In our hot southern climate, energy performance is critically important but poorly understood because of the variety of products available, complicated terminology, and rapid technological advances.

U-Value or U-Factor measures the rate of heat transfer through a window from outside to inside or vice versa. A lower value is better and is more important when there is a large temperature difference between outside and inside air temperatures (northern climates).  U-Value is improved with multiple layers of glass, argon filled airspaces, frame materials that reduce heat transmission (wood, vinyl, thermally broken aluminum).

SHGC - Solar Heat Gain Coefficient measures the increase in temperature in a space caused by solar radiation and a lower value is better.  New US Deptartment of Energy Energy Star standards mandate an SHGC of .27 in the Southern Climate Zone.  SHGC is improved with glass coatings that reduce the amount of transmitted solar infrared radiation.

Low Emissivity (Low-E) technology - molecular coating of silver applied to the inside of the glass (like a mirror, only invisible) reflects UV and Near Infrared (radiated heat).  Different manufacturers use 1, 2, or 3 layers of silver molecules.  The first number in the glass code indicates how many layers, the last two numbers indicate how much visible light is transmitted (LoE 240 has two layers of silver and only allows 40% light transmission).

Cardinal sponsors Windrose, Texas case study showing 25% cooling energy savings with LoĒ² glass.

LoĒ³-366^® by Cardinal offers the most visible light transmission while minimizing harmful UV and Near Infrared (radiated heat)
SHGC: 0.27 / U-FACTOR: 0.24 / TDW: 0.43 / LIGHT TRANS: 66%
http://www.cardinalcorp.com/products_coated_366/366.htm

Other Low E glass options:
LoĒ²-270^® Glass Solar control for all seasons SHGC: 0.37 / U-FACTOR: 0.25 / TDW: 0.53 / LIGHT TRANS: 70%
LoĒ²-240^® Glare Control Glass SHGC: 0.25 / U-FACTOR: 0.26 / TDW: 0.35 / LIGHT TRANS: 40%

1401 GREEN ROAD, SUITE I     POMPANO BEACH, FL 33064

Phone: 954-418-2186        Fax: 954-418-4485
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