Monday, October 27, 2008
Vanquish 'energy vampires'
By Ann Robinson and Annie Vernon
We're afraid it isn't going to be cheap heating our homes this year. With energy costs expected to soar this winter, it is more important than ever to do our part to make our homes as energy efficient as possible.
That means controlling "the energy vampires" that slowly suck the energy and heat out of your home.
The first culprit is your front door. If you have older exterior doors, air and heat may be leaking out, driving up the energy bill.
One common type of exterior door has a steel skin with a polyurethane foam insulation core. It usually includes a magnetic strip (similar to a refrigerator door magnetic seal) as weatherstripping. If installed correctly and if the door is not bent, this type of door needs no further weatherstripping.
The R-values of most steel and fiberglass-clad entry doors range from R-5 to R-6 (not including the effects of a window.) For example: A 1 1/2 inch (3.81 cm) thick door without a window offers more than five times the insulating value of a solid wood door of the same size.
Glass or "patio" doors, especially sliding glass doors, lose heat much faster than other types of doors because glass is a very poor insulator. Most modern glass doors with metal frames have a thermal break, which is a plastic insulator between the inner and outer parts of the frame. Models with several layers of glass, low-emissivity coatings, and/or low-conductivity gases between the glass panes are a good investment, especially in extreme climates. Over the long run, the additional cost is paid back many times over in energy savings.
When buying or replacing patio doors, keep in mind that swinging doors offer a much tighter seal than sliding types.
After years of use, the weatherstripping on a sliding door wears down and starts to leak air. You can replace the weatherstripping on some glass door models, but for others, you may need to replace the entire unit.
If you are just replacing or adding weatherstripping to your old doors, you will want to choose a type of weatherstripping that will withstand the friction, weather, temperature changes, and wear and tear associated with its location. For example, when applied to a door bottom or threshold, weatherstripping could drag on carpet or erode as a result of foot traffic. Weatherstripping in a window sash must accommodate the sliding movement of the panes — up and down, sideways or out. The weatherstripping you choose should seal well when the door or window is closed while allowing it to open freely.
Felt and open-cell foam weatherstripping tend to be inexpensive, but they are susceptible to weather and ineffective when it comes to blocking airflow. Vinyl is slightly more expensive than felt and foam, holds up well to traffic and resists moisture. Metal weatherstripping (bronze, copper, stainless steel and aluminum), as you would expect, is the most expensive option but will last for years. Metal weatherstripping also adds a nice touch to older homes where vinyl may seem out of place.
Whether you replace your exterior doors or just seal the drafty old one, you will be on your way to a greener, more comfortable home. Next week we will have more tips on how to be an "energy vampire" slayer. As always, we welcome your home architect design questions at firstname.lastname@example.org.