An energy mortgage is a mortgage that credits a home's energy efficiency in the home loan. For homes in which the energy efficiency can be improved, this mortgage allows the money saved in monthly utility bills to finance energy improvements.
For an energy efficient home, it could mean giving the home buyer the ability to buy a higher quality home because of the lower monthly utility costs of heating and cooling the home.
Energy Improvement Mortgage - Finances the energy upgrades of an existing home in the mortgage loan using monthly energy savings
Energy Efficient Mortgage - Uses the energy savings from a new energy efficient home to increase the home buying power of consumers and capitalizes the energy savings in the appraisal
*Above chart provided by: http://www.pueblo.gsa.gov/cic_text/housing/energy_mort/energy-mortgage.htm