WHY IS IT IMPORTANT TO SPECIFY WHICH TYPE OF GLASS ?
The most crucial part of a successful project is choosing the right architectural glass. To learn more about the decisions in the evaluation, specification and selection of architectural glass, GSW Glass ( partnered with Saint Gobain Glass ) recommends that each customer becomes familiar with the properties and benefits of the most common glass types: clear glass, low-e glass,tinted glass and low-iron glass.
The most common used type of glass is known as clear glass and it is available in a variety of thickness. It has high visible light transmittance and reasonable color transparency and neutrality, though its green hue intensifies as the thickness increases. The performance and color of clear glass usually varies by manufacturer due to a lack of a formal color or performance specification defined by ASTM International.
Low-E Coated Glass
Coated vision glass was introduced in the 1960’s to reduce heat gain from the sun and to expand aesthetic options. Low-emissivity or “LOW-E” coatings are made of metallic oxides. They reflect any long-wave energy from the surface of the glass, minimizing the heat passing through it.
Low-e coatings restrict the amount of infrared light and ultra violet that can pass through glass without compromising the amount of visible light transmitted. When heat or light energy is absorbed by glass, it is either shifted away by moving air or re radiated by the glass surface.
Created by incorporating a minor admixture into the glass during manufacturing, tinted glass provides neutral warm or cool-palette colors, such as blue, green bronze and gray. It also features a wide range of tints from light to medium to dark without affecting the basic properties of the glass, though they do affect heat and light transmittance to varying degrees. In addition, tinted glass can be laminated, tempered or heat-strengthened to satisfy strength or safety requirement. Much like clear glass, the color and performance of tinted glass varies by manufacturer because no ASTM color or performance specification for tinted glass exists.
Reasons to Specify Clear Glass
Clear glass is widely specified because of its low cost due to its use of recycled material. It’s an excellent substrate for high performance low-e coatings and in a variety of thicknesses, from 2.5 millimeters to 19 millimeters. It is an excellent substrate for high performance low-e coatings.
Application types for clear glass include insulating glass units (IGUs) and windows, as well as doors, mirrors, laminated safety glass, interiors, facades and partitions.
Reasons to Specify Low-E Coated Glass
Ideal for heating-dominated climates, passive low-e coated glass allows some of the sun’s short-wave infrared energy to pass through. This helps heat a building, while still reflecting the interior long-wave heat energy back inside.
Ideal for cooling-dominated climates, solar control low-e coated glass blocks solar heat energy and provides thermal insulation. This keeps cool air inside and hot air outside. There are many benefits of energy-efficient coated glasses, including increased occupant comfort and productivity, management of daylight and glare control. Low-e coated glasses allow the building owner to better manage energy consumption by reducing reliance on artificial heating and cooling, leading to long-term cost savings.
Reasons to Specify Tinted Glass
Tinted glass is ideal for any project that can benefit from added color that harmonizes with the overall building design and site features. Tinted glass is also beneficial for reducing glare and limiting solar heat gain when used in conjunction with low-e coatings.
Some applications for tinted glass include IGUs, facades, safety glazing, spandrel glass and single-lite monolithic glass. Tinted glasses can be produced with low-e coatings for additional passive or solar control performance. Tinted glass can also be laminated, tempered or heat-strengthened to satisfy strength or safety glazing requirements.
Reasons to Specify Low-Iron Glass
Low-iron glass is typically specified because it features a percent of the iron content of regular glass, allowing it to transmit 91 % of light compared to 83 % of regular glass, without the greening effect associated with clear glass panels. It also features a high degree of color fidelity and clarity.
Low-iron glass is ideal for security glazing, safety, protective windows and doors and safety barriers. Specified for interior elements such as fish tanks, balustrades, spider walls, shelves, tabletops, doors and back splashes. Exterior applications include skylights, entrances and storefronts and vision glazing.
Low-iron glass is made with a formulation that gives it heightened levels of clarity and transparency compared to traditional clear glass. Because there is no ASTM specification for low-iron glass, clarity levels can vary widely based on how they are manufactured and the levels of iron found in their formula.