Anyone believing the real-estate hype these days is hearing that the market is turning around. Never mind the real indicators we'll skip that discussion for the moment.
Energy Star homes are built to have a more efficient "envelope" to help keep the house comfortable while using less energy. It is a part of the same program that rates appliances, computers etc. The process of getting a home qualified is pretty straight forward. Build to a standard, use the right materials and get the house inspected. The EPA has a nice description of the process and differences.
The problem is that just because a builder has a design that meets the specs doesn't mean it will really be very efficient. Sure if the standards are followed the envelope will be good. However, it doesn't mean the design is good. Take for example the house we're in now. To be clear it doesn't seem that this house actually was qualified with an inspection rather it's a design built to the standard. Read more about Homebuyers should be wary of Energy Star claims