In urban areas, the sustainable designs of what is sometimes called the "new urbanism" are becoming popular. They take advantage of making high-density living enjoyable and efficient.
Multi-Use Green Designs
One of the tenets of the new urbanism is combining residential and retail spaces in the same building. This allows city dwellers to easily walk to the bakery and cleaners around the block rather than making trips all over town. It also seeks to eliminate the need for automobiles by placing such buildings near public transit such as urban train lines.
Green Certification
There are organizations that make inspections and give out ratings of green certification. Not unlike the organizations that certify organic foods in the US, these organizations are NGOs that have drafted documents that outline the basic requirements of sustainable building and design practices and judge buildings accordingly.
Water-Saving Green Designs
Conserving water in these designs is a high priority. Many of the most highly rated green buildings make the best possible use of water, often even harvesting it from the sky for use. Eco-roofs are one way that gray water from residential and business use can be recycled for irrigation. Moreover that irrigation can support plants that help cool in the summer and function as insulation in the winter.
By building such developments with water conserving devices such as low flow toilets and facets, high capacity washing machines, hot water on demand and others, vast amounts of fresh water can be saved in the first place.
Urban Agriculture
These buildings are, perhaps surprisingly, well-suited for urban agriculture. Green roofs can be used to grow fruiting crops and even trees that are now gracing roofs all over the world. As agricultural and horticultural productions are brought closer to city, more people in urban areas will begin to have a stake in their own food.
Retrofitting Old Designs To Green Designs
Not all building projects are new construction. There are many old buildings that can be retrofitted to adapt to a new, low-carbon urban environment. This process goes well beyond installing some insulation. The actual function of many older buildings can be adjusted with redesign to encourage new urbanism in older buildings.