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A Guide to Energy-Efficient Windows and Doors

Section 3 — Understanding Basic Terms

3.1 Window and Door Types

Figure 4There are two types of windows: those that open and those that don't—called operable and fixed, respectively (Fig. 4). In high wind areas, use as many fixed windows as codes allow, keeping in mind that floors with bedrooms need at least one operable window or exterior door for emergency exit. Fixed windows are more efficient because of their better airtightness characteristics. They also offer the most safety and security.Figure 5

Of the operable units, there are many forms: awning, casement, hopper, horizontal slider, vertical slider (either single- or double-hung) and turn-and-tilt (Fig. 5).

Figure 6


There are two ways of sealing operable windows to minimize air leakage: with a compression or a sliding seal. Windows with compression seals are generally the more airtight of operable types and should be the window of choice whenever possible. Casement, awning, hopper and turn-and-tilt windows, for example, should have a closure/locking mechanism that pulls the unit tight against the seal (Fig. 6). Make sure the gasket is a compression, neoprene rubber type.Figure 7

Doors are a little less complicated. They are either: solid, solid with an insulated core, solid with window(s), or solid with an insulated core and window(s). Patio doors operate like a large horizontal sliding window. Hinged French doors, with a solid center post to close against, or rolling doors with a compression-fit like an aircraft door, are more energy-efficient (Fig. 7).Figure 8

Some materials reduce heat flow better than others. Solid wood doors, for example, are not as good as metal-clad, insulated core doors, depending on the style of doorFigure 9 and insulation material used to fill it (Fig. 8).

Otherwise, doors have a frame, sill, optional glazing, and rough frame opening in a wall as do windows (Fig. 9). Like windows, some doors are even installed in the frame and sill system while still at the factory.

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