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annealed glass- Ordinary window glass which can easily break or be cut to size.

argon - a nontoxic gas that is heavier than air, therefore it reduces the transfer of heat and cold. It also reduces noise.

tempered glass - Five times stronger than annealed glass. It can also "flex" or bend significantly more without breaking and it resists impact, shock, thermal and mechanical stress. If it breaks, it fragments into small harmless rounded pellets. Tempered glass is created by heating annealed glass to near its melting point, rapidly cooling its surface and allowing the inner core to cool naturally. The glass must be cut to size before the tempering process.

laminated glass - Consists of two layers of annealed glass with a vinyl interlayer bonded to the glass. The interlayer prevents the glass from falling out should it break. Because laminated glass is made up of two sections of annealed glass (laminated cannot easily be made with tempered glass), it is much more susceptible to stress cracks and thermal or mechanical breakage than tempered glass.

thermal stress - A result of extreme temperatures, thermal stress can cause ordinary annealed or laminated annealed glass to break.

mechanical stress - A result of snow load, impact with an object, deflection of the supporting greenhouse structure etc., mechanical stress can cause ordinary annealed or laminated annealed glass to break.

insulated glass - Hermetically sealed factory insulated glass used by Everlite is one full inch in overall thickness consisting of two 1/8" pieces of glass separated by a 3/4" aluminum spacer. The bronze aluminum spacer is filled with a moisture absorbing dessicant to permanently keep out dirt, moisture and, condensation while providing an insulating dead air space which significantly reduces heating and air conditioning costs.

bronze tinted glass - A bronze coloring within the glass itself that reduces glare.

low-e (Low-emittance) - It is the industry term for glass having a special chemical coating which reflects certain wavelengths of the light spectrum. The coating results in a glass which has a particularly low emissivity. It's virtually colorless and increases the R-factor (resistance to heat gain or loss).

reflective heat gain - (BTU/Hr./Sq. ft.) The total solar heat gain through glass for a specific set of conditions. The higher the relative heat gain the more solar collection for winter heating.

shading coefficient - The ratio of solar gain through a particular glazing system to solar heat-gain through a single lite of clear 1/8" thick glass under the same conditions. The lower the shading coefficient, the lower the solar heat gain.

"R" value/factor - The overall coefficient of thermal resistance (air to air) in Hours/Sq. ft/Degrees F/BTU. The higher the "R" value the more insulated the system. ("R" = 1/"U").

"U" value - The overall coefficient of heat transmission in BTU/Hours/Sq. ft./Degrees F. The lower the "U" value the more insulated the system.