Am I stupid or what...

Right when I opened the door of my room, I felt the cool and refreshing air coming out.
Hey! I don't have any roommates!
Oh, don't tell me I made a real dumb mistake!
No...

yes... the indicator lamp showing that the energy eating machine was in operation was glowing strongly... that means I left it on for more than 12 hours...

Burying my head in my hands, I had to admit I made one of the most basic mistakes when living alone...
So much for my way of helping out in stopping the global warming!