Glass Types (Part One)

When buying windows you may hear a lot of numbers and letters being used to describe glass types.  There are a lot of glass types.  The most common glass options for windows include;

• Low-E Coatings (180, 272, 366)
• Tinted Glazings (colors or reflectives)
• Privacy Glazings (obscure)
• Safety Glazings (tempered, laminated, lexan)

Marvin's standard glass offering is Low E II (2) with argon.  Low-E is the most common glass type used, so we'll just focus on those today.  Marvin offers multiple types of Low-E glass;

• Low-E 2
• Low-E 3
• Hard coat Low-E
• Low-E (180)

What the heck is that, you ask?

Low-E (LoE ) stands for low emissivity.  The lower the emissivity, the higher the percentage of long wave radiation blocked -which improves thermal performance.  It is coated with a thin, virtually invisible, metal (silver) or metallic oxide layer.  The primary function of this is to reduce U-factor by suppressing heat flow.  A secondary feature is blocking radiation to prevent heat gain.
There are two basic types of LoE glass; softcoat (see Low-E 272) and hardcoat, or pyrolitic LoE.

Soft Coat refers to an electrostatically sputtered application onto the cool glass surface #2.

Hard Coat or pyrolitic LoE: designed to be used either in non-sealed applications such as single glaze (surface #2) or exposed surfaces (#4) or for insulating glass applications that require a fourth surface coating.  Hard coat is applied to a semi-molten glass surface and has a slight haze and requires special cleaning.

Surfaces?  Yes; the double paned glass that most windows are today have the surfaces of each pane numbered from the outside in.  The inner most surface being 4, the outter most being 1.

Argon gas?  Yes, a colorless, odorless, inert gas used between the glass surfaces to reduce convection and conduction (expansion/contraction) and to increase efficiency.

Low-E 2 (272) is a high performance Low-E glass.   The 2 refers to the number of layers of coating (silver).  The 72 indicates the percentage light transmittance of the glass.  This provides excellent winter and center of the glass temperatures, in addition to keeping customers cool in the summer.

Low-E 3 (366) is a very high performance Low-E glass.  This provides the best winter U-factor and center of glass temperatures.  It offers extremely low solar heat gain which provides customers with very cool summer glass temperatures.  366 provides the best reduction in UV light transmission.  It has (3) layers of coating and transmits 66% of visible light through.

U-factor:  A measurement of the amount of heat flow through a product.  The lower the U-factor, the greater resistance to heat flow and better it's insulating value.  U-factor values generally range from 0.25 to 1.25 and are measured in Btu/h·ft²·°F.

For more information on energy basics you can always visit us at http://www.marvin.com/benefits-features/energy-efficiency-basics/