Glass Faade

Introduction

Glass is becoming an essential component of many facades. This material is easily shaped and installed, allowing for the creation of gripping and dominating structures. However, a contemporary construction must meet a number of criteria in addition to esthetic standards to create enough comfort within a structure. It is vital to imagine a structure with an interactive shell to improve occupant comfort by increasing the quality of interior space and optimizing natural resources[footnoteRef:1]. Modern glass constructions have progressed from single-layered framed window glazing to load-carrying, high-performance structural elements that significantly impact modern architectures aesthetic attributes. Due to the complexities of using glass elements in modern buildings, several faade consulting considerations must be made to achieve a high-quality solution[footnoteRef:2]. Therefore, this paper seeks to determine the various attributes of glass facade and further elaborate the discussion by case analysis of The Shard glass facade. The discussion will cover why glass is used in facades, the history of using glass facades, the benefits and attributes of glass facades, and the sustainability features. [1: Jelena Savi?, Danijela ?uri?-Mijovi?, and Veliborka Bogdanovi?. "Architectural glass: Types, performance and legislation."Facta universitatis-series: Architecture and Civil Engineering11, no. 1 (2013): 35-45.] [2: Muhammad Tayyab Naqash, Antonio Formisano, and Ehsan Noroozinejad Farsangi. "Structural assessment of glass used in faade industry." InStructures, vol. 33, pp. 4817-4827. Elsevier, 2021.]

Background

Glass is one of the earliest manufactured materials that has been used continuously since its inception. Although the exact period of glass history is unknown, the earliest date discovered is 7000 B.C., during the Neolithic period. It was first employed in Egypt for decorative purposes before 3000 B.C., primarily as a colorful glaze on stone, pottery, and beads, but Romans pioneered its use in windows[footnoteRef:3]. A glass facade must have coincided with the change from conservative brick and concrete wall to a curtain wall. In the early years of the 19 century, there was a progressive shift away from traditional load-bearing masonry toward a framed structural system with steel and concrete parts[footnoteRef:4]. This gave rise to the possibility of replacing a masonry facade wall with a lightweight, transparent one. Because the facade on framed constructions no longer had a bearing duty, the facade wall took on the job of a faade window. The development of lightweight facade systems began and progressed simultaneously with the development of the skeletal system. [3: Alice T.Friedman, American Glamour and the Evolution of Modern Architecture. New Haven, CT: Yale University Press, 2010.] [4: D. D. Mijovic, D. Milanovic, and S. Jelena. "Curtain walls: history and a continuing challenge." InXVIII Int. Sci. Conf." Construction Archit. VSU 2018, pp. 1-6. 2018.]

The Crystal Palace (figure 1 below), built by Joseph Paxton in London in 1851, heralded a shift in architectures customary opaqueness by introducing transparency through the glass. He took glass from the greenhouse into the architectural domain for the first time. One of the main goals of this project was to create a consistently lighted indoor area using daylight as the sole source of light. As a result, translucent screens of calico were hung externally in-between the ridge beams of the roof glazing. They covered the whole surface of the highly exposed horizontal section of the roof to reduce the harsh sunshine and glare caused by this excessive transparency.

A

B

Figure 1: The Crystal Palace in London, 1851, shows glass faade, (A) Exterior and (B) Interior. Adopted from Mijovic, Milanovic, and Jelena[footnoteRef:5] [5: Ibid, at 2]

The idea of transparent, all-glass buildings piqued the interest of architects. Chicago architects constructed Americas first high-rise glazed building in the first half of the twentieth century. At the same time, Ludwig Mies van der Rohe of Germany envisioned and crafted models of hypothetical 20 and 30 story skyscrapers clad entirely in glass, resembling buildings today. Technology didnt allow for the building of multi-story glass facades like those on Bunshafts Lever House and Mies van der Rohes Seagram Building and the many other glass skyscrapers that make up Manhattans skyline until the middle of the twentieth century.

Benefits for glass faade

A glass faade provides a strong and weather-resistant exterior for the building. While some people may not realize it, the materials used in glass facades are exceptionally sturdy and long-lasting. Theyre built to withstand severe weather, such as heavy winds, rain, snow, sleet, and everything in between. Glass will not only repel these elements, but it will do so without altering its appearance. Unlike some other materials, it does not rust or otherwise erode due to exposure to the elements; thus, it will not be a problem for those constructions that employ glass.

