WINDOWS

Reducing heat loss or gain in homes often includes either improving existing windows or replacing them. Low-cost options available for improvement are caulking, weatherstripping, retrofit window films, and window treatments. Replacing windows will involve the purchase of new materials, which should adhere to certain energy efficiency standards.

Different combinations of frame style, frame material, and glazing can yield very different results when weighing energy efficiency and cost. For example, a fixed-pane window is the most air-tight and the least expensive; a window with a wood frame is likely to have less conductive heat loss than one with an aluminum frame; double-pane, low-e window units and triple-pane windows have the best energy efficiency. 

No one window is suitable for every application. Many types of windows and window films are available that serve different purposes. Moreover, you may discover that you need two types of windows for your home because of the directions that your windows face and your local climate. To make wise purchases, first examine your heating and cooling needs and prioritize desired features such as daylighting, solar heating, shading, ventilation, and aesthetic value.

DOORS

If you decide to replace your door, modern insulated metal or fiberglass doors are a better investment than wooden doors. Even though they may cost more, they are much more durable and insulate better than wooden ones. They have the added advantage of offering more of a deterrent to possible intruders.

When replacing patio doors, keep in mind that French or swinging doors offer a much tighter seal, and are generally more energy efficient than sliding doors. To reduce the possibility of condensation problems, all glass doors should have a "thermal break": an insulator between the layers of glass and the inner and outer parts of the door frame. Doors manufactured with several layers of glazing, low-e coatings, and argon gas between the glass panes are a better investment than plain double glass. Over the long run, the additional cost is paid back many times over in energy savings.