 |
|
Growing green roofs
September 04, 2009EAST LANSING, MI-One way to maximize the eco-friendly factor of a structure is to include a green roof-and this doesn't refer to the paint color. "Greening" a roof, or covering a roof with vegetation, is gaining popularity in North America, where the number of green roofs increased 30% from 2006 to 2007. Benefits of green roofs include improved storm water management, energy conservation, reduced noise and air pollution, improved biodiversity, and even a better return on investment than traditional roofing.
But a healthy roof requires the selection of a species that can survive extreme climates and propagate easily to reduce erosion and weed growth. Kristin L. Getter of Michigan State University's Department of Horticulture led a study to determine the effect of the growing medium's depth on the success of green roofs. The research study, published in a recent issue of HortScience, focused on Sedum, a variety of succulent known for its drought tolerance.
Plots were constructed using the drainage mats and waterproofing systems typical of green roofs, but the growing material varied in depth from 4 cm, 7 cm, and 10 cm. Twelve species of Sedum were planted, fertilized, and watered once. The moisture of the growing material was measured at random times each week. Measurements of chlorophyll fluorescence were taken to monitor the health of the plants during a variety of environmental conditions.
Plants were monitored over the course of four years. Since the average lifespan of the inorganic components of a green roof is about 45 years, the researchers determined that it was important to study the longevity of the plants. The study found that the shallowest plot had the lowest moisture levels on average and dried the fastest after a rain. At the 4-cm depth, four species failed to exhibit significant growth over the 4-year period.
Five species showed no or little growth at the 7-cm depth, and six species showed no or little growth at a depth of 10 cm. Some species declined over the 4-year period at the varying depths. The remaining plants that flourished were the same species for all three depths (S. floriferum, S. sexangulare, S. spurium 'John Creech', and S. stefco). The 4-cm depth also included two other species (S. hispanicum and S. reflexum 'Blue Spruce').
Furthermore, the results indicate that, for the surviving and most-abundant species, there is no benefit to depths greater than 7 cm, which would appear to be good news considering shallow depths are more desirable because they make for lighter roof loads. "However, at deeper depths, these plants would likely be healthier, contain greater biomass, and be less susceptible to adverse environmental conditions. This study shows the importance of growing medium depth for plant performance and demonstrates the need for long-term evaluation of species for use in this green practice", concluded the researchers.
American Society for Horticultural Science
Plants were monitored over the course of four years. Since the average lifespan of the inorganic components of a green roof is about 45 years, the researchers determined that it was important to study the longevity of the plants. The study found that the shallowest plot had the lowest moisture levels on average and dried the fastest after a rain. At the 4-cm depth, four species failed to exhibit significant growth over the 4-year period.
Five species showed no or little growth at the 7-cm depth, and six species showed no or little growth at a depth of 10 cm. Some species declined over the 4-year period at the varying depths. The remaining plants that flourished were the same species for all three depths (S. floriferum, S. sexangulare, S. spurium 'John Creech', and S. stefco). The 4-cm depth also included two other species (S. hispanicum and S. reflexum 'Blue Spruce').
Furthermore, the results indicate that, for the surviving and most-abundant species, there is no benefit to depths greater than 7 cm, which would appear to be good news considering shallow depths are more desirable because they make for lighter roof loads. "However, at deeper depths, these plants would likely be healthier, contain greater biomass, and be less susceptible to adverse environmental conditions. This study shows the importance of growing medium depth for plant performance and demonstrates the need for long-term evaluation of species for use in this green practice", concluded the researchers.
American Society for Horticultural Science
Reducing greenhouse gases may not be enough to slow climate change
Because land use changes are responsible for 50 percent of warming in the US, policymakers need to address the influence of global deforestation and urbanization on climate change, in addition to greenhouse gas emissions.
'Green' roofs may help put lid on global warming
"Green" roofs, those increasingly popular urban rooftops covered with plants, could help fight global warming, scientists in Michigan are reporting.
Green Roofs Differ in Building Cooling, Water Handling Capabilities
The first study to compare the performance of different types of green roofs has been completed by the Lady Bird Johnson Wildflower Center at The University of Texas at Austin and suggests that buyers shouldn't assume these roofs are created equal.
