You can use the energy performance ratings of windows, doors, and skylights to tell you their potential for gaining and losing heat, as well as transmitting sunlight into your home. Heat Gain and Loss Windows, doors, skylights can gain and lose heat in the following ways: * Direct conduction through the glass or glazing, frame, [...]
Heat-Absorbing, Tinted Window Glazing or Glass
Heat-absorbing window glazing contains special tints that change the color of the glass. Tinted glass absorbs a large fraction of the incoming solar radiation through a window. This reduces the solar heat gain coefficient, visible transmittance, and glare. Some heat, however, continues to pass through tinted windows by conduction and re-radiation. Therefore, the tint doesn’t [...]
Insulated Window Glazing or Glass
Insulated window glazing refers to windows with two or more panes of glass. They are also called double-glazed, triple-glazed, and—sometimes more generally—storm windows. To insulate the window, the glass panes are spaced apart and hermetically sealed to form a single-glazed unit with an air space between each pane of glass. The glass layers and the [...]
Low-Emissivity Window Glazing or Glass
Low-emissivity (Low-E) coatings on glazing or glass control heat transfer through windows with insulated glazing. Windows manufactured with Low-E coatings typically cost about 10%–15% more than regular windows, but they reduce energy loss by as much as 30%–50%. A Low-E coating is a microscopically thin, virtually invisible, metal or metallic oxide layer deposited directly on [...]
Passive Solar Window Design in Cooling-Dominated Climates
In cooling climates, particularly effective strategies include preferential use of north-facing windows and generously shaded south-facing windows. Windows with low SHGCs are more effective at reducing cooling loads. The following types of glazing help reduce solar heat gain, lowering a window’s SHGC: * Low-E * Tinted * Reflective * Spectrally Selective. Most of these glazing [...]
Passive Solar Window Design in Heating-Dominated Climates
In heating-dominated climates, major glazing areas should generally face south to collect solar heat during the winter when the sun is low in the sky. In the summer, when the sun is high overhead, overhangs or other shading devices (e.g., awnings) prevent excessive heat gain. To be effective, south-facing windows usually must have a solar [...]
Passive Solar Window Design
Windows are an important element in passive solar home designs, which can reduce heating, cooling, and lighting needs in a house. Passive solar design strategies vary by building location and regional climate. The basic techniques involving windows remain the same—select, orient, and size glass to control solar heat gain along with different glazings usually selected [...]
Five Elements of Passive Solar Home Design
The following five elements constitute a complete passive solar home design. Each performs a separate function, but all five must work together for the design to be successful. Aperture (Collector) The large glass (window) area through which sunlight enters the building. Typically, the aperture(s) should face within 30 degrees of true south and should not [...]
How a Passive Solar Home Design Works
To understand how a passive solar home design works, you need to understand how heat moves and how it can be stored. As a fundamental law, heat moves from warmer materials to cooler ones until there is no longer a temperature difference between the two. To distribute heat throughout the living space, a passive solar [...]