Why Green Roofs are more than Just about Keeping Buildings Dry

Green roofs are basically part of the ecological design movement's attempt to rethink the design and function of different parts of the building from the ground up.

Multifunction or Multi-use in the design and build process of architecture is seen by ecological designers. The idea is how to do more with less in the design and operation of a building and to optimize the building operation so that a component of the building has multiple functions.

In the case of a Green Roof, we have the possibility of a roof doing so much more than simply keeping the building wet, warm and structurally sound. At Arcosanti, this is one thing that Paolo Soleri has definitely considered in that most of the building's roofs are designed to be used and walked on.

The idea of a green roof though is the idea of actual green spaces located on the buildings and to use the roof as a key element in integrated building design and function.

Problem Existing cities use over 50 percent of their areas to sustain the automobile. Adding to this is the Urban Heat Island Effect that results from the usage of high levels of asphalt and concrete in urban areas. The result is that cities become furnaces during the hot months of the year. This only magnifies the tendency of seeing the city aesthetically and socially as a dehumanizing concrete jungle that mitigates human potential and offsetting what Paolo Soleri refers to as the Urban Effect tendency.

The Solution Current efforts to promote green building design such as in cities like Chicago that have been spearheaded by Mayor Daily have helped to introduce a idea of ecological design on a practical and tangible level helping to make cities more livable by making buildings more sustainable and attractive places to live and work. Under the leadership of the Mayor's green building program Chicago has emerged as a leading city for green development and innovation. The practical benefits from this kind of more enlightened urban planning includes money saved from not having to build man made flood control systems, the resulting reduction in water useage as well as a mitigation of the Urban Heat Island Effect.

A more far reaching and comprehensive approach could be more Arcology themed approaches in the design of urban centers, where all the features and attributes of urban life can be found under one all encompassing building envelop. Such designs could help us reduce our dependence on the car, increasing the amount of land that can used for open space and agriculture in the city to better balance the Urban Effect with the Rural Effect. One key aspect of this more futurist urban vision is that it would include the design of highly integrated architectural plans for sustainable human habitats such as roofs covered with protective membranes that allow the flowering of plants, food gardens and even small trees. Paolo Soleri has put this forward in many of his building designs including his current focus on Solare Lean Linear City.

Overall Goals By incorporating green roofs into the design of urban prototypes in sustainable design, we demonstrate: Offer a solution to make buildings more sustainable and integrated so that they can operate as models of sustainable habitat construction and operation.

Design solutions that embrace a holistic approach to urban planning, mitigates the negative aspects of modern urban development such as lack of greenspace, excessive pollution and the urban heat island effect.

1. Flood Control: Catching more water and keeping it on the roofs reduces water flows during heavy rains and this means that costs associated with erosion and flood problems are reduced both in terms of onsite costs as well as municipal costs.
2. Aesthetics: Using water to grow crops and gardens on rooftops means converting a desolate roof -scape into a Eden-like wonderland. From an aesthetic standpoint pedestrian accessible gardens might provide an eye-catching experience both for visitors, work shoppers and residents, thus increasing the "urban effect" within the ecovillage or ecologically themed project.
3. Provide a way for more self-reliance within cities for food supplies - Roofs will increasingly be valued by their ability to enable people to grow food close to the end user, minimizing transport costs while shortening supply lines and keeping resource flows closer to the consumer.

Considering Current Approaches and Technologies Rooftop garden systems are one way to reduce the amount of wastewater flows offsite. Some of these systems involved the set up of rainwater collection systems to absorb and slow water flows during extreme rains that are designed within the roof of the building. This would include creating cisterns to store the water for irrigation during dry periods. They also provide a way to make roofs of buildings look more attractive and provide a space for people to take a break from their lives in the building.

During the Ecosa Institute Seminar at Arcosanti in 2000, participants saw examples of Green Roof technologies such as that featured at American Hydrotech's website (http://www.hydrotechusa.com/). This company designs roofing systems that allow for gardens and green spaces. While American Hydrotech is primarily promoting green roofs as a way to improve aesthetics, flood control and heat build-up in urban areas, others promote a more comprehensive view. With the Arcology and Urban Permaculture movement the more ideal vision of green roofs involves a total rethink of how we build.

Sustainable design best practices such as Earthships and the Permaculture movement have had an impact because they imply a fundamental rethink of how we design habitats. However the question is can these permaculture and sustainability concepts can be applied to cities? One key consideration is promoting more self-reliance within cities for food, energy and building supplies.

Potential Practical Benefits and Advantages of Green Roofs The typical roof of the edenspace ecovillage/ecocity building will be buzzing with activity...By incorporating green roofs into the design of urban prototypes in sustainable design we can consider the following in the design of green buildings:

1. Incorporate architectural and structurally integrated solar panels into the roof membrane
2. Install Solar hot water panels that use the sun's radiation to create hot water.
3. Build Greenhouses and green roof gardens growing food on the top of the building through highly efficient and intensive growing systems.
4. Provide relaxing environment; a wonderful "edenspace" environment that people can enjoy that contributes to the quality of urban life thus increasing the potential of the urban effect to magnify human potential through the intensive and dynamic interaction of human beings within the urban environment.
5. Include rooftop swimming pools that double as heat sinks to heat and cool the buildings.
6. Set up Grey Water systems that can be used to irrigate gardens on the roof in dry periods.
7. Reduce the impact of the urban built environment on natural systems.

