Air Conditioning Window Units

How much energy does central air conditioning instead of window units?
Do you have central A / C really sure that most energy window units? If so, how much in energy costs per year for a normal sized house?
How funny. For some reason (for being our central A / C uses $ 400. U.S. A MONTH in Texas, sometime up to $ 600) I would definitely think that the unit window used less. That's in the summer months. In the winter runs us about $ 200. And this is a new home, about 7 years old! It seems like the most old households consume less energy than that! Argh! This is definitely a good question and interesting! (I hope you do not live in Texas, LOL)
Tips On Air Conditioning Troubleshooting For Window Units