The heating, cooling and lighting of our buildings accounts for 48 percent of all U.S. energy consumption. As such, building energy usage is the greatest contributor to green house gases and global warming. This will only increase as the world becomes more urbanized and the built environment represents a greater and greater portion of our environment. Stormwater runoff from buildings is also one of the greatest non-point sources of water pollution, while the manufacturer of synthetic materials used in the construction of buildings leads to hazardous waste and an increasing number of "sick" buildings. Following is a discussion of methods of constructing "green" buildings so as to promote a more sustainable environment.
Monday, May 4, 2009
Green roofs are one of the most visible ways to build more sustainable, "green" buildings. A study conducted for Toronto, Canada estimated that the installation of green roofs on buildings could: reduce the heat island effect of urban areas by 1 to 2 degrees C, reduce smog alerts in cities by 5 to 10 percent, absorb CO2 emissions from automobiles and thus reduce green house gases, reduce the energy needs of buildings for heating and air conditioning, filter storm run-off and thus reduce water pollution, and expand recreational and open space in urban areas by creating roof-top gardens.
Solar photovoltaic panels are used to convert the sun's energy into electricity. A converter is used to convert the electricity from DC to AC electricity. Any excess electricity can be stored in batteries or exported to the electrical grid and sold to the local electrical utility.
Passive solar is any means to use the heat from the sun to provide for the heating or energy needs of a building without any means of mechanical assistance. The easiest method of passive solar involves the proper siting of a building to take advantage of the sun when it is at a low horizon or angle, but to provide shading when the sun is at its highest during the hottest part of the day. Another means of passive solar design is to build the floor of a building with some type of thermal mass such as concrete that absorbs the heat - and releases the heat at night when it is cooler.
Previously, wind turbines as an energy source were typically not located on building or within urban areas. With the concern about green energy and global warming, however, new technologies have recently been developed to allow wind turbines to be built on top of buildings -- and be able to deal with the shifting wind directions typical of urban areas. These new wind turbines are omni-directional and come in sizes appropriate for individual homes and larger buildings. As such, wind turbines are increasingly a part of sustainable green buildings.
"Green" buildings can be built from a variety of new eco-friendly building materials. This includes what is perhaps the most common form of new building material -- insulated concrete forms (i.e. ICF) - as well as more exotic new building materials such insulation made from recycled jeans or recycled newspapers to replace the traditional fiberglass insulation used in homes or renewable bamboo wood floors.
Geothermal heating and cooling involves the use of ground source heat pumps to take advantage of the fairly constant ground temperature to reduce the cost of normal heat pumps to provide for heating and cooling. Wells are dug to a depth of typically 200 feet to obtain a source of air that is approximately 55 degrees year around. This reduces the need for cooling the outside air for air conditioning in the summer and for heating the outside air in the winter, and thus provides for a more efficient form of heating and air conditioning of buildings.
Another method of sustainable green building design is to incorporate means of natural ventilation and lighting into a building, and thus reduce the need for energy use. Innovative new methods of accomplishing this are solar tubes mounted on the roof of buildings that bring concentrated sunlight into buildings and often replace the need for daylight lighting within the building. Also, buildings are increasingly being built with vents on the roof that can be opened to suck the hot air out of buildings and with windows that open that can draw fresh air into buildings.
A new method of green building design is to produce a biofuel at your own home. Previously, biofuels had to be made at a larger biofuel processing facility such as a corn to ethanol plant. While some individuals had converted their automobiles to run on collected cooking grease, previously there were not commercially available biofuel processing units sized for domestic use. Recently, however, this has changed with a number of companies selling domestically sized biofuel conversion units. Above is a photo of such a domestic biofuel conversion unit to illustrate how compact in size they can be. Also, scientists are experimenting with such novel ways as growing a biofuel in vertical algae tanks. As a consequence, it is now possible to build sustainable green buildings that include units to produce biofuel - so one does not have to drive to the gas station to fill up one's automobile!
One example of a proposed sustainable "green" building is the Ecolaboratory building to be built on the 7,200 square foot P-patch in the Belltown neighborhood of downtown Seattle. Conceived by Weber Thompson, it is proposed that the main living units of the building be constructed of recycled shipping containers. All water, including black and gray water, is to be recycled for the use of residents and landscaping water needs. Residents will be able to individually control the amount of their natural ventilation by the design of what are referred to as "earth tubes." Solar hot waters panels will provide for the heating of hot water. Also providing energy for the building will be photovoltaic solar panels, biomass conversion, and even hydrogen fuel cells - to generate electricity.
To demonstrate how a sustainable home can be constructed, Duke University in conjunction with Home Depot has built a sustainable "smart home" demonstration. It has received a LEED (Leadership in Energy and Environmental Design) platinum rating, the highest level rating. It includes solar water panels for hot water heating, 18 photovoltaic solar panels that generate 3 kW of electricity, a vegetated green roof planted with sedums that are drought tolerant and capture and filter rainwater while providing roof insulation, rainwater collection for irrigation of the grass of the site, Energy Star appliances, and recycling of construction waste materials.
An example of a sustainable green building that takes advantage of natural ventilation is the Environmental Nature Center in Orange County, California.
Sunday, May 3, 2009
The proposed Independence Station building claims that, when constructed, it will be the highest rated Platinum LEED (Leadership in Energy and Environmental Design) building in the world. It will include almost all of the various approaches to green building design (green roof, photovoltaic solar panels to generate electricity, passive solar hot water heating, geothermal heating and cooling, rainwater harvesting, etc.)
The Clinton Presidential Library in Little Rock, Arkansas is the first presidential library to be designed green. When it opened, it received a silver LEED (Leadership in Energy and Environmental Design) award, but has since been upgraded to the highest award level -- i.e. a platinum award. It has a green roof with approximately 90 different types of plants, solar panels, and includes a wetlands next to it that is protected as part of the library.
One of the best examples of a building design with a green roof is the "living roof" of the newly constructed California Academy of Science in San Francisco.
The BedZED Eco-Village located in Wallington, South London, England is intended to be a zero-energy, carbon neutral community development. Opened since 2002, it is designed to house 100 families, community facilities, and office space for 100 workers. Developed by Peabody Trust in conjunction with Bioregional Development Corporation and designed by architect Bill Dunster, its homes are designed to use only 10 percent of the energy of a typical home.
The Brighton Earthship is an experimental sustainable building near Stamner Park, Brighton, East Sussex, England. Its walls are made from recycled tires and it is built semi-underground to use the insulation properties of the earth itself. It includes a windmill and passive and active solar heating, as well as geothermal heating and cooling.