Sustainability is expressed as meeting present environmental, social, and economic needs without compromising these factors for future generations A practice cannot be said to be 'sustainable for X years/generations.' The use of any span of time disqualifies the activity. Sustainability is for perpetuity.
Sustainability also means greater efficiency in resource use, ultimately giving benefits to economic growth and overcoming poverty, as well as health and quality of life.
Sustainable design and sustainable development are critical factors to sustainable living. Sustainable design encompasses the development of appropriate technology, which is a staple of sustainable living practices. Sustainable development in turn is the use of these technologies in infrastructure. Sustainable architecture (see Green building) and agriculture are the most common examples of this practice.
What is it? The Hexayurt
is a refugee shelter system based on work done at the Rocky Mountain Institute. It uses an approach based on "autonomous building" to provide not just a shelter, but a comprehensive family support unit which includes drinking water purification, composting toilets, fuel-efficient stoves and solar electric lighting. Other systems can be added in a modular fashion.
Is this for real? Yes. Both the American Red Cross and the US Department of Defense have examined the Hexayurt system in detail and found that it has considerable merit and utility. I hope that we will see it in use by international agencies within two years.
The best place to get started is to read the slides from the presentation Vinay Gupta gave at the Pentagon in December 2006: Pentagon Presentation (pdf) - 20 pages, not much text, and the best summary of the system we currently have online.
Creating a solar cooker out of local invasive species and waste materials in order to pasteurize water and be an alternative to the use of fossil fuels for cooking food.