More Green Roofs Current Events and Green Roofs News Articles
 |
Planting Green Roofs and Living Walls by Nigel Dunnett (Author), Noël Kingsbury (Author) The latest techniques for planting roofs and walls to enhance our buildings and benefit the environment. The green roof industry is booming and the technology changing fast as professionals respond to the unique challenges of each new planting. In this comprehensively updated, fully revised edition of their authoritative reference, Nigel Dunnett and Noël Kingsbury reveal the very latest techniques, materials, and plants, and showcase some spectacular new case studies for the non-professional. Green roofs and walls reduce pollution and runoff, help insulate and reduce the maintenance needs of buildings, contribute to biodiversity, and provide habitats for wildlife. In addition to all this, they are attractive to look at and enhance the quality of life of residents. In Planting Green Roofs... |
 |
Green Roof Plants: A Resource and Planting Guide by Edmund C. Snodgrass (Author), Lucie L. Snodgrass (Author) Green roofs have gone from horticultural curiosity to booming growth industry in urban and suburban settings alike—primarily because their environmental benefits are now beyond dispute. Concise, accurate, and easy to use, this is the first reference devoted to the drought-tolerant plants most likely to succeed in this environment. The text covers moisture needs, heat tolerance, hardiness, bloom color, foliage characteristics, and height of 350 species and cultivars. Green Roof Plants is destined to become an indispensable practical reference guide for architects, landscape designers, engineers, and environmentally conscious home gardeners. |
 |
Green Roof Construction and Maintenance (GreenSource Books) (Mcgraw-Hill's Greensource) by Kelly Luckett (Author) A Complete Guide to Building and Maintaining Green Roofs Written by an industry expert in green roof design and installation, this GreenSource book presents all of the information you need to skillfully design, construct, and maintain green roofs. You will find a wealth of practical details gathered through real-world implementations and independent research. Green Roof Construction and Maintenance explains how to design a green roof, plan for irrigation and drainage, select and place soil and plants, and maintain the entire setup. The book also discusses return on investment, LEED design specifications, and the myriad short- and long-term environmental benefits of green roofs. Filled with step-by-step illustrations and full-color photographs, this is a valuable, hands-on guide... |
 |
Green Roofs in Sustainable Landscape Design by Steven L. Cantor (Author), Steven Peck (Foreword) A popular design trend, green roofs make private and public buildings inviting and environmentally friendly. Green roofs offer many aesthetic benefits as well as environmental ones. Landscape architect Steven Cantor gives the basic terminology of green roof design, defines the green roof types, reviews materials of construction and methods of installation, and explores sixty projects in detail, identifying the design process, the program for the project, and the specific application of green roof design and technology. He gives design professionals and students a thorough introduction to the applications and impacts of green roofs on the built environment and shows how they can be integrated into contemporary buildings as well as existing structures. Green... |
 |
Green Roofs: Ecological Design And Construction by Earth Pledge Foundation (Author), Leslie Hoffman (Foreword), William McDonough (Foreword) -- Cooling cities -- Reducing energy demand -- Containing water runoff -- Preserving wildlife habitat -- Enhancing urban well-being These are a few of the many reasons why green roofs are sprouting in cities around the world. Examine possibilities for city-wide green roof development through 335 color photographs, 40 case studies of exemplary green roof building projects, and 7 municipal case studies describing green roofs in Berlin, Tokyo, London, Portland, Chicago, Toronto, and New York. This book details the ecological benefits, technical requirements, architectural history, and design possibilities of vegetated rooftops. Green Roofs: Ecological Design and Construction will inform and inspire communities, designers, building owners, and local leaders by showcasing the environmental and... |
 |
Green Roof Systems : A Guide to the Planning, Design and Construction of Building Over Structure by Susan Weiler (Author), Katrin Scholz-Barth (Author) Green Roof Systems goes beyond the fashionable green roof movement and provides solid information on building accessible space, often as important public space, over structure. It offers brief coverage of the entire process, including planning and collaboration, and focuses on the technical aspects of these roof systems, their components, and their applications. |
 |
Award Winning Green Roof Designs (Schiffer Book) by Steven Peck (Author) Over 100 beautiful, informative photos display the green roofs technology that is quickly becoming a fundamental element of the emerging practice of living architecture. The award-winning roof designs displayed and described, for private homes, businesses, and public spaces alike, integrate natural and artificial systems, resulting in healthier, more sustainable buildings and communities. Green roofs have the capacity to deliver multiple public and private benefits. The projects depicted and discussed cover a wide geographic range from Manitoba to Florida, stretching from the mid-Atlantic coast to the Pacific. The projects are almost exclusively the product of multi-disciplinary, collaborative design processes. Details about the plants used, growing media, drainage and irrigation... |
 |
Green Roof: A Case Study: Michael Van Valkenburgh Associates' Design For the Headquarters of the American Society of Landscape Architects by Christian Werthmann (Author) The benefits of green roofs are many: longer roof lifespan, greater sound insulation, reduced heating and cooling system needs, and a cutback in storm water runoff. Green roofs decrease carbon dioxide and increase oxygen in cities, making them cooler in the process and reversing the so-called 'urban heat island effect.' In short, green roofs are the great green hope of many environmentalists, politicians, and architects interested in more efficient and environmentally aware buildings. From a design standpoint, however, there is less consensus. While some see the roof garden as a visual statement using plants, geometric lines, and sculptural elements, others believe concerns for sustainability should outweigh visual appeal. A green roof that combines aesthetics and mechanics has become the... |
 |
Building Green, New Edition: A Complete How-To Guide to Alternative Building Methods Earth Plaster * Straw Bale * Cordwood * Cob * Living Roofs (Building Green: A Complete How-To Guide to Alternative) by Clarke Snell (Author), Tim Callahan (Author) The best-selling and highly regarded reference to sustainable construction gets an update! It’s refreshed with a completely revised introduction, a bright new cover, and extensive online resource tie-ins. Plus, it’s now printed on recycled paper with agri-based inks, so it’s greener than ever! This groundbreaking book doesn’t just tell you about “green” house-building techniques: it actually shows you, with more than 1,200 step-by-step photographs that follow the actual erection of an alternative building from site selection to final-touch interior details. Readers will get a clear sense of the real world challenges as Snell and Callahan create a lovely country cottage using four methods: straw bale, cob,... |
 |
Roof Gardens: History, Design, and Construction (Norton Books for Architects & Designers) by Theodore H. Osmundson (Author) A lavishly illustrated study of gardens built on the roofs of buildings. The first comprehensive hook in English about roof gardens, this survey includes a history of roof gardens, which date back to the hanging gardens of Nebuchadnezzar; summarizes contemporary design principles; details the techniques used in constructing durable and safe gardens; and gives guidelines for the selection of plants, planting procedures, and maintenance Sixty major projects from around the world are shown in color making the hook an important resource for designers and planners. |
| © 2009 BrightSurf.com |