The right glass can be the centerpiece of a design concept. While low-E-coated conventional clear glass often is considered the basis of a design for many architects and other design professionals, it frequently fails to deliver the transparent aesthetic that inspired the façade design in the first place.
Clear glass is extremely common and is popular for a variety of architectural design applications, including vision glass, spandrel glass, storefronts, entryways, and other exterior uses. It is specified repeatedly due to its versatility and ability to serve as a substrate for solar-control, low-emissivity (low-E) coatings. In addition to its compatibility with low-E coatings, clear glass—sometimes referred to as “clear float glass, “conventional clear glass,” or “standard clear glass”—is also relatively inexpensive, and is frequently selected for its neutral color.
However, when specifying glass to achieve a desired aesthetic, most design professionals know that clear glass isn’t completely clear. When viewing a lite of clear glass, you may notice its slight green aesthetic, which becomes more pronounced when viewed from an angle and appears even darker at increased thicknesses or when used with low-E coatings. This can compromise the design intent, especially if the goal is to create a highly transparent façade or well-lit spaces with brilliant views of the outdoors.
Iron oxide content within the glass, left over from the manufacturing process, gives clear glass its green aesthetic. Experienced design professionals are all too familiar with this undesirable attribute. However, new innovations are addressing this design challenge from both an aesthetic and budget perspective.
Low Iron and High Performance
With its low iron content, low-iron glass significantly reduces the green aesthetic found in clear glasses, making it ideal for distinctive exterior applications where excellent clarity is required. For reference, Acuity low-iron glass by Vitro Architectural Glass is 60% less green than ordinary clear glass.
Low-iron glass is also an ideal substrate for low-E coatings, complementing the heightened clarity with outstanding energy performance. This combination allows designers to create highly transparent, high-performance exterior façades with brilliant interior views, high visible light transmittance (VLT) and true-to-life views of the outdoors.
A low-E coated low-iron insulated glass unit (IGU) typically consists of an exterior lite of low-iron glass with a low-E coating applied to the interior surface and an exterior lite of uncoated low-iron glass. This configuration can be specified for everyday applications, such as office buildings and institutions, hotels, schools, condominiums, and mixed-use buildings, as well as entrances and retail storefronts. low-E coated low-iron IGUs also can be leveraged for distinctive daylighting applications, such as atriums and skylights.
Fabricated glass costs are an important consideration in the façade design process. Market research indicates the installed cost of a standard glass-and-metal curtainwall averages $90 per square foot, nationwide. While the prospect of upgrading from coated clear glass to coated low-iron glass may raise budget concerns by some project stakeholders, new advances by glass manufacturers have helped bring transparent, high-performance façades within reach.
For example, upgrading a low-E-coated clear IGU to an IGU with Solarban Acuity glass by Vitro Architectural Glass typically will increase the total installed curtainwall cost by only $1 to $2 per square foot. This optimization of cost, clarity, and performance allows design professionals to make low-iron glass an integral focus of their façade designs.
Commercial building design is often an exercise in balance—between performance and aesthetics and budget and quality. Fortunately, options are available today that allow design professionals to avoid compromise and retain their original design intent.
Get less green, for less green. Request samples of Solarban Acuity glass at vitroglazings.com/acuity. Choose from two customizable sample kits to assist with product evaluation.