I am hoping to be able to build a house within the next couple of years. I am on a limited budget but am also interested in energy savings. I know solar is out of range but I am thinking about a small passive solar house. I am in a cold climate and am building a house for 2 adults and a baby. What energy saving features are worth it costwise? How small is too small? Any other advice? Also in my climate I need a basement. Thanks for any help.