Duct Testing is a new requirement in the California Energy Code. Whenever a furnace needs to be replaced, the duct system must be checked for air leaks, and then sealed to achieve a certainly allowable level of leakage. This improves system efficiency and saves energy for everyone. Heating and cooling is one of the biggest areas of energy use in our state. A duct test must be performed by someone other than the contractor performing the installation and the results are reported to the State of California. The paperwork process is similar to a smog test.