cooling by absorbing, instead of reflecting, the sun's rays, and through evapotranspiration. Traditional black roofs can reach temperatures of 158°F, and as a result have an enormous effect on building and ground level temperatures. When the outside temperature is 77 to 95°F, a gravel roof can reach 140 to 176°F. Green roofs remain at the same temperature as the outside air, and rooms under a green roof would generally be 37–39°F less than that. One study concluded that 25% green roof coverage can reduce the urban heat island effect by up to 1.8°F, and you could save up to 75% of cooling costs and 25% of heating costs with a green roof.

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RECEIVE TAX CREDITES In the terms of tax incentives, tax abatements, and outright grants there are many different kinds on the Federal, State and Municipal level —but they require some digging around. For example, in many municipalities near rivers, estuaries and waterways, there are significant Stormwater Abatement incentives. DSIREUSA aggregates all kinds of national tax credits revolving around sustainable building practices and renewable energies. The EPAct (Energy Policy Act) allows for a Federal tax credit of up to $1.80/sq.ft. for new or existing commercial buildings that are constructed or reconstructed to save at least 50% of the heating, cooling, ventilation, water heating, and interior lighting energy cost of a building that meets ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers) Standard 90.1–2001. A Green Roof can help you earn 60 cents toward that credit (and you can go for just that portion of the total credit). Many green roof design/build companies offer services to help their clients navigate the world of incentives—in short, they help their clients find those credits & dollars on a Federal, State and Municipal level.

TAX

New York State Law in larger cities: you can receive a one year tax credit of up to $100,000 (or $4.50 per sq/ft) for green roof installs that encompass at least 50% of available roof space.

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RECEIVE LEED CREDITS LEED, or Leadership in Energy & Environmental Design, is a green building tool that addresses the entire building lifecycle recognizing best–in–class building strategies. Comprehensive and flexible, LEED can help you in the following ways:

TAX

Lower operating

Conserve energy,

Be healthier and

Qualify for money

costs and increase

water and other

safer for occupants

saving incentives

asset value

resources

At its core, LEED is a program that provides third–party verification of green buildings. Building projects satisfy prerequisites and earn points to achieve different levels of certification. Building a green roof on either existing building or new construction, both can earn LEED credits. Depending on the other LEED strategies you are considering for the building to receive LEED certification, a Green Roof can add up to 14 points.

INCREASED ROOF LIFESPAN Green roofs can reduce temperature variations and block UV radiation mean that the waterproofing won not deteriorate over time as it would in a typical roof. Therefore, you could expect your roof membrane to last 2 to 3 times longer than usual 50 to 100+ years.

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MARKETING Green roofs can increase a buildingâ&#x20AC;&#x2122;s marketability, because they are an easily identifiable symbol of the green building movement and can act as an incentive to those interested in the multiple benefits offered by green roofs. Green roofs as part of the green building movement, have been identified as facilitating: sales, lease outs, increased property value due to increased efficiency, easier employee recruiting, and lower employee and tenant turnover.

FILTRATION OF POLLUTANTS OUT OF THE AIR Green roofs can also help reduce the distribution of dust and particulate matter throughout the city, as well as the production of smog. A green roof on a typical oneâ&#x20AC;&#x201C;car garage will remove 18 lbs of airborne particulates per year and generate enough oxygen to supply more than 25 people with their yearly requirements.

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PUBLIC BENEFITS STORMWATER MANAGEMENT With green roofs, water is stored by the substrate and then taken up by the plants from where it is returned to the atmosphere through transpiration and evaporation. In summer, depending on the plants and depth of growing medium, green roofs retain 70–90% of the precipitation that falls on them; in winter they retain between 25–40%. For example, a grass roof with a 1.5–8 inches layer of growing medium can hold 4–6 inches of water. Green roofs not only retain rainwater, but also moderate the temperature of the water and act as natural filters for any of the water that happens to run off. Green roofs reduce the amount of stormwater runoff and also delay the time at which runoff occurs, resulting in decreased stress on sewer systems at peak flow periods.

