White painted roofs deflect approximately 85% of heat that touches it, lowering the surface temperature by 50 degrees; this cuts overall AC costs and carbon emissions
The coat of white paint used is specially manufactured by an 82-year old from SE California- paint is composed of tiny hollow glass balls that lay on top of a waterproof layer of recycled rubber.
If white roofs were implemented in one hundred of the largest cities, it is predicted that it would avert the production of 44 billion tons of carbon-dioxide emissions = 600 million cars for 18 years according to Lawrence Berkeley National Laboratory. (1)
It is also common for buildings to have a combination of green and white hues that reflect the sunlight, in addition to a garden complete with shrubs and various types of plants.
Albedo is a means by which the amount of sun reflected is measured. A surface that is colored black, for example, has an albedo value of 0, while a surface that is painted white and is reflective has an albedo of 1. Surfaces with other colors have albedo values between 0 and 1. Below is a diagram that expresses these values and their accompanying colors. The lower the number, the darker the color; darker roofs can increase a city’s temperature by up to 10 degrees. (2)
http://en.wikipedia.org/wiki/Cool_roof
Seattle
The Ballard Library designed by Seattle-based architect Bohlin Cywinski Jackson is an exemplar of Seattle’s Sustainable Building Policy. The Library’s green roof consists of solar panels provided by the Seattle City Light Green Power Panel. These panels capture sunlight, thereby generating energy that is recycled back into the city’s power grid. In this way, costs are reduced and carbon emissions are kept to a minimum. Some of the plants exhibited on the roof include Blue-eyed grass, Thyme, and White stonecrop. The Library is a prime example that a building can be both ecologically sound and architecturally beautiful. (3)
Chicago
In Chicago, the green wheels have already started turning, and they’ve been turning for a while.
In 2001, Joyce Coffee, the policy director in the state’s environment department, showed the successful results of the rooftop garden she had installed on the top of her headquarter building. According to her heat map, on a 70-degree day, the City Hall retained a temperature of 74 degrees while the neighboring building had a rooftop temperature of 151 degrees.
Chicago is one of the pioneering cities in the country that extensively conducted research with the EPA and embarked on a project to construct a green roof with an area of 38,800 square foot. This project serves the purpose of a test subject; it is observed and monitored so that future green roofs can be more efficient and improved.
According to Michael Berkshire, the Green Projects Administrator at City of Chicago, claims that a green roof saves $5000 annually on utility bills. Atop the City Hall building lies 20,000 herbaceous plants and additional shrubs, vines and trees.
Currently, a bill that would institute a community garden grant program at the U.S. Department of Agriculture is in consideration. (4)
The Peggy Notebaert Nature Museum also located in Chicago is an educational site where visitors experience nature firsthand. It is also one of the city’s most eco-friendly buildings with tours that stop at the rooftop. The roof, specifically, can hold an additional 40-90 pounds, including perennials and even small trees. The building set an example to urban residents that even in a metropolis, there are ways to conserve energy. (5)
Europe
In recent news, the Liljeholmstorget Galleria, a shopping center in Stockholm, Sweden was bestowed a platinum LEED environmental certificate, as the first center in Europe to achieve such an honor. Located in an urban setting, Liljeholmen exhibits the finest properties of green housing; its AC and electricity is produced by wind power, its wastes are sorted and recycled, and indoor air quality is 30% above ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) standards. The materials with which the building was constructed were all low-emission materials that released very little pollutants into the surrounding air. The most special facet of the center is of course, the green roof situated between the center and a neighboring office building. The center’s close proximity to the metro station is also extremely convenient to residents and shoppers as well as energy efficient in terms of transportation. (6)
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Sources:
(1)
White is the new ‘in’ color for roofs
Last Accessed 5.07.10
(2)
Albedo
Last Accessed 5.07.10
(3)
The Seattle Public Library
Last Accessed 5.07.10
(4)
Chicago City Hall
Last Accessed 5.07.10
(5)
Peggy Notebaert Nature Museum: Nurturing Nature in the 21st Century
Last Accessed 5.07.10
(6)
Europe’s first LEED platinum shopping centre in Stockholm
Last Accessed 5.07.10
