Heat-absorbing glass windows selectively reduce the transmittance of visible light relative to solar energy. Using this glass in replacement windows may result in energy savings. Some of the absorbed heat can pass through the window through re-radiation and conduction.
Heat Absorbing Glass
Heat absorbing glass is a glazing unit which contains chemicals that react to heat. This reaction causes the energy to be absorbed rather than transmitted through the glass or deflected by the glass. Heat absorbing glass replacement windows generally have a bronze, gray, or bluish tint and can reduce brightness and glare which allows them to absorb the heat that would otherwise transfer through the window.
The most common colors for heat absorbing glass replacement windows include bronze, gray and green or blue-green. These tints all block solar heat gain in more or less the same proportion but don't alter the perceived color of the view significantly. The colors of the tinted glass generally can blend in well with the home's other architectural colors.
Black tint is counter-indicated for cooling load reduction of heat absorbing glass windows since black absorbs a large percentage of visible energy but doesn't absorb as much heat energy.
Heat absorbing glass windows offer energy efficiency, safety and security, ultraviolet protection, no mirror appearance, privacy and design versatility.
Heat absorbing glass windows deflect solar heat while, at the same time, providing optimal visible light transmission. This facilitates lower energy costs for lighting and heating. Heat-absorbing glass windows provide a higher level of effective sun control when used as the outer layer of a double-pane window.
Safety and Security
The glass solar interlayers of heat absorbing glass windows combine to absorb the force of an impact. If the impact breaks the glass the glass fragments remain adhered to the solar interlayer and do not shatter or splinter.
The solar interlayer of heat absorbing glass replacement windows allows needed light to transmit through the glass panels while blocking up to 99% of the sun's UV rays.
Architectural laminated glass can be used in a variety of applications including replacement windows, curtain walls, doors and skylights.
Tints of heat absorbing glass windows change the window's color and increase visual privacy. These tinted glass panes retain their transparency from the inside while reducing the brightness of the outward view.
Heat-absorbing glass reflects a small percentage of visible light. It does not present a mirror-like appearance which is common with reflective glass.
Homeowners who purchase heat absorbing windows should review the disadvantages of the glazing, as well as recommendations to create better heat absorbing glazing options, before making the purchase.
Heat which is absorbed by the glazing of a heat absorbing glass panel may transfer to the structure. This causes only a small reduction in overall solar heat gain compared to other types of replacement window glass. In addition, people sitting near a heat absorbing glass window may feel uncomfortable due to the heat radiation. The inner layer of the glazing reduces this transfer somewhat.
Some tinted glazings, including bronze and gray colors, may force a trade-off between visible light and solar gain. There is a greater reduction in visible transmittance than in solar heat gain coefficient. This may decrease the glare by reducing the evident brightness of the glass surface. However, it also diminishes the amount of daylight entering the room.
Homeowners who are more concerned with their home's daylighting may wish to purchase a high-performance coating or tint as an additional means of controlling glare. Tinted glass can provide enhanced visual privacy during the day by reducing visibility from the outdoors. At night, however, the effect is reversed, making it more difficult to see outdoors from the inside, particularly if a reflective coating is combined with the tint.
Homeowners who want to enjoy the benefits of heat absorbing glass windows but wish to address the problem of how to reduce daylighting issues can purchase a window with a high-performance tinted glass -- spectrally selective glass windows. These windows transmit the daylight portion of the solar spectrum but continue to absorb the near-infrared portion of the sunlight. Using special additives which are included during the float glass process, window manufacturers create the spectrally selective window glazing which is durable and can be used in both single- and multiple-glazed window applications.