In this process, the idea multi-use on a practical level is demonstrated by designing roof systems that produce electricity, heat through solar, and incorporate green roof designs reduce environmental impacts as well as save money.

Future Thinking about Green Roofs as a way to make Cities more Sustainable in Agricultural Production More far-reaching ideas of designing roofs and the sides of building as intensive and highly integrated farming/food production systems, could use state of the art greenhouse growing techniques. For example a decentralized wastewater treatment system within a 21st century building could feature integrated industrial ecology/permaculture systems to a city aspiring to an Ecocity.

Richard Register's vision of the Ecocity would have rooflines dominated by greenhouses and open air green areas, "Edenspaces" brimming with vegetable gardens and enclosed and semi-enclosed landscaped relaxation spa areas. We also might be able to catch more water and keep it on the roofs reducing erosion on site while also using water to grow crops on the rooftops, converting a desolate concrete roof into a eden-like wonderland. From an aesthetic standpoint pedestrian accessible gardens might provide an eyecatching experience for visitors, workshoppers and residents, of the EdenSpace themed project thus increasing the "urban effect."

Cascading terraces within building envelopes would in such a Arcology themed system, functionally and aesthetically unify the aesthetic spaces of the community and maximize the amount of greenhouse/green roof space. Such an system of greenhouses, as part of multi-storey building, can functionally and aesthetically unify the aesthetic spaces of the community and maximize the amount of greenhouse/green roof space.

Most roofs are simply there to keep the buildings dry. Arcology implies a rethink of how we design cities. One goal is more self-reliance within cities for food supplies. A rethink of how we design cities involves more self-reliance within cities for food supplies. The eventual ideal is to promote an decentralized "district type" wastewater treatment system approach. This would be part of an integrated industrial ecology/permaculture system that would recycle waste flows within a habitat and revitalize and repurpose them back into meaningful utilization.

Vertical Farming Dickson Despommier coined the term Vertical Farm, “urban skyscraper farms” which he claims could produce food in greenhouses in a very efficient way. This could be a way to address current food production challenges that we face as we try to use conventional agricultural farming practices to feed a burgeoning human population that will soon reach 7 billion people. These agricultural systems because they are based on highly refined science and resulting technologies have the potential to be several fold more efficent than conventional agricultural systems in terms of per unit production while minimizing inputs such as water, heat, biomass and human labor in the growing process.

South China Arcology Francis Frick, while at the Department of Architecture at the University of Hong Kong helped promote and innovate the idea of urban agriculture (UA). Frick while working on his masters thesis came up with a plan for a South China Arcology. This was based on the premise that one way to increase the ability of cities to feed themselves is by installing green roofs.

SolaRoof Greenhouse Garden Richard Nelson's vision of Solar Roof Gardens is one innovative approach that could be considered in the design of an Arcology greenhouse complex. The system is a model “Living System” because it mimics the transpiration process. It does this in two main ways:

1. Soap bubbles are used to control temperature an insulator that either keeps heat out or in the greenhouse depending on the time of year.
2. Water through a liquid film that coats the outside of the inner membrane in the greenhouse to cool the bubble cavity that is building up heat during a hot time in the summertime.

By reducing heating and cooling costs for greenhouses this innovative technology has the potential to make them more competitive as compared to existing greenhouses. This is an example of an “entropy reducing” or negentropic system in the sense that it reduces waste heat and keeps the heat from the sun within the greenhouse for a longer period of time.

The Energy Apron Greenhouse Complex Planned for Arcosanti The planned Arcosanti Energy Apron Greenhouse Complex could be a way to combine many of the idea and innovative approaches mentioned in the above paragraphs. The complex would include cascading terraces along the sloping valley that comes off the Mesa where Arcosanti is located. These terraces could produce food in greenhouses in their most intense form as hydroponics design agricultural systems producing up to five times more than conventional agricultural systems.

How could Green Roofs Impact Arcosanti now? In terms of the existing Arcosanti infrastructure, an Arcology designed along these lines would function as an ecocity with rooflines dominated by greenhouses and open air green areas. These"EdenSpaces" brimming with vegetable gardens and enclosed and semi-enclosed landscaped relaxing spa areas. We also might be able to catch more water and keep it on the roofs, reducing erosion on site, while also using water to grow crops on the rooftops, converting a desolate concrete roof into a eden-like wonderland. From an aesthetic standpoint, pedestrian accessible gardens might provide an eye-catching experience for visitors, workshoppers and residents, of the EdenSpace themed project thus increasing the "Urban Effect."

Arcosanti as an Urban Laboratory is the idea of a prototype urban community that is supposed to function as a place to improve upon the function of modern urban systems through experimentation. Of course those "green" roof technologies mentioned above would be a great and compelling way to do this. Such programs are more inclined to generate economic, social and political critical mass by catching the imagination of people who come here as well as those who financially support the project through grants and donations.