Is this $500/month year round or is this just in the summer?
I would suspect the AC is a big utility draw. I almost never run ac, because I get an ocean breeze. When i do run it, my utility goes up *significantly*.
Do you use your oven a lot? Is your fridge always running (if so, why aren’t you chasing after it…hark hark hark. sorry, couldn’t resist). If your fridge is always running, it means you are probably either setting the temp too low OR are packing the fridge so tight that it’s no longer efficient).
Electric. Even if appliances are plugged in, most of them still draw some power, especially all the AC adapters and transformers. However, I’m not sure that would be really that much of a draw. Unless you have some high powered amp that you leave on. Monitors are big draws.
My gas bill is pretty bad in the winter. I have a gas stove top, gas dryer, gas oven, gas water heater.