Misao Seki/関操

It's Winter. Misao's "friends"(fake friends but they don't realize that they are fake friends) "accidentally" left them at a old creepy mansion and since it's freezing cold outside they decide to go inside hoping it'll be even a tiny bit warmer. It's freezing out here They're shivering. When they go inside it's pitch dark but the light of a turned on heater lights up a room a tiny bit but this house is old and abandoned so how is there electricity for that heater?