An Introduction to

Green Roofs

Mark OstendorfMS Environmental Sciences

LEED Green Associatehttp://www.linkedin.com/in/mostendorf

Background• 2008, BGS emphasizing Sustainability

– MSSU, Joplin, MO

• 2012, MS Environmental Sciences

– SIUE, Edwardsville, IL

– SIUE G.R.E.E.N. Member

(Green Roof Environmental Evaluation Network)

– Thesis: Evaluating the Environmental Benefits of Green Retaining Walls

• 2012-2014, Living Wall Company– Product Manager

– Worked on numerous green wall projects

• LEED Green Associate

Overview1. What is a green roof?

1. Composition of a Green Roof

2. Types of Green Roofs

2. Advantages of green roofs1. Stormwater Benefits

2. Other Benefits

3. Feasibility for green roofs at schools1. Defining Goals and Purpose

2. Budget, for installation and maintenance

3. Selecting the correct green roof system

4. Green Roof Examples around the St. Louis region1. St. Louis Zoo

2. SIU Edwardsville

3. Shaw Nature Reserve

4. NGRREC

Living Architecture

Old Concept, New Technology• Hanging Gardens of BabylonOne of the Seven Wonders of the Ancient World

– Green Roofs– Living Walls

• Sod Homes– Europe– North America

• Modern Green Roofs – Germany in the 1970s– Established building standards (see FLL)– Becoming popular in North America

• Philadelphia• Chicago• Washington, D.C.• New York• Seattle• Vancouver

Modern Green Roofs

What is a green roof?

• A building roof that is covered with vegetation, which is planted into engineered growth medium

– Rooftop Garden

– Living Roof

– Vegetated Roof

– Eco-Roof

– Nature Roof

How does a green roof work?

← Vegetation

← Soil or Growing Medium

← Root Reinforcement Mat

← Water Storage/Drainage

← Root Barrier

← Roof Membrane

← Roof Structure

Built-in-place system

Variable Green Roof Systems

Modular System

SIUe Student Success Center

What is ‘engineered’ growth

medium?Not really soil…too heavy, too much organic stuff

• Green Roofs

>20 lbs per sq ft, saturated

• Less organic material– Increases longevity of ‘soil’

– Organic material degrades

– Decreases weeds

• Engineered media holds more moisture

What grows on a green roof?

Characteristics• Hardy• Drought-tolerant • Shallow root

systems• Sun-tolerant

Types• Groundcovers• Succulents• Grasses• Native Plants• Shrubs• Small Trees• Vegetables

St. Louis ZooGrasses, Natives, Trees

Succulent Groundcover

Wheat-covered Green Roof

Types of Green RoofsExtensive Intensive

Extensive Green Roofs

• Growing Medium<6 in depth

• Vegetation: – Typically Sedum

(Stonecrops)

• Low Maintenance

• Little to no structural reinforcement– 15-45 lbs per sq ft

• Designed for no or infrequent irrigation

• Easier to install on existing buildings

• $10-15 per sf, installed

Ford Factory, Sedum-covered Green Roof

Sedum: Drought-tolerant, Succulent, Shallow Roots

• Growing Medium>6 in depth

• Vegetation:– Sedum, Grasses, Native plants,

shrubs, small trees

• Higher Maintenance

• Requires careful engineering– 50+ lbs per sq ft

• Requires irrigation

• Easier to install on newbuildings

• $25+ per sf, installed

Intensive Green Roofs

Green Roof, Washington, D.C.

Shaw Nature Reserve, Native Green Roof

Why install green roofs?

Benefits of Green Infrastructure

Why install green roofs?

• Stormwater Benefits– Stormwater Runoff, Flash Flooding– Water Pollution

• Other benefits– Urban Heat Island– Air Pollution– Biodiversity (plants, insects, birds)– Combat “Nature Deficit Disorder”– Grow food!– Educational Benefits

• Outdoor Classroom

Modified from http://www.epa.gov/hiri/resources/pdf/BasicsCompendium.pdf

Stormwater Benefits

Natural Hydrology

Stormwater Benefits

Altered Hydrology

Rooftops

RoadsParking Lots

Compacted Soils

Stormwater Benefits

Surface Runoff and Pollution• Urban runoff can impair water quality– Road grime washes into streams, often

untreated!

– Unsafe to swim or fish

– Stormwater from warm urban areas can cause stream temperatures to RISE

– Impact fish, insects, and plants

OLDER SOLUTIONS:

Quickly Drain the Stormwater

• Channelize Waterways

– River Des Peres

• Stormwater Sewers– Combined Wastewater & Stormwater sewers

PROBLEMS:

• Concentrated Pollution channels

• Biodiversity Loss

• Combined Sewer Overflows

• Basement Backups

Down the drain…

Plants do an amazing job handling rainwater!

