This may be helpful for some to understand the difference.

Low-E (low-emissivity) glass is coated with a low-emittance material designed to reflect heat. A window made with Low-E glass repels ultraviolet rays that generate heat during the summer but absorbs UV rays and let’s heat in during winter. The better insulated the window glass, the more comfortable your room temperature.

Low-E 180

With a glass U-Factor of just 0.26 and an SHGC of 0.69, Low-E 180 Glass is an excellent basic product for passive solar applications. By blocking heat loss to the outside of the glass, the high solar gain glass keeps homes warm in winter and cool in summer.

Low-E 272

 Low-E 272 Glass delivers year-round comfort, reflecting an intermediate level of heat back into the room in winter and rejecting the sun’s heat and uv rays in summer. This product’s patented coating provides clarity and high-performance low-solar control, reducing window heat gain by 50% compared to ordinary glass.

Low-E 366

The ultimate performance glass, Low-E 366 provides the highest levels of year-round comfort and greatest energy savings. Its patented coating offers an ideal balance of solar control and high visibility. Blocking up to 95% of the sun’s damaging rays, Low-E 366 glass sets a new standard in energy performance.

 

How Low-E 366 Glass Works

Low-E 366 consists of two panes of insulated glass filled with argon. The inside of the exterior pane is coated with a triple layer of silver, providing a high level of solar control along with high visibility.

Dual Low-E glazing combines Cardinal Low-E 366 soft coat on the inside of the exterior pane (surface 2) with Cardinal i89 coating on the inside of the interior pane (surface 4). The Cardinal i89 coating is a durable, low emissivity coating that gives the product improved thermal insulation performance compared to clear insulated glass or standard Low-E insulated glass.

Thank You,
Troy Jantz