Probably the most important green home upgrade to consider when building a home is proper insulation. Insulation can cost a considerable amount if you wait to install it at a later date, so it's best to take care of it during initial construction. As we've mentioned several times, heating and cooling account for nearly half of your home's energy consumption [source: Archer]. Proper insulation will ensure that expensive energy that's heating and cooling your home isn't escaping out the windows or through the roof. Unfortunately, there isn't anything you can do to completely prevent heat from escaping from your house in the cool months, or entering the home in the warm months, but properly insulating the walls and attics can slow the rate significantly.
While there are many different types of insulation to choose from -- fiberglass, foam and cellulose -- nothing is as important as choosing the right person to do the installation. The best contractors will use an infrared camera once installation is complete to ensure there aren't any gaps or holes where heat is escaping [source: Sachs]. To make your home even more of an insulated fortress, you may also consider upgrading your weather stripping and sealant around the doors and windows.