To achieve the absolute best efficiency you need to seal your home as tightly as possible.

• Eliminate the leaks around windows and along the foundation
  
• Insulate and manage moisture penetration
• Recirculate the inside air
• Manage the moisture
• Filter out the contaminants like dust, allergans, smoke, CO and even CO²
  
• Provide makeup air to replace any vented by devices such as range hoods or dryers
• Use efficient lighting and appliances like TV's and computers
• Watch those parasitic loads when devices are turned off. 
• Provide air locks at entrances (don't laugh, a properly situated "mud room" is an air lock that keeps heat in while allowing people to go in and out. An entry foyer can be the same.)

There are all sorts of problems that are new to an energy efficient home. This is what engineering is all about. Ultimately roof surfaces can collect solar energy you might collect enough to provide hot water for your home.