– They intercept rainfall

– Plants can store water for use during dry conditions

– Plants can uptake, use, and evapotranspire water

– Plants also uptake, store, and remediatepollution

– Leaves, stems, and roots slow stormwater runoff

Cactus, on a green roof, stores water

SOLUTIONS:

• Retention/detention basins

• Constructed wetlands

• Grass swales

• Rain Gardens

PROBLEMS:

• Lack of space

• High property value

• Cost of implementing BMPs

Re-establish natural hydrology

Stormwater Benefits

Utilizing Plants

Addressing stormwater with green roofs

• Stormwater Runoff Reduction– 100% during light precipitation

– Intensive 65-94% runoff reduction

– Extensive 45-90% runoff reduction

– Green roof slope decreases retention

• Delay runoff– Delay runoff by 1 to 10 minutes

– Delaying flash flooding

– Store water for irrigation

• Cisterns, rain barrels

Sloped Green Roof, California

SIUe

Other Benefits: Urban Heat Island Effect

Up to 5-7 degrees hotter!

CONTRIBUTORS– Roads, parking lots, roof tops– Reduced vegetation– Reduced blue space– Reduced wind– Anthropogenic heat sources

• Industry, Automobiles, HVAC, etc.

GREEN ROOFS– Reflect more sunlight than blacktop roofs– Shade the building roof– Provide extra insulation

• Reduce AC use, minimizing cost and pollutionModified from http://www.epa.gov/hiri/resources/pdf/BasicsCompendium.pdf

Temperatures in urban areas are generally higher than temperatures in surrounding rural areas.

COST BENEFIT ANALYSIS: Green Roof vs Black Roof

• The longevity of green roofs = savings factor

• Installation and maintenance = cost factor

• Fewer floors a building = greater energy savings

• More surface area= greater stormwater management savings

• Cost savings will increase as:– Stormwater regulations become more stringent and

– Green roofs become more acceptable as mitigation measures

Other Benefits: Economic

Other Benefits

• Air Pollution

• Biodiversity (plants, insects, birds)

• Combat “Nature Deficit Disorder”

• Urban Agriculture

• Educational Benefits

– Outdoor Classroom

https://www.flickr.com/photos/sbwoodside/with/501104668

Canada Goose Nesting

Feasibility of green roofs at

schools

1. Define Goals/Purpose

2. Budget, for installation and maintenance

3. Green roof selection

Feasibility: Goals and Purpose1. Reduce Stormwater Runoff

1. Intensive=75% retention

2. Extensive=45% retention

3. Stormwater/sewer fees or incentives

4. Plants affect performance

2. Improve water and air quality1. Plants Selected affect performance

3. Increase biodiversity1. Extensive < intensive

2. Native Plants

3. Pollinating insects, nesting birds

4. Outdoor classroom1. Will it be accessible or at least viewable?

2. Outdoor Lab, or just outdoor learning

3. Safety!

5. Grow food1. Another opportunity to learn about gardening

Feasibility: Budget

1. Installing Green Roofs1. Intensive= $25+ per sq ft

2. Extensive= $10-15 per sq ft

3. Stormwater/sewer rebates

4. Gov’t incentives

2. Remember the maintenance1. Extensive green roofs are cheaper to maintain!

2. $0.75–$1.50 per square foot, per year

3. Cost/Benefit1. Outdoor Classroom

1. Vs field trip costs

2. Design to last 2x longer than a conventional roof

3. Reduced Stormwater Fees

4. Energy cost reduction

Feasibility: Select Green Roof

System1. Consult Engineers

1. For new construction

2. For retrofits

2. Consult Horticulturists

3. Choose a product that matches your goals and your budget

4. Green Roof Installers1. Regional/Local

2. Provide Maintenance Expertise

Places to see Green Roofs

A few from the St. Louis area

Places to see Green Roofs

St. Louis Zoo, River’s Edge Exhibit

Places to see Green Roofs

Southern Illinois University Edwardsville,

Student Success Center

Numerous Green Roof and Green Wall Projects

Places to see Green Roofs

Shaw Nature Reserve, Near Bascom House

Places to see Green RoofsNational Great Rivers Research and Educational Center

Alton, IL

Resources

• Green Roofs, EPA.http://www.epa.gov/heatisland/mitigation/greenroofs.htm

• Green Infrastructure, EPAhttp://water.epa.gov/infrastructure/greeninfrastructure/index.cfm

• Low Impact Development, EPAhttp://water.epa.gov/polwaste/green/index.cfm• Green Roofs 101, GreenRoofs.comhttp://www.greenroofs.com/Greenroofs101/index.html

• Cost Benefit Analysis, Green Roofs, GSAhttp://www.gsa.gov/portal/mediaId/167839/fileName/Cost_Benefit_Analysis.action

• Green Roof Resources (for Teachers)http://teachers.egfi-k12.org/green-roof-resources/