CELLPHONE CHARGERS COFFEE MAKERS VIDEO GAME CONSOLES kids, lord voldemort has hidden ENERGY VAMPIRES all over HOGWARTS. they are all over your home too. energy VAMPIRES vampires are devices that suck energy from your home even when they are turned off. below are some of the most common energy vampires lurking in your home. even MUGGLES can help! you can be an ENERGY VAMPIRE SLAYER by unplugging these devices when not in use. COMPUTER MONITORS CAMERAS beary potter needs our help! help him find the snitch that uses the least amount of energy PRINTERS ANSWER: In this list, cameras use the least amount of energy, coming in at an average of 3 watts. Worst enregy vampire on the list? Computer monitors which range from 20 to 100 watts depending upon monitor size and model.