Glass Facades: Selection & Performance Criteria

<p style="text-align: justify;">One of the most noticeable trends in commercial real estate industry globally, has been usage of glass for facades of the buildings. Glass definitely makes the building look elegant, at the same time, provides comfort to the occupant with enhanced visibility, thermal and acoustic performance.</p><p style="text-align: justify;">This article focuses on key aspects of a glass fa&ccedil;ade &ndash;Energy efficiency, acoustics, security and aesthetics. For ease of understanding and to maintain focus on the core topic of this discussion, I have overlooked the regulatory requirements of glazed facades and focused solely on their characteristics for effective selection.</p><p style="text-align: justify;"><strong>Energy Efficiency</strong></p><p style="text-align: justify;">Building an air-tight, highly insulated glazed fa&ccedil;ade requires careful detailing and precise material selection. For a building to achieve the highest levels of efficiency, it must be fitted with low-e glazed IGUs, preferably filled with heavy argon (most common) or krypton gas. Today, glazing systems are manufactured to transmit an adequate amount of visible light while minimizing heat gain. Here are a few factors that impact the performance of the fa&ccedil;ade:</p><p style="text-align: justify;">▪ Solar Heat Gain Coefficient (SHGC)<br />▪ Visual Light Transmittance (VLT)<br />▪ U-Value</p><p style="text-align: justify;"><strong>Acoustics</strong></p><p style="text-align: justify;">With the proliferation of high-rise glazed buildings in noisy urban areas, prescribed acoustic requirements have become a prevalent concern in designing building envelopes. Several classification indices, including Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC), are used to evaluate the acoustical performance of architectural products.</p><p style="text-align: justify;"><strong>Security</strong></p><p style="text-align: justify;">In the last few decades, security concerns have attained dominance over other considerations involving protection against human-initiated and natural catastrophic events.</p><p style="text-align: justify;"><strong>Aesthetics</strong></p><p style="text-align: justify;">The type of glass one selects for the facade is an avenue through which identity of a bespoke glazed fascia for the building is created. These include, but are not limited to, clear or tinted glass, fritted glass, etched glass, mirrored glass, reflective glass, patterned glass and channel glass.</p><p style="text-align: justify;"><strong>Products</strong></p><p style="text-align: justify;">For large facades, reflective glass is a majorly used element. These days, the spectral selectivity of the coatings is engineered at a molecular level. So, coatings can be applied for reducing heat gain, while still remaining relatively clear or to offer a broad range of reflectivity and color, providing more aesthetic choices. Along with the conventional pyrolytic and soft coated glass, following are some recent inductions to the glass bouquet:</p><p style="text-align: justify;">▪ Low-E Glass<br />▪ Building Integrated Photovoltaic (BIPV) Glass<br />▪ Low-iron glass<br />▪ Dynamic / PDLC / Electrochromic Glass</p><p style="text-align: justify;"><strong>Geometric Customization</strong><br />Architects prefer to create complex geometric glazed fa&ccedil;ades that demonstrate that the possibilities for aesthetic customization are endless. Glass is not the delicate, inflexible material that it used to be. Improvements in the manufacturing process have made it stronger, purer and thinner than ever before. These high-strength sheets can be shaped by machines, in specialized furnaces or on site, without breaking; enabling architects to create sculptural glass buildings. These fa&ccedil;ades bend, twist and undulate.</p><p style="text-align: justify;"><strong>Afterword</strong></p><p style="text-align: justify;">Undoubtedly the greatest benefit glass offers today to architecture is transparency that no other cladding material can offer, to make the walls invisible and provide a connection to the outer world. With the profound advantages of Glass as an important building material, the need of the hour is to build smart and sustainable facades.</p>
KR Expert - Ashit Kansara