20-Year Prospect
There's great potential for green jobs. As the population grows, everyone is looking for ways to do more (or at least uphold the status quo with less). That's good news for anyone interested in auditing energy. With your expertise, businesses and homes will use less energy and provide a comfortable environment for the foreseeable future.
Can you take a little more good news? Energy auditor jobs are not the kind that can be sent overseas like so many manufacturing and customer service jobs are. Also, robots won't be ruthlessly stealing your jobs with their metal death-pincers. So there's that. This work isn't likely to become obsolete any time soon. At least as long as people are still using energy for things, they could use somebody to tell them how to do it better.