Reduce Your Energy Costs with Energy Efficient Windows

Understanding a Window’s Performance

Understanding all of the factors in a window’s energy efficiency can be difficult.
What do terms like Energy Star, Low-E and SHGC mean, and how do they affect your comfort and your heating and cooling bills?

Here’s a brief overview of the important factors in energy efficiency.


Thermal Performance of the Entire Window


ENERGY STAR was created by the United States Department of Energy to establish a program for evaluating the thermal performance of windows and their suitability for different geographic regions of the country.

Windows must be tested to the National Fenestration Rating Council (NFRC) standards. Windows must be certified by an independent third party as meeting the NFRC test standards and unbiased criteria set by ENERGY STAR.

Seaway offers a variety of glass configurations, including those that meet the criteria for each ENERGY STAR region.


All Seaway windows with low-E glass meet & surpass these criteria and are available to meet ENERGY STAR criteria in all climate zones.


The U-Factor indicates how easily heat will flow through the window, whereas R Factor indicates the opposite: how well the window will resist heat flow. The lower the U-Factor, the better a window insulates.


Solar Heat Gain Coefficient (SHGC) is the amount of solar radiation admitted through a window. The lower a window’s SHGC, the less solar heat is transmitted into the house and the easier it is to keep your house cool in the summer. On the other hand, in northern climates, a higher SHGC can provide beneficial passive solar heating in the winter. Seaway offers a variety of high-performance glass coating packages with varying SHGC ratings to suit your needs, based on your climate.


Seaway’s spectrally selective glass coating packages have been designed to enhance a window’s thermal performance by blocking ultraviolet and infrared light, and in turn, block some visible light as well. Clear glass blocks about 20% of visible light.


The amount of air that can pass through the seals of a window’s operating sashes, measured by a fraction of cubic feet per minute per square foot of window at 25 mph winds.


Not All Low-E is Created Equal

Seaway’s high-performance Low-E is our standard Low-E, and has a double thickness of silver and a hard outer layer of titanium to provide extraordinary performance in climates where reducing both heating and cooling costs are important.

Seaway’s high-performance Low-E has a clear appearance with minimal tint, yet it can keep the summer heat and the winter cold outside, giving you year-round comfort.


Intercept™, Ultra InterceptTM and Super Spacer®

Seaway uses advanced Intercept™and Ultra InterceptTM technology as a standard to create insulated glass with a warm edge around the perimeter. The edge of the glass is typically the coldest spot on the window and can be prone to condensation.

Other windows utilize glass panels with rectangular aluminum spacers, which conduct the heat away from the inner pane of glass resulting in a cold edge. Intercept spacers, instead, use a thin steel U channel that reduces conductivity and keeps the edge of the glass warm.

Seaway also offers Super Spacer®, a non-metallic structural foam spacer, as an option for the absolute finest in warm edge spacers.

Super Spacer blocks heat escape, dramatically reduces condensation and offsets the effects of temperature changes that create stress cracks.


Gas Fill

All Seaway windows with high-performance Low-E glass receive argon gas fill between the panes of glass. Krypton gas fill is available as an optional upgrade. Argon and krypton are harmless and odorless rare earth gases that are found in minute amounts in the air.

When concentrated, argon and krypton gas are more dense/viscous than air, reducing the convective heat loss from between the glass panes and have lower thermal conductance, thus reducing conductive heat loss through the glass unit itself. Many companies charge extra for argon gas, or use less of it to save costs, but Seaway uses a minimum 90% fill level and includes it in all our standard high-performance Low-E packages.

Seaway’s Insulated Glass Packages

All Seaway windows are offered with a wide assortment of high performance of glass packages. You can choose the glass package and thermal glass performance that best suits your climate and comfort needs.