Buildings in the U.S. account for almost half of all greenhouse gas (GHG) emissions, and consume 71 percent of electricity produced by power plants. However, a 2007 survey by Harris Interactive revealed that only four percent of American adults were aware.

"The results of the survey reveal an urgent need to raise awareness with the American public about the role of buildings in climate change," said Jay Bhatt, senior vice president, Autodesk AEC Solutions.

What is an environmentally-friendly, ‘green', building? An article on the website GreenHomeBuilding.com defines it as "a design process that grows out of a connection with the natural landscape... a set of informed decisions that considers the site and materials to reduce the cost, maintenance, and energy usage of the home." Conservation is the key tenet to building an environmentally-friendly building.

Principles of environmentally-friendly homes

Smaller is better. "Nothing meets all the environmental requirements, except building smaller," said builder Cary Thompson. "It's the best thing you can do to save materials, lower costs and conserve energy."

Larger houses use much more energy to heat and cool. More materials are needed in the construction of larger houses. "A home should be just the right size for its occupants and their activities," according to the author of an article titled "Thirteen Principles of Sustainable Architecture."

Energy efficiency is important. Regardless of how a house gets its electricity, energy efficiency is a key consideration. According to EnvironmentalHouse.org, environmentally-friendly buildings "implement strategies such as airtight exteriors, increased insulation levels, shortened plumbing and duct runs, duct and plumbing insulation, high efficiency mechanical equipment, lighting and appliances, and high performance windows."

Make it water efficient. The average American uses 100 to 250 gallons of water a day. Using low water capacity toilets, installing flow restrictors on shower heads, and faucet aerators are simple ways to conserve water. Washing machines and dishwashers with Energy Star certification in the U.S., CECED AIS certified in Europe, and MEPS in Australia use much less water.

There are more innovative ways to conserve water, including using ‘gray' water from bathing, washing clothes and dishes, and bathroom sinks to water gardens and trees.  This has become especially commonplace in Australia where severe drought conditions have meant water must be used for multiple functions.  Rooftop harvested rainwater can also be used to keep the garden in good shape.  No matter where the location is, the plants and trees selected for the yard should be drought resistant, native species.

Use local and natural materials. Using local materials reduces the use of fossil fuels in transporting them, plus it reduces the cost. Natural materials are less "processed," which means less GHG emissions. As EcoHousePlan.com says, "Using local materials...plays a role in the sustainability factor."

Instead of using lumber,GreenHomeBuilding.com suggests using masonry, straw, papercrete, cob, adobe, rocks, or bags of volcanic rock. It is hard to not use lumber for the roof, but domes can be made from "materials that can be stacked." Domes have the advantage of being "more energy efficient and use less materials for the same space as a box."

Recycle materials. Using materials already in existence helps keep them out of landfills. Possible materials to use are waste wood and plastic for decks, medium density fiberboard (MDF) for doors, concrete floors, or recycled wood floors.

Build it to last. Houses need to be built to last for centuries in order to be truly sustainable. Building to last means carefully choosing materials, designing buildings for adaptation (e.g. you have children, or decide to work from home), as well as for eventual disassembly/demolition in mind (cradle-to-cradle).

Site orientation is key. Environmentally-friendly houses are designed and planned to fit the site in order to take advantage of "natural processes such as passive solar heating and effectively deal with wind patterns," according to EnvironmentalHouse.org.  Shading the house with trees helps keep it cool in the summer, plus it will block winds.

Use natural lighting. Adding windows, skylights and tubular skylights allows "natural lighting to enter the building, reducing the need for electrical lighting."

Use passive solar design. Passive solar design provides enough sunlight in the house so it is absorbed by the "surrounding thermal mass," a type of "heat battery that stores the warmth." The heat will then go back into the room after sun down.  In the northern hemisphere, buildings should be oriented to the south to maximize solar exposure.  In the southern hemisphere, the opposite is true. 

Some examples of environmentally-friendly homes

 The September issue of Ode magazine featured an American couple who retrofitted a 75-year old, 1400 square foot home. The house is powered by six 200-volt solar panels on the roof, which create 1.2 kilowatts of power. In order to survive on that amount of electricity, they cut back on their energy use. As the couple put it, "We cut about 95 percent of our ­non-renewable energy use."

British Simon Dale built his own house in Wales for £3000. The house is "dug into the hillside for low visual impact and shelter." The retaining walls and foundation were made of stone and mud from the site, and the frame from spare wood in the area (woodlands). The house is powered by solar panels. Like the American couple, Dale and his family use a compost toilet. Roof water is collected in a pond and used in the garden.

Prefabricated houses also fit the definition for environmentally-friendly houses. Prefab houses are built in a factory and then later put together on site. Being built in a factory reduces the transportation impact and can also reduce material usage and off-cuts. Waste from one building can be collected and used for another.

Prefab houses are surprisingly durable. Stalwart Built Homes in Florida builds LEED-certified modular homes that can withstand 200-mile-per-house (320 km/h) winds. "Building in the factory gives us more control of the product," said company president Julius Poston.

No matter what type of building is selected, there are significant environmental achievements as well as financial savings that can be made by pursuing green building.  The building industry in general has evolved, and as studies have discovered, the cost difference between standard construction methods and green buildings is negligible, making it that much easier to do the right thing. 

Related Reading:
Eco Neighborhoods: Where Community Meets Sustainability
Architecture 2030: Combating Global Warming