Are there any smart home technologies that will save me money?

I have received many thoughtful responses during the past two weeks on the advantages and disadvantages of heat exchangers and solar panels.  As you may be able to tell, I'm interested in both climate control as well as saving money (I have twins to send to college soon!) Thank you very much for all your thoughtful insights and discussions. 
  • Are there any smart home technologies that will also save me money?
  • Will smart thermostats save me money?
  • Will smart blinds pay for the extra cost?
  • Will smart lighting pay for itself?
  • Are battery powered tools more efficient than plug-ins?