The cost of a home energy audit in Washington depends mainly on a few factors like how intensive you want the test to be. You may opt for a basic or traditional testing, or you can get a more advanced one that uses special equipment pieces and tools. Nevertheless, the goal is to help you save on the cost of your energy consumption. Depending on the process that will be used by the energy auditor, a Washington home energy audit can take about 2 to 4 hours to be completed. Keep in mind that the more intensive and in-depth the testing is, the more time it takes. This means that the cost can be higher. There is really no way to know the exact cost of an energy audit service. That is why most professionals can only give cost estimates that can change at the end of the inspection. On average, most homeowners spend around $290 up to $500 for a home energy audit in Washington depending on the size of the house and the tests that will be made. It has been noted though that older and larger homes are more expensive because of the many inspections that need to be conducted.