Structural glazing and building design-a changing skyline

Structural glazing and building design-a changing skyline

Featured Article
19 Nov 2018

As featured in Architects Datafile - 2016

When you take a look around UK cities, the skyline is peppered with cranes. Be it the construction of high-profile commercial office blocks, such as the XYZ building in Manchester, or prestigious residential developments such as Spire London – set to become the tallest residential building in the UK – our skyline is changing.
 
Glass remains one of the most common components in the creation of these properties and here, Phil Savage, commercial sector manager at Pilkington United Kingdom Limited, discusses the growing importance of glass in modern building design.

Architects continue to incorporate glass into their designs to make a statement in the built environment. Iconic buildings across the world, from The Louvre in Paris to London’s Gherkin, act as a powerful example of the physical and aesthetic effect the material can have on the urban landscape. 

The ability to create larger and more impressive glass structures over the years has developed in line with technological and engineering improvements, and arguably one of the most significant architectural innovations of modern times has been the development of structural glazing systems. 

These systems give architects a flexibility that has previously been unimaginable, as they now have the ability to create buildings that appear to have been constructed solely of glass. Not only does this enable the creation of more imaginative and unique designs, it can offer a visually-striking alternative to traditional brick, timber or steel-reinforced concrete.  

How it works

The structural glazing systems available on the market today typically work by using stainless steel fittings that are countersunk into recesses in the corners of the glass, allowing strengthened panes to stand otherwise unsupported. The glass is then fixed to the structure of the building itself, rather than being fitted within traditional and sometimes view-restricting frames.   

With a range of options available, architects are able to choose the system that best suits the specific criteria of their installation and ultimately allows them to create their desired finish and performance. Glass-fin (mullion) units, for example, are among the most popular where a seamless finish is required.

The use of glass-fins eliminates the need for traditional metal mullions, which can restrict the view from inside a building. The transparent fins support the vertical façade and provide additional strength and integrity against the elements. Stainless steel fittings hold the structural elements together to create a strong, secure building envelope without compromising on the transparency or the external view. 

Added performance 

As well as being a popular choice among architects for the aesthetic results it can create, structural glazing also offers a number of other benefits too. Advances in coating technology mean that glass can increase a building’s energy-efficiency, helping to control its temperature or reduce glare. 

If the façade is south-facing, for example, solar control glass can help to prevent overheating inside a building, and reduce the expense of running air-conditioning units. Today’s technology also means glass manufacturers can now produce solar control glazing with very high levels of transparency, which allow maximum levels of daylight to be transmitted into the building without compromising on performance.  

On the flip side, in colder climates - where keeping buildings as warm as possible is a priority - structural glazing systems can employ the latest low-emissivity technology to achieve near-optimal thermal efficiency. The same system can also be double- or triple-glazed for even better thermal performance.  

Not only does this maximise internal comfort levels but it also helps to reduce the cost of energy bills.

Redefining glass’ potential 

Advancements in technology and improvements in engineering have meant the glass structures designed and built today are on a larger scale and are visually more impressive than ever before. 

As we continue to see developments in this area of the built environment, and as glazing systems evolve with these changes, the material’s potential will continually be redefined for architects, and it will play a key role in the creation of high-performing, sustainable cities of the future.  

CASE STUDY - Pilkington Planar™ makes a powerful impression in Washington DC building

The atrium of a commercial building is one of its key selling points. It is often its first impression with prospective investors, tenants and other visitors, so it needs to impress.

It was with this in mind that developer Boston Properties and architect Duda Paine Architects specified the 10-storey, almost-35-metre-tall glass façade that fronts the atrium at its landmark 601 Massachusetts Avenue project in downtown Washington DC.

The objective was to create a wall of glass that delivered maximum transparency, with minimum vertical elements, so that the whole atrium felt as much like an outdoor space as possible.

This was achieved using the Pilkington Planar™ point-supported glazing system to secure panes of up to 1.5m by almost 3.5m of 12mm Pilkington Optiwhite™ true low-iron glass to a series of 26-metre-wide one-piece horizontal trusses spanning the atrium. Additional vertical support was provided by low-profile stainless steel tension rods. A total of 970 sq m of glass was used, weighing around 29 tonnes.

The low iron content of the glass means it has exceptional clarity, without the pale green tint present in standard float glass. The clean lines were further enhanced by ensuring the glass was manufactured within extremely tight tolerances in terms of roller-wave distortion – the maximum ‘peak to trough’ variation allowed was just 0.02mm, creating an almost perfectly flat surface delivering undistorted reflections of the building’s surroundings.

The 905-series stainless steel bolts that connect the glass with the structure sit perfectly flush with the glass, maintaining the uninterrupted surface.

The multi-million-dollar 601 Massachusetts Avenue development features 44,400 sq m of high quality office space. The scheme has received Leadership in Energy and Environmental Design (LEED) Gold certification, demonstrating environmental responsibility across the design, construction, operation, and maintenance of the building.