NRFC labels help you evaluate the energy performance of new windows and allow you to comparison shop for the most efficient options. Use them when you make your choice of windows.

But whether you are replacing a window or installing one in a newly constructed building, there are considerations other than just efficiency to keep in mind.

Different combinations of frame style, frame material, and glazing will yield very different results when comparing energy efficiency and cost. A fixed-pane window is the most airtight and the least expensive, for example -- it would be the best choice if you wanted to add sunlight to a room without increasing ventilation. A window with a wood frame will usually conduct less heat than one with an aluminum frame. If you're seeking efficiency, a double-pane, low-e window would be just as efficient as a triple-pane untreated window, but it would cost and weigh less. Consider the benefits carefully.

No one window is suitable for every application. Many windows are available that serve different purposes, and you may discover that you need different types, depending on the directions that your windows face and your local climate. To make wise purchases, first examine your heating and cooling needs and weigh the following considerations.

Think About the Window's Appearance.

• Choose the right size and shape.
• Pick a style that matches your home's design.
• Match the materials used in the frame.
• Consider the color and clarity of the glass.

Think of the Functions You Want this Window to Perform.

In the location it will be installed, what should this window do?

• Light the room with daylight?
• Control glare?
• Reduce fading of furniture and drapes?
• Insulate and aid in thermal comfort?
• Prevent condensation?
• Improve ventilation?
• Dampen sound?

Think About the Costs of a Window in this Particular Location.

Consider more than just the initial price of a window. These factors are also important.

• What's the cost of installation?
• What's the cost of maintenance, over time?
• What sort of warranty does it have?
• How long will this window last before you need to replace it?
• Will you need to buy any extra interior and exterior window treatments, like awnings and blinds?
• How will this window affect your heating and cooling costs over time?
• How will this window impact the resale value of your house?