What is the definition of a "green building"?

IMHO, commercial buildings and homes should be viewed quite differently in terms of what "green" means. The concept of "green" has a separate hierarchy of needs, whether one is contemplating a commercial (income producing) property or a single family, owner occupied home. Let's focus on the "quality of life" aspect mentioned, because if that isn't met, nothing else matters. To be clear, I'm talking about owner-occupied homes here, not income producing properties, commercial green buildings, etc.

Assuming that "green" and sustainable are synonymous, for a home to be sustainable, it has to support, not endanger, the people who live there. At its most basic level, a home provides shelter and a place to store food. However, unlike an income producing property (eg. commercial green building), most people do not realize that your home is a liability, not an asset. Your home is a source of expenses, not income. Unless you work from home, are incorporated, and have a home office with a productive business that turns a profit, your home takes money out of your pocket every month. Like clockwork.

In my view the personal sustainability hierarchy starts with making sure that the home puts as little pressure as possible on its owners from an economic standpoint so as to improve the quality of life of those who live there.

Maslow's hierarchy of needs sums it up nicely... if you're choking and desperately gasping for air, the last thing you're thinking about is whether you will complete your masters thesis on the origin of consciousness. The same can be said about paying your mortgage. If you are deep under water every month because you have too much home, or if you've lost your job, or both, all you will think about is the shortest term solution to resolving the pain. (eg. I've got to get a job, or I've got to sell this house!) Neither of those are long term, "sustainable" solutions. As the flight attendants tell us before every flight, put your own mask on first, then put on your child's mask. Whether a building is "green" environmentally (i.e. what happens to the Earth) is trivia if the people who live there can't afford to stay.

The fact is that we need a place to live, so why not make that place as sustainable as possible. Sustainable meaning congruent with, and supportive of the process of realizing our own lives so that we can be as productive as possible and do our work.

Applying green building concepts is one way to make your home more productive. To shift the balance away from the liability side, and more towards that of an asset. To help its inhabitants achieve self-actualization.

If you are considering buying a home, first, think small. If you already own a home and have extra cash that you are thinking about investing for your future, look at the investments that you can make in your home's efficiency that can make stock market returns look paltry over time. A reduction in energy expenses is the same as a raise. An excellent report titled "Unlocking American Efficiency" sponsored by United Technologies and published by Rhodium Group outlines some examples of returns on energy efficiency in homes, businesses and government. Using current energy price forecasts from the U.S. Department of Energy, the report outlines the returns on energy efficiency investments and compares them to cash, corporate bonds, government bonds, equities (stocks), venture capital and estimates that the highest-performing energy efficiency investments would pay for themselves within 4 years (a greater than 25% return).

Buy small. Live small. Figure life out on your own terms. Minimize the external pressure on yourself so that you can create and live the life you want.