Green Roofs – Benefits & Challenges

Green Roofs – Benefits & Challenges

Course Outline

This three-hour online course discusses the economic, environmental, and societal benefits of green roofs which help reduce the heat island effect of overdeveloped cities. The main benefits of green roof installation – stormwater management, energy saving, air quality and quality of life improvements, and aesthetics are considered. Challenges such as building structural requirements, leak and leak detection, and wind scour are also considered.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

Course topics covered include:

Background & history of installations;
Biodiversity & habitat improvements;
Urban heat island problems;
Energy savings;
Air quality improvements;
Cost Benefit analysis;
Installation & construction;
Practices used to maximize the benefits; and
References and sources for the topics covered.

Intended Audience

This course is intended for civil engineers, project managers, planners and building managers

Benefit to Attendees

The student will better understand the benefits and challenges of green roofs installed on urban buildings. The benefits are numerous; stormwater management and mitigating urban heat island problems are the prime movers. Stormwater management is often the main reason for green roofs. Some cities still have combined sanitary and storm drain systems which can cause overflow and release untreated sewage when overwhelmed by large storms. These untreated releases present risks to humans and the environment.

Course Introduction

Accelerated land development and land use changes caused from increased urbanization have increased roof areas and pavement surfaces and coupled with clearing of woodland and grassland have increased erosion speeded up runoff. Large undeveloped areas once available for rainfall infiltration have been lost. Vegetation removal further accelerates erosion and siltation.
Green roofs in urban environments or urban heat islands are to regain the same benefits plants provide in natural undeveloped areas: reduce the sewer overflows especially from combined sewers and reduce the higher temperatures in cities. Green roofs are sometimes referred to as ‘vegetative roofs’ or ‘eco-roofs. They consist of waterproofing membranes, soil layers and vegetation, and drainage layers to store and direct runoff. The amount of vegetation depends on the scope of the green roof: extensive (min) or intensive (deeper soil layers and larger vegetation).

Extensive Green Roofs Intensive Green Roofs

Lightweight: 13-50 lbs./sf Heavier weights: 50 + lbs./sf
Low depth growth media: 2-6 inches Deeper >6-15 inches and deeper
Low growing plants: 1-24inches Larger plants, trees, scrubs
Less variety of plants More variety of plants
Usually non-accessible Designed for live load of people
Low water requirements Irrigation may be necessary
Low maintenance Higher maintenance
Slopes up to 30 degrees Relatively flat

Course Content

This course is based on the Introduction and Chapters 1 - 4 of the US GSA Report, “The Benefits and Challenges of Green Roofs on Public and Commercial Buildings”, (2011 Edition 98 pages), PDF file.

The Benefits and Challenges of Green Roofs on Public and Commercial Buildings

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

Green roof technology helps to mitigate some of the negative effects of urban land development by reintroducing a natural landscape into urban areas. They provide many economic, environmental and social benefits to cities. Among the factors to be considered are the buildings’ structure requirements, leak and leak detection, plant establishment, root penetration, biodegradation and wind scour. This course also considers the benefits wetlands provide for controlling soil erosion and protecting water quality.

References

For additional technical information related to this subject, please refer to:

http://www.greenroofs.com
Green roofs for healthy cities.

http://www.nrel.gov/docs/fy04osti/36060.pdf
US Dept. of Energy – Green roof primer.

http://www.epa.gov/heatisland/resources/pdf/GreenRoofsCompendium.pdf
US EPA Green roofs report.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.