Yes, you can make an older home more energy-efficient, which also can improve its value.  “EEMs can be used for both homes that already exist and homes that are newly built,” says Boris Dorfman, president and fund manager of LBC Capital in Long Beach, California. “However, they are usually linked more often with existing homes. This is because they let homeowners update their houses with energy-saving features, which could help cut down on future utility costs.”