Market Intelligence

Green & Sustainable Construction

Greenroofs as High Performance Design

Increasingly, high performance buildings, green design practices, and sustainable technologies are becoming major architectural influences and are now setting standards within the international construction industry. Encouraged by successful programs such as the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) Green Building Rating System™, the benchmark for the design, construction and operation of our built environment has been raised substantially from just even a decade ago.

Amidst growing media interest and demand from public and private sectors, multidisciplinary professionals - from architects to environmental engineers, city planners to landscape architects and beyond - are redefining sustainability in the context of building design. We’re examining our environmental impacts on the Earth from a more integrated, holistic approach and using technologies which encourage energy efficient and environmentally friendly building envelopes, including the ubiquitous “fifth façade” – the rooftop.

Greenroofs are fast becoming green staples of chic sustainability in mainstream architecture and high performance building. Greenroofs are vibrant and exciting alternatives to the average unused, hot, and often downright ugly black tar or concrete roofs that we see covering the world. So what is a greenroof?

Greenroof at Life Expression Wellness Center, Sugarloaf, PA
©Roofscapes, Inc. Used by permission; all rights reserved.

Greenroofs can be as simple as vegetated roof covers or more elaborate roof gardens constructed atop and across a roof deck, with engineered soil and plants taking the place of bare membrane, gravel ballast, shingles or tiles. It is important to note that greenroofs are engineered systems using proven waterproofing and other roofing technology developed, tested and implemented in Germany, now being specified globally. And remember that greenroofs are living roofs in that they contrast starkly to otherwise barren roofs!

Imagine looking down from an airplane with a bird’s eye perspective, and instead of seeing huge expanses of unattractive, unproductive barren roofs imposing themselves on the natural landscape, you see moving strands of flowering plants that appear to blend into the environment as naturalistic meadow scenes or stand out as highly designed gardens meant for human recreation.

There are two main types of greenroofs – extensive or intensive - although a greenroof is often designed with features of both, depending on factors such as desired function, weight loading capacity, slope and budget. The number of layers and the layer placement vary from system to system and greenroof type, but at the very least all greenroofs include from the roof deck up:

  • Waterproofing: single to multi-ply layers with root repellent barrier if the material is organic in nature
  • Drainage: granular or geocomposite layer with filter fabric on top or modular
  • Growth media: extremely lightweight, highly inorganic engineered soil substrate
  • Vegetation: drought tolerant Alpine type plants – succulents, flowering herbs, some bulbs, grasses and mosses – which also need to be wind, frost, heat tolerant, self regenerative and low maintenance.

The beauty and promise of sustainable architecture and the epitome of sustainable design lies in the integration of building roof, skin, interior, and site. The greatest potential of greenroofs lies in their capacity to cover impervious roof surfaces with living, breathing, permeable plant material. And when considered as one layer of a green building strategy, greenroofs can reduce energy use and costs, cleanse the air and water, utilize local and recycled materials, create jobs, extend the life of the roof, improve aesthetics, and carve out green corridors for wildlife while providing a psychological and physical respite.

Greenroofs deliver much more to the urban landscape than just the obvious ecological, economic and aesthetic attributes of stormwater management, temperature and energy reduction, and provision of additional greenspace.

Greenroofs are healthy, sustainable and regenerative roof landscapes that can help protect our environment by diminishing developmental impacts on our communities, and are quickly gaining deserved recognition in the palette of today’s ecological designers and in the bottom line of government and business leaders.

Schwab Rehabilitation Hospital Rooftop Garden, Chicago, IL
Photo Courtesy American Hydrotech, Inc.
Intensive Greenroof Material Section Graphic Courtesy American Hydrotech, Inc.

About Greenroofs.com

Greenroofs.com is the international greenroof industry's resource and online information portal. We inform, promote and inspire through the interchange of ideas, projects, news, events, research, community and organization updates, and marketing opportunities; exclusives include Forums, contributing editor columns, guest features, and classifieds. Greenroofs.com publishes the Greenroof Directory of Manufacturers, Suppliers, Professional Services, Organizations & Green Resources; the global Greenroof Projects Database, a free online resource; and our new GreenroofsTV, a video channel devoted to greenroofs.

Linda S. Velazquez, ASLA Associate, LEED AP, is founder and publisher of Greenroofs.com and holds a Bachelor's of Landscape Architecture from the University of Georgia. Ms. Velazquez is also the principal of Sky Gardens Design and a LEED Accredited Professional who designs, consults, and presents on greenroofs nationally and internationally. She writes and reports extensively about greenroofs, including her occasional column entitled "Sky Gardens ~ Travels in Landscape Architecture" on Greenroofs.com.


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This article is an excerpt from the book Green Building: Project Planning & Estimating which can be purchased through the RSMeans Bookstore.

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