how do energy efficent homes work?

by Sean Micheal Hanekamp
(Laural Hall school )

I would like to know how energy efficient houses work.Do they have something in the way that the houses run or do they use some type of energy that causes them to be more efficient.Is a green home more ecosystem friendly than a regular home that is not ecosystem friendly.What all goes into the process of making an energy efficient home. What kind of energy source does a ecosystem friendly home run on?

How long does it take to build a ecosystem friendly home and what all materials are used to make a environmental friendly home, when they are being built?