Current Options In Widow's Energy Efficiency 5
Understanding How Energy Moves Through Windows 5
Tomorrow's Options for More Efficient Windows 8
1. How energy flows through windows: Radiation 6
2. How energy flows through windows: Convection ..............................................6
3. How energy flows through windows: Conduction..............................................7
4. Three Routes to Switchable Windows. 10
Until recently, clear glass was the primary glazing material used in windows. Although
glass is durable and allows a high percentage of sunlight to enter buildings, it has very little
resistance to heat flow. During the past two decades, though, glazing technology has
Research and development into types of glazing have created a new generation of materials
that offer improved window efficiency and performance for consumers. While this new
generation of glazing materials quickly gains acceptance in the marketplace, the research
and development of even more efficient technologies continues.
Gas Fill – A heavier-than-air gas such as argon or krypton is used to fill the space between panes to slow heat transfer.
Glazing – The glass and/or plastic in a window unit that provides visibility yet blocks air leakage and some of the heat flow.
Infrared Radiation – Invisible radiation that humans perceived as heat.
Low-e Coating – Low-emissivity (low-e) coatings on glass surfaces reflect heat energy, but transmit visible light.
Pyrolytic (Hard Coat) Low-e – Durable metal oxides that are fused into the surface of window glass.
Sputtered (Soft Coat) Low-e – A coating on the inside pane of window glass in a sealed unit. It is made of reflective metal deposited in a vacuum.
R-Value – A measure of a window's resistance to heat flow.
Total Solar Transmittance – The total amount of all light spectra that is admitted by t...