1 2 3 4

1 Evapotranspiration

2 Direct Runoff

3 Media Pour Space Uptake

4 Underflow

URBAN AGRICULTURE Using green roofs as the site for an urban agriculture project can reduce a community’s urban footprint through the creation of a local food system. These projects can serve as a source of community empowerment, give increased feelings of self–reliance, and improve levels of nutrition.

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SANCTUARY FOR WILDLIFE Some wildlife can be sustained by green roofs, although they are not intended to be replacements for true natural areas. Rather, they can be part of a system to complement green corridors and wildlife habitats within an urban setting. In highly populated areas, they could even represent island habitats, or better yet, stepping stones for wildlife movement. Even in densely populated areas, beneficial insects, bees, butterflies and birds can be attracted to green roofs. Native plant selections usually fare better in these instances since they have evolved together with the animals that depend on them for food, shelter and cover.

NOISE REDUCTION Green roofs have excellent noise attenuation, especially for low frequency sounds. An extensive green roof can reduce sound from outside by 40 decibels, while an intensive one can reduce sound by 46â&#x20AC;&#x201C;50 decibels.

AESTHETIC IMPROVEMENT Urban greening has long been promoted as an easy and effective strategy for beautifying the built environment and increasing investment opportunity.

Compared with other emerging green technologies that offer singular benefits, the installation of a green roof affords costâ&#x20AC;&#x201C;saving and environmental benefits in many areas

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GREEN FOR BETTER CITIES

LEARN MORE

Use the Green Sky Calculator App to learn saving and incentives.

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OUR GREEN SKY CALCULATOR A TOOL FOR HELPING PEOPLE LEARN THE FINANCIAL BENEFITS OF GREEN ROOFING. The Green Sky Calculator is a sleek and intuitive green savings that allows user to calculate and compare savings to other cities have incentives. This helps you to learn and realize where your stands in regards to green roof savings, policies, and incentives. currently available on the iPhone.

app that city It is

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FOUR STEPS TILL THE RESULTS STEP ONE

STEP TWO

Enter the address to find your roof.

Answer some questions and let us know more about your green roof.

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STEP TH REE

Choose what kind of roof you wish to install.

STEP FOUR

Get fast estimates!

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ADDITIONAL FUNCTIONALITY REVI EW GREEN ROOF TYPES

COMPARE WITH OTHER CITI ES

Tap the question mark on the top right to compare green roof types.

Compare savings between your city and others.

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SEE INCENTIVE DETAI LS

SAVE RESULTS

Tap on the “info” icon to see further details.

Easily save your search for the future reference.

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GET IN TOUCH If your local government doesnâ&#x20AC;&#x2122;t provide incentives, send an email to your local department of planning or environment to see what â&#x20AC;&#x2122;s available. To explore getting a green roof incentive law passed in your area, contact Green Roofs for Health Cities for some model policies.

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SPREAD THE WORLD The more people learn about green roof systems, the better! If the demand for them is high, your local goverment will be more likely to respond. Share your results on social media, and encourage people talk about it! The Green Sky Calculator app is now available in app store for iPhone. To learn more about Green Sky Calculator, please visit our website at www.green-sky.org.

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DO IT YOURSELF

This Green Roof Kit is a fun way to learn about green roof structure.

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OUR GREEN ROOF KIT AN EASY WAY TO LEARN HOW TO MAKE A DESKTOP MINIATURE GREEN ROOF. You might think a green roof system is difficult to install. This miniature Green Roof Kit will demonstrate how simple it is to construct a green roof and help make the world a greener place! Green Roof Kit provides samples of all of the pieces you need to get started. It includes a waterproof sheet, protection mat, drainage board, filter fabric, a bag of soil and plants. It's now available on your online store.

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Mini Green Roof Kit.

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Everything you need to build a mini green roof.

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GREEN FOR BETTER CITIES

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