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What Makes a Door Energy Efficient?

What Makes a Door Energy Efficient?Exterior doors lead a double life. When they’re open, they provide access to your home or backyard. When they’re closed, they provide a formidable barrier against would-be intruders and the elements. If you’re in the market for a new door, it’s fairly easy to see if it meets your standards for security. The locking hardware is right there for you to inspect. But how do you know if the door you’re considering is up to snuff when it comes to its thermal performance? It’s not quite so obvious. If you’re wondering what makes a door energy efficient, here are a few things to keep in mind before you purchase a new one.

Frame Material

When it comes to door frame materials, you want to choose something that is a poor conductor of heat. Fiberglass front doors and vinyl patio doors are two of the best options in terms of energy efficiency. Both of these materials resist thermal conduction quite effectively. Since steel is good at transferring heat, this frame material is a notch below the others. But most modern steel doors have insulation-filled inner chambers to boost their energy efficiency. Wood doors are the least energy efficient.


Doors come in a variety of styles, from sleek and minimalistic to elaborate and eye-catching, but the single biggest determining factor for energy efficiency is the amount of glass that’s featured in its design. Doors with larger window panels tend to be less energy efficient than windowless doors, especially if the glass is a single pane (see below). With their large windows, patio doors are less energy efficient than entry doors, but modern designs incorporate several features to minimize heat transfer, including insulation filled frames. Hinged patio doors are less energy efficient than sliding models.

Glass Type

Just like windows, the glass in exterior doors is available in standard and high-performance packages. To maximize thermal performance, the glass must have two or three panes. The most energy efficient door glass also has argon or krypton gas between the panes to further reduce heat flow. Premium patio doors are available with these options as well, but to make them as energy efficient as possible, window treatments such as curtains or blinds are a must. They may block your view, but they’ll also block solar heat, which will keep your home cooler during warmer months.

Internal Insulation

The core of a door is either solid or a honeycomb of inner chambers. While solid-core doors are touted for their security, they are not as energy efficient as doors with insulation filled core. Polyurethane foam is most often used to create a thermal barrier that prevents heat transfer. Obviously, the more insulation the better the performance, which is another reason why doors with a small amount of glass or no glass at all are more energy efficient. Insulation-filled cores are smaller in window-dominated models. And as mentioned above, patio door frames can also be augmented with insulation.


The most energy-efficient doors will not provide the thermal performance they’re rated for if they’re not properly installed. Even doors that open easily and seem plumb, level, and square can be misaligned just enough to create gaps for air to get through. It may seem counter-intuitive, but improper installation is more common on pre-hung doors, which are packaged with their frames. That’s because the frames must be properly sealed and caulked to prevent airflow, and if this isn’t done with precision, it could allow air and moisture to seep into your home. Another common problem is weatherstripping that’s damaged during installation.

The Company to Turn to for Energy Efficient Doors

If the time has come to replace your exterior doors, the company to turn to is The Window Depot. We offer homeowners throughout the Tampa Bay area a wide variety of premium products made by industry leaders such as Provia, Therma-Tru, Plastpro, and PGT. In addition to our front and patio doors being energy efficient, they’re also durable, easy to care for, and of course beautiful. Reach out to us today and schedule a no-obligation consultation to learn more. Or if you’d prefer to browse our selections firsthand, drop by our expansive showroom in Palm Harbor. With so many options to choose from, you’re sure to find the perfect exterior door for your home.

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