My friends are I are starting a project to replace the vents in our houses. We are using a product called "The Activent." You electronically set the vent to the specified temperature that you want so that when your heater/AC is running the vent shuts off for that particular room when the desired temperature is reached and redirects the rest of the air to the other rooms. This allows your heater/AC to run for a shorter amount of time and thus saving you money! I think this product is a really easy and effective way to save money and go green at the same time!