Where I work, I see a lot of people leaving their computers on, leaving lights on in their office. Those that work in the factory leave the test equipment and other electronic devices on as well.
Instead of complaining, I decided to make up some bright green post-it notes, and place them on the device, so the person sees the “reminder” when they come back. This way, you don’t need to confront the “accuser” and make them feel bad. Often times, people just forget, or don’t realize that it should be turned off.
Each pad comes with 50 notes, and they can be re-used (like a normal post-it note). Simply scan your work area, or your house, and place the note on anything that should be turned off. Certain items (like refrigerators) need to stay on all the time. Focus on the items that definitely need to be shut off. If you can follow up with this approach and feedback for one month (20-30 days), that should be enough time that behavior starts to change, and people will become more cognizant of what they’re leaving on.