Smart energy efficient design is achieved with a reasonable blend of several basic building technologies. 

First we insulate well to reduce heat losses, second we use passive solar to aid in winter heating and reduce summer cooling needs, then third we attend to the many "little" items that can add up to make a difference.

As detailed in the section on insulation, energy costs can be cut up to 35% by insulating very well.   So a monthly winter heating bill of $200 would drop to $130.  By adding in passive solar technology the $130 can drop to less than $70.  Earth berming increases the savings further.  So maximum savings is gained through a blend of technology.  Below is a table of where a typical homes uses energy and what we did to reduce the needs.  By doing all of this our total energy costs have been cut over 50% compared to similar families and homes in the area.   

For a solar home one needs to balance orientation with thermal mass and window area.  The general rule of thumb is you want the south facing window area to be about 10% of your floor area.  If you go much above 12% then you can easily suffer from overheating in the day.  Much less than 8% and you will not gain enough heat to make it worth while.