We recently updated the EERE style guide to explain when to use "U.S. Department of Energy" and "Energy Department" in your EERE products.
"U.S. Department of Energy" is the preferred way to refer to the Department, and this term can be used on all EERE products. However, "Energy Department" may be used in press releases and other transient communications, such as news or events. You can read the full entry on the EERE style guide.
And, as always, if you have any questions you can ask in the blog comments or send an email to the Communication Standards webmaster.
