Green Roof Technology By: Abby Roemer

Did you know… America's 81 million buildings consume more energy than any other sector of the U.S. economy, including transportation and industry?

Why is this fact relevant? “The Heat Island Effect” Heat radiates from city surfaces, industrial processes, and automobiles raising the immediate atmospheric temperatures. Higher temperatures create atmospheric instability, increasing chances of rainfall and severe storms. Also, high temps stir up dust, it gets trapped causing smog High energy bills Unsafe air quality Sewer system flooding and water contamination Sound penetration Over the recent few years there has been an almost frantic up rise in the concern for and awareness of the way human life marks a footprint on the environment. Many great things have resulted from our economic prosperity and development of new technology. However, where there is good, evil usually lurks not far behind, and this is evident concerning these matters. Many aspects of the build environment greatly contribute to the footprint. The footprint affects the health and stability of humans and the natural environment. Green roofing is an emerging sustainable technology in the U.S. that helps to solve issues of the urban environment, and it is a technology that anyone who chooses to implement may benefit from. Green roofs have been used domestically, commercially and by various institutional structures in a large number of European and other foreign countries for many years. Some even exceeding 25 years, such as Germany. Recently, over the past 5-10 years, select cities in the U.S., including Seattle, Chicago and Cincinnati, have chosen to promote and implement green roofs in new architectural design as well as making the addition to existing structures. Green roof technology is capable of alleviating these problems.

Presentation Preview: Defining a green roof The 2 main types Function and Benefits With that said, this presentation will inform you of the following: 1) What a green roof is, 2) the 2 main system types and how they function, and 3) the benefits that can be achieved through a green roof.

A green roof is: 2 main types: Vegetation cover on a roof surface. (Yeang, 2006) Extensive and Intensive 2 main types: In simple terms, a green roof is a rooftop covered in a layer of vegetation. The book Eco Design: A Manual for Eco Design written in 2006, explains that there are two types: Extensive and Intensive.

Type 1: Extensive Shallow depth (typically 2-4 in.) Low growing, often broad leaved plants Plants with ability to withstand harsh weather conditions Extremely low maintenance Minimal weight load An extensive green roof has a relatively shallow substrate, typically 2-4 inches in depth and the type of plants incorporated grow low and wide, often having broad leaves. Moss and grasses are commonly used as well. They are designed to be virtually maintenance free. By using hardy plants that can withstand harsh weather conditions ranging from extreme drought, to harsh winds and ice, the system requires only minimal attention. Another important characteristic of an extensive roof is that the weight in which one bears upon the structure below is minimal. This, in addition to low maintenance and low cost is mainly the reason for its popularity in comparison to the other type, intensive.

Type 2: Intensive Depth of 1ft. or more Involve high maintenance plants such as trees and shrubs Irrigation system often necessary High maintenance Considerable weight load Less common Commonly accessible by public Intensive green roofs have a much thicker substrate layer in order to accommodate the heavier, higher maintenance plants involved. Trees and shrub-like plants are commonly used and the depth of the substrate often exceeds 1 foot. This system often requires the installation of artificial irrigation. The depth of the foundation and plant weight bears a much heavier load upon the structure below and therefore must be design accordingly. Though this type of system is higher maintenance, it is the system that is capable of being utilized as a space for public recreation because the building and system is designed to bear the additional weight.

Now that you are familiar with the 2 types of systems, I’m going to cover the main functional layers of a green roof. This diagram illustrates the six basic components, and any additionally layer is optional depending on the manufacturer, who is constructing or what type of system is being implemented. 1) Plants (chosen depending on aesthetic desire and/or system types and what is desired to be achieve through their use. Plants have unique qualities) 2) A specially engineered mixture of soil, minerals and nutrients. 3) A filter layer that contains roots and soil. 4) Drainage layer that sometimes has a built in reservoir (water retained can for example be used for watering a yard or for plumbing) 5) Water proofing membrane with a root repellant. 6) Original roof structural material, or what is referred to as the roof deck. Basic System Layers

(example of a company’s system that includes additional layers)

Filters, Cleans, Cools, and releases cleaner air and water There are many environmental, economic, and psychological benefits that can be gained from a green roof. Green roofs are like sponges. They absorb rainwater and through the natural processes of evapotranspiration and photosynthesis a number of extraordinary things occur. Consider the following issues of the urban environment: -Sewer system flooding and water contamination from rainwater runoff (the water that flows off of buildings, streets, parking lots, etc. because the materials are non-porous) -and smog, which is caused by high temperatures stirring up dust high into the atmosphere, trapping greenhouse gasses and blocking sun light. A green roof absorbs rainwater and also processes the air containing chemicals. The natural processes mentioned involve the plants absorbing, filtering, cleaning, cooling and slowly releasing both air and water back into the atmosphere. Also, green roofs act as natural insulators. A research project conducted by professional engineer, Charlie Miller in 1998, revealed that temperatures on a black tar roof had a variation of 90 degrees while the variation under an almost 3-inch substrate green roof was only 18 degrees. This find shows how implementing a green roof system can save money and reduce the amount of energy use necessary to keep a building at a comfortable temperature during any season. The same engineer also found that a green roof has the potential to extend the life of a roof by 20 years or more. One last issue I will address is noise interruption. Green Roofs for Healthy Cities, a non profit organization found that a green roof with about a 5-inch substrate could reduce sound transfer by 16 times. Sound transfer is a major issue concerning individuals who work, live, or go to school in urban environments. Filters, Cleans, Cools, and releases cleaner air and water

Environmental, Economic, & Psychological Benefits: Reduced Rain Water Runoff = less chance of contaminated water or storm sewer flooding (a major issue) Cleaner Air Quality Improved Insulation = lower heating and cooling costs Water Purification Provides a Habitat for various organisms Sound Absorption Cooler air = less smog (Urban Heat Island Effect) Aesthetic Appeal Extended roof life (by 20 years or more!) Recreational Space Potential to Recycle Wastewater New Jobs (horticulture specialists,manufacturers, installation experts, etc.) This is a list of additional benefits that can be achieved from a green roof.

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