4 Factors – Determining Glass Energy Performance

Insulated Glass Units

The popularity of insulated glass continues to grow among residential and commercial property owners who are seeking a more energy-efficient solution for their homes and businesses.

4 Factors – Determining Glass Energy Performance

1. Visible Light Transmittance (VLT) – Measures the amount of visible light that passes through glass.
2. Solar Heat Gain Coefficient (SHGC) – The measurement of how well glass absorbs heat generated by sunlight.  Measured on a scale of 0-1, glasses with a lower SHGC value block out more heat from transmitting.
3. Light to solar Gain (LSG) – A measure of how well glass allows natural light to pass through while blocking out solar heat.  It is the ratio between the Visible Light Transmittance and Solar Heat Gain Coefficient and describes the relative energy-efficiency of glasses.  While not possible, the ideal environmental performance of glass would be to transmit 100% of the sunlight while absorbing 100% of the solar heat.
4. U-Value – The measurement of heat transfer through glass and other building materials.  Glasses with lower U-Values are better insulators.