A glass faade has a major benefit in delivering green buildings and conserving energy usage, especially lighting[footnoteRef:6]. This benefit is especially appreciated in large buildings where a significant fraction of energy consumption is in lighting. With a glass faade, a building will use the suns natural light to light up the buildings interior. In huge constructions, contemporary glass is amazing at managing temperature. Its wonderful to assist businesses in meeting the stringent commercial energy use standards. Itll become much more popular in the coming years as these regulations tighten in response to public demand. These two properties of glass can save a lot of energy that would otherwise be utilized for artificial lighting and temperature control. [6: Constro Facilitator, Glass facade; An overview of advantage and types. 2021, Deceber 7. ]

The other and probably the most important benefit of glass faade is the aesthetic value it confers to a building. Glass facades are some of the best-looking solutions available, in addition to being functionally strong and incredibly beneficial in a variety of practice areas[footnoteRef:7]. Glass building facades give off a sleek, modern vibe that appeals to a wide range of potential customers. The customizable pieces allow architectural designers to create any design building-owners choose, resulting in a modern aesthetic that will stand out from afar and up close. [7: Ibid]

Shortcomings of glass faade

Due to the high temperatures required for processing the raw materials, glass manufacturing is a very energy-intensive operation. Compared to the other materials used in construction, glass is a costly material. As a result, the overall cost of the structure may rise.

Glass is a fragile, stiff, and rigid material. When put under stress, it snaps without causing undue strain. As a result, glass is less impact-resistant, and its ability to endure an immediately applied load is limited. When it comes into contact with an object, it will immediately break. Glass is extremely hazardous in earthquake-prone areas[footnoteRef:8]. Unfortunately, there has been no technological innovation that can make Glass an earthquake-resistant material. It can, however, be adjusted to a degree so that it can resist small-scale earthquakes with some pricey treatment. Finally, broken glass can be exceedingly sharp, increasing the risk of injury. [8: Mehran Arbab and James J. Finley. "Glass in architecture."International Journal of Applied Glass Science1, no. 1 (2010): 118-129.]

Types of glass used in facades

Curtain wall

Curtain walls are non-load bearing curtain-like constructions linked to the buildings floor where the...…present the skyline with the aesthetic value it needed, thus making a glass faade the best option. Second, the structure is located in the neighborhood of the London Bridge, the Westminster Hall, and the Parliament Building. These structures hold a prominent position in Londons structural and architectural image of London and the U.K.; thus, it would go without saying that the visual value that comes with a glass faade was justified.

Disadvantages and advantages

The primary disadvantage of The Shards glass faade is that the exterior surface of the faade has to be cleaned manually, considering there are 11,000 panels of glass. This is a security concern for the glass cleaners, especially bearing in mind the cleaner who was left dangling on the 72nd floor when his cradle developed a mechanical fault due to high winds, a few days to the official opening date.

Despite this concern, the futuristic glass casing of the structure is triple-glazed and low-iron laminated, meaning it has a colorless low emissivity that reduces infrared heat loss. Computer-controlled roller blinds eliminate the need for air conditioning to avoid excessive heat buildup from solar energy. These glass fiber blinds are integrated into the glass facade and covered by single glazing, lowering solar radiation by 95%[footnoteRef:20]. When night falls, the blinds are rolled up to enable the days heat to escape. The Shards passive sun-shading mechanism has helped it to exceed the Part L directives 2006 standards by more than 25%. [20: Ben Hoskin, How the shard was built andthe problems they faced. (n.d.).]

The glass faade has provided Londoners with a spectacular birds eye view of their city. The Shard has a viewing gallery on the top floors, just below the spire, an advantage conferred by the glass faade.

The ultimate effects of using a glass faade

The ultimate effects of The Shards glass faade can be considered in four fundamental principles; wind, visual comfort, thermal comfort, and solar radiation[footnoteRef:21]. The inner atmosphere is separated from the outer environment by a glass facade for the building envelope. Differences in the two environments create environmental burdens. Temperature, moisture, and air pressure are the three most essential environmental loads. Both exterior temperature factors [i.e., outside air temperature, solar radiation, and wind] and interior temperature factors [i.e., occupant activities, ventilation, and heating equipment] contribute to temperature load. Therefore, the ultimate effects of The Shards glass faade are the architectural phenomenon and the aesthetic value achieved through the glass faade, which provides comfort to residents of The Shard and Londoners in general. [21: Mohamed Ahmed Alaa El Din Ahmed, and Mohamed Anwar Fikry. "Impact of glass facades on internal environment of buildings in hot arid zone."Alexandria Engineering Journal58, no. 3 (2019): 1063-1075.]

Technical drawings of glass fittings and techniques used

The Shards envelope is a double-skin passive system. This was required to meet the exceptionally high transparency requirement, which would have been impossible to achieve with an active double-skin facade with a mechanical ventilation system. Shard Cladding, Shard Skirt Cladding, Spire Cladding, Back-Pack Plant Cladding, Fracture Cladding, winter-garden Cladding, wing Wall Facade, Roof Steps, and Soffits, Lower Level Facade Curtainwall Systems, Canopies, Internal wall System Lobby, Steel-Framed Wall, Unitized Lower Level Cladding, Lower Level Louvre Cladding are among the fourteen different types of the facade on the Shard[footnoteRef:22]. [22: The Shard, Permesteelisa Group, (n.d.). < https://www.permasteelisagroup.com/project-detail?project=791>]

The technical aspects used in installing the glass faade are the unitized system (figure 8 below) and the double-skin faade (figure 9 below) integrated with blinds.

Figure 8: Unitized Glass Facade of The Shard, London. Adopted from Tijerina…