Sustainable Solutions (Green Building applications)

Green Screen

By integrating more trees and photosynthesizing plants within the fabric of our existing cities, we harness the power of plants to absorb carbon from the atmosphere. The surface area of buildings multiplies the ground footprint of the city many times over, making vertical gardening and the integration of growing walls into our buildings an interesting practical solution. The roofscape of most cities is an area that is often forgotten but that could easily be used for the application of green technologies beneficial to all. Greenscreen is a type of metal structure that can be attached to existing walls or used to create freestanding growing walls.

Wind Belt and Green Roof
Wind belts are a recent technology which harness the power of the wind to generate electricity. They are relatively inexpensive and suitable for both developed and developing countries and are the first wind technology not to employ turbines: “About the size of a cell phone, the final Windbelt prototype employs a taut membrane that, when air passes over it, vibrates between metal coils to generate electricity.”

Wind belts could be used on the facades and roofs of existing buildings as a sculptural element, taking advantage of the building envelope as an available surface upon which to attach. Trees may be planted on the roof by using either planters or by using a new Japanese soil substitute, Pafcal, which is much lighter than earth.

Wind belts can also be attached to functional structures such as canopies which are normally used to protect the building entry from rain.

Roof Pond

Roof ponds can be used for cooling in areas that are warm and not very humid. This technology has a lot of potential, but has been underused to date because of a fear of leakage on the part of architects and clients, however, if properly detailed it is a promising strategy and can help to reduce the heat island effect in cities. Water is placed between two layers of insulating material. The area covered with water should be 85% to 100% of floor area in places with winter temperatures between 25 and 35 degrees Fahrenheit (-4 to +2 Celsius) and 60% to 90% of floor area in places with winter temperatures between 35 and 45 degrees Fahrenheit ( +2 to +7 degrees Celsius). Average pond depth is between 3 and 6 inches. Insulating panels cover the roof and are opened during the day in the winter to absorb the heat of the sun, and at night, the panels are closed, allowing heat to radiate to the building’s interior. In the summer, the process is reversed.

Roof Spray

This is another method for cooling which could be employed in a retrofit of existing buildings. It can be used in combination with the roof pond, or independently with the water being stored in a tank. Here water is cooled by spray at night, via evaporation and night sky radiation, and then stored for use during the day in the building’s cooling system.

Water Wall , Water Collection and Solar Pipe

It is well known that electricity can be generated from fast moving water. Here, we propose that a water wall be added to a blank facade on an existing building as a means of generating electricity. Water can be collected via a system of gutters on the building, and then can be piped and recycled to generate the necessary flow. This water can also be used to flush toilets and for other non-potable applications. In addition, the water provides cooling to the building’s inhabitants.
The roof in this scheme is envisioned as a space in which the entire surface area is covered by solar coils. This is a recent development: “Solyndra’s panels employ cylindrical modules which capture sunlight across a 360-degree photovoltaic surface capable of converting direct, diffuse and reflected sunlight into electricity. This self-tracking design allows Solyndra’s PV systems to capture significantly more sunlight than traditional flat-surfaced solar panels...”

Why a Green Roof? Estimated Carbon Absorptive Power of Trees
The amount of carbon dioxide or greenhouse gas emissions that a tree absorbs is not the same for all trees. An oak tree in the Midwest absorbs a different amount of CO2 than a palm tree in Florida or a pine tree in Canada. The absorbtion of carbon dioxide of each tree is different depending on its size, how old the tree is and the type of climate where it grows. However, it is estimated that one tree removes an average of 3 kilograms of CO2 from the air in one year.


Lightweight soil substitutes such as Pafcal are being developed which will allow for roof planting without the heavy loads associated with soil.  Green screens have been developed which can allow vertical gardens to grow up the facades of existing buildings. Urban farming, which could take place in buildings within the city limits, thus drastically reducing the travel distance for foodstuffs, is being explored. Indoor farming does not require fossil fuels for plowing fields and driving harvests to market, nor does it require fertilizer or pesticides, and plants can be grown 24 hours a day. Indeed, “a 30 story farm that covered a city block could feed 50,000 people year round” (Fischitti, 74). Solar modules are being designed that can be attached to light fixtures,  or which come in rounded tubes and are able to collect more energy from the sun than traditional solar panels, converting direct, diffuse, and reflected sunlight into power.  So it would appear that Socolow and Pacala are correct in their assumption that all or most of the technology needed to reduce carbon emissions to stabilized levels already exists.

The City as Retrofit: Clip Ons to the Rescue!

What might it look like to see all of these technologies together? There are obviously many things which have not been discussed here that may be applied both within and outside the building envelope, and there are still many issues to research and explore. However, I thought it useful to conclude with an image which visualizes the clip-on city infrastructure at work. Below you see a piece of an existing city to which we have applied some of the technologies discussed above. Large scale urban farming which takes place indoors and on large expanses of roof, green screens to let plants to climb the vertical surfaces of the city, trees which are now able to grow on the city roofscape. Roof ponds and artificial waterfalls for cooling and electrical generation. Solar and wind devices which form sculptural elements in the city, performing a function as well as having an aesthetic. Ports for plug-in electric vehicles which gather energy from photovoltaics. Solar panels incorporated
into street poles, and vertical wind turbines which form a rhythm in the streetscape. Bicycle lanes, room for walking and the incorporation of still more trees. It’s only a diagram, but perhaps the current dilemma can provide an opportunity to rethink and retool our existing way of life. Perhaps utopia is now.

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