10-25-2011 01:18 PM
This depends on several factors.. age of home and appliances, construction materials used, etc. My gas/electric runs about ~275 during the summer months and ~75 during winter months I have dual a/c units for a 2600 sq ft house. So you should assume lower monthly if all things held similar except size of the house. Hope this helps?
10-25-2011 04:54 PM
Yes those generally have only one unit. If energy cost is a concern make sure you go newer homes (as you stated you are) and the direction that the house faces can and will play a role in your overall heating/cooling bill and your total energy budget.