For the purpose of simplyfying future discussions, I would like to share my definitions of energy efficiency and energy conservation. First, energy efficiency consists of the measures currently installed or that can be installed in a property to retain thermal mass at the lowest rate of consumtion. It includes the framing, insulation, lighting, air seal/barrier and mechanical systems, among others. Energy conservation refers to our behavior toward energy consumption. It is the lowest cost but sometimes the hardest to change. Obvious examples include frequent changes in the temperature settings on thermostats, leaving lights on when unnecessary, etc.

When combined and utilized with each other, savings can be significant.