I'm helping my father in law try and reduce his electricity bill, but I'm a bit lost on his heating options. He's renting a small 2-bedroom unit, and there are two wall-mounted space heaters installed - one in the lounge and one in the hallway, both at floor level. I think they may be night-store heaters, because he has a night rate on his power bill, but I don't know anything about night-store heaters - how they work, are they any good? Do they store heat/energy and release it during the day? If not, what is the point of them? Or could they just be bog-standard electric heaters and the night rate is for something else?