Unlike the "invisible" energy savings elsewhere in your new home, you'll probably notice the energy efficiency of your new windows and doors.
But keep in mind that any opening in the exterior of your home can increase your heating and cooling costs by as much as 15 percent, so it's important to choose wisely.
Size and quantity
As a general rule, the bigger the pane of glass, the less energy efficient. And the more windows you have, the greater the heat loss and gain.
If you have your heart set on a large picture window or a window wall, invest in the most energy-efficient models you can afford.
Style and materials
The window style you choose can also affect energy loss. Casement windows, which open with a crank or lever, are usually the most efficient, because they seal tighter against the window frame.
Window materials can include wood, vinyl, fiberglass or aluminum. Aluminum windows generally aren't recommended for colder Midwest climates. The other materials all offer approximately the same energy efficiency, but wood requires more maintenance.
The direction your windows face will play a big part in your comfort as the seasons change. Southern windows help keep your home warm during the winter, but if not properly shaded, they could turn the room into a sauna during the summer.
Likewise, a large bank of windows could make a north-facing room unbearably chilly during cold weather. Energy-efficient landscaping can help circumvent these problems.
Your builder can help you maximize the energy impact of your windows, including other conservation techniques like daylighting.
It's also important to make sure windows are installed properly. If a window isn't level or plumb, it won't seal tightly, allowing air to leak in.
Before the finishing trim is hung, check all the windows in your home with a carpenter's level and ask the builder to correct any that might be off-kilter.
After the windows are hung, the installers should add insulation in the larger gaps and caulk the edges of the frame and casing.
A traditional wooden exterior door has an R-value of about four, leaving a big gap in the energy efficiency of your R-19 or R-24 walls. You can prevent this heat loss by opting for an insulated steel or fiberglass door. Both these types provide an R-15 insulating value, and can be painted or stained to resemble wood.
As with windows, it's important that exterior doors are properly installed. Make sure the doors are level and plumb before the trim is added, and check for proper weatherstripping.
After the door and trim are hung, the carpenters should add insulation to the larger gaps and caulk the edges of the casing, on both the interior and exterior sides.