Emissivity refers to how efficiently a surface emits thermal energy.
Low Emissivity Glass (or Low-E) coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow. Low-E coatings come in hard or soft and are designed to help trap in heat by reflecting the heat back. During colder temperatures in colder climates, its recommended that insulating units are designed with the coating facing inward to prevent excess heat from escaping.
A pyrolltlc (or Hard) Coat is designed to reduce heat loss but admit solar gain. This Low-E glass type is also the product of choice for passive solar design projects.
A sputtered (or Soft) Coat is designed to reduce heat loss and let in a reasonable amount of solar gain and are suitable for climates with both heating and cooling concerns.
|Glass Type||Visible Light||Reflectance||U-Value||Shading-Coefficient|
|Winter Night||Summer Day|
|Sunqate 500 – Pyrolitic (Hard) Coat||74||14||0.35||0.35||0.71|
|Solarban 60 – Sputtered (Soft) Coat||70||40||0.29||0.28||0.47|
|Based on two 1/4-inch Clear Interior (6mm) Lites with 112 Airspace|
High Performance Low-E
Guardian ClimaGuard- Soft Coat
Guardian Neutral 70
PPG Solar Ban- Soft Coat
ACG Comfort Select
Pilkington Energy Advantage