Energy-Efficient Doors
Your doors have to a lot to do, particularly exterior doors. Essentially, they need to prevent things you want to retain from escaping, and keep things that you don’t want out of your home, all while allowing you to come and go as you please. “Things” that might be as small as molecules of hot air, or as large as a burglar. That’s a tall order for a simple rectangle on hinges!
And since any door, particularly a front entry door, is a major design element of a home, it must be aesthetically pleasing as well as functional and efficient.
Doors that are part of a sustainably built house must be especially good at creating a seal between the outside and inside. A large part of energy conservation is about reducing heat (or cold) exchange with the outdoors; windows and doors are the areas of greatest heat loss in almost all houses. Sustainable building practices include the entire life-cycle of each part, so a green home door should ideally be produced in an ecologically sound way and it should be recyclable.
Energy Efficiency
Let’s look at energy-efficiency first. A good exterior door will fit tightly and use the best available weather-stripping technology. The most energy-efficient doors are made of fiberglass or wood-clad steel, or painted steel, filled with a core of polyurethane foam. These doors are typically sealed with a magnetic strip like that on a refrigerator and they need no further weatherstripping if they are well-installed. They are about five times as insulating as a wooden door. To “up” the green factor, look for doors that contain recycled steel.
Your doors represent an invitation into your home—they are part of the fabric of your house that you and your visitors will encounter on a daily basis, so this is an area in need of your green attention.
You can also buy both interior and exterior fiberboard doors molded from up to 100% recycled wood fibers. These products have greater insulating values than wood and are a good use of lumber mill waste products. Some new wooden doors are also made from recycled lumber, often of woods no longer readily available.
Avoid purchasing doors made with tropical wood veneers like luan and mahogany, which are often harvested in a non-sustainable manner. Domestic wood veneers such as cherry and oak provide a more sustainably sound choice.
Windows
Windows contained in doors are less energy-efficient than solid options, whether they are french doors, patio doors, or doors containing simply a small peek-through window. Newer doors with glass use the same technologies as in energy-efficient windows, such as:
- solar-control (low-emissivity) coatings
- double panes with inert gas fill
- tinted glass
If you are shopping for a new door, look for those rated highly by Energy Star , or the NFRC (National Fenestration Rating Council), both of which provide energy-efficiency labeling on doors and windows.
What if you adhered to the sound ecological maxim that the best form of recycling is reuse and found some beautiful old doors you want to install? Or perhaps you like the doors on your house just fine, apart from how drafty they are? In these cases, or if your new door has a great deal of glass in it, you will want to both weatherstrip your door carefully, and possibly install a storm door to create a second insulating barrier.
Weatherstripping
Weatherstripping is the application of a strip of some combination of materials around your door perimeter to improve the air seal. Almost all the heat energy loss associated with doors is not through the surface itself, but through the cracks between the door and the wall, and between the door casing and the wall. In terms of energy conservation, good weatherstripping and caulking are more important than the actual materials that comprise your door.
It’s recommended that you have an energy audit performed to help you discover all of the air leaks in your house before you start retrofitting. In the meantime, here’s a simple pre-test: Try passing a piece of paper between your closed door and the wall or floor—if you can, you’ve got a big air leak. The Department of Energy has an excellent consumer’s guide about the pros and cons of various weatherstripping options.
Finishing Your Doors. Don’t compromise the quality of your energy-efficient, recycled-materials door by painting it with toxic enamel or varnish! Choose an environmentally friendly finish with a low- or zero-VOC (volatile organic compounds) emission rating. Some good manufacturers to check out include: Bioshield, AFM Safecoat, and the Benjamin Moore Pristine and EcoSpec lines.
Area-Specific Doors
Storm doors are a good way to increase the energy efficiency of an existing or recycled door, but you won’t get much more efficiency out of a new, insulated door by adding a storm door. Look for low-e glazing and insulated metal frames. Some have removable glass and double as screen doors in summer. Don’t install a storm door over a door that gets much direct sunlight, as you will be creating a heat trap between them that can damage your door.
Interior doors don’t have the burden of needing to be fully sealed and insulated the way exterior doors do, so this is a good use for recycled doors. Or, buy a wooden door certified by the Forest Stewardship Council as a product that is sustainably harvested from a managed forest.
What about garage doors? Although they may not need to be insulated if your garage is an unconditioned space, look for garage door companies that use recycled steel and aluminum.
Patio doors are difficult to insulate and there are not many storm door options for them. Consider replacing them with a combination of insulated exterior doors and double-paned glass windows. If you want to keep your patio doors, apply an after-market low-emissivity coating to the glass or put up a solar shade in order to keep the sun’s heat out. Also install insulating blinds or shades for winter.
Your doors represent an invitation into your home—they are part of the fabric of your house that you and your visitors will encounter on a daily basis, so this is an area in need of your green attention.
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