An Ecohouse Is:

An ecohouse is built in such a way that reduses energy consumption and waste. An eco house reduces the buildings negative impact on human health and the environment, through better design, construction, siting, operation and maintenance. An eco house is a combination of sustainable design, sustainable development and sustainable living.
Eco houses are designed and built as part of the larger ecology of the planet; the design and construction of the building are done in harmony with the natural environment. Studies have shown that buildings are the most damaging polluters on the planet, consuming over half of all the energy used in developed countries and producing over half of all the climate-changing greenhouse gases.

A successful eco house should give the owner the ‘best of both’ by providing less of an impact on the environment along with a healthier place to live and lower ongoing running costs.
As building technique has become more sophisticated during the 20th Century, architects have taken up the challenge by generating more complex forms. Highly abstract and complex theories have manifested themselves within overtly labyrinthine geometry. As form has become progressively mannerist, the eternal and timeless quality of architecture has been reduced to disposable and consumeristic whim.


Here are the links that I have got the information from:
Ecobob
appfa
marquetteturner

What Is Sustainability?

Well, you should know that sustainability is a word, (unless you're an eejit) but what does it mean? I can tell you this: Sustainability is a noun, and means being able to:

1.	to support, hold, or bear up from below; bear the weight of, as a structure.

2.	to bear (a burden, charge, etc.).

3.	to undergo, experience, or suffer (injury, loss, etc.); endure without giving way or yielding.

4.	to keep (a person, the mind, the spirits, etc.) from giving way, as under trial or affliction.

5.	to keep up or keep going, as an action or process: to sustain a conversation.

6.	to supply with food, drink, and other necessities of life.

7.	to provide for (an institution or the like) by furnishing means or funds.

8.	to support (a cause or the like) by aid or approval.

9.	to uphold as valid, just, or correct, as a claim or the person making it: The judge sustained the lawyer's objection.

10.	to confirm or corroborate, as a statement: Further investigation sustained my suspicions.

The word sustainability has become increasingly prominent in recent years. It is seen by some as just another hollow buzzword, and is often used interchangeably with concepts such as environmentalism or being ‘green’.

Note: I have got information from:
www.sustain.canterbury.ac.nz/sustainability/whatis_sustain.shtml
http://dictionary.reference.com/dic?q=sustainability&search=search