Man’s fascination with glass architecture is nothing new. As far back as the Romans, windows were being used as architectural components, and frames were finished with thick green/blue-cast glass and implemented as a form of conservatory for growing vegetables. But it is not only the functional aspects of the material that have been drawing architects’ attention for thousands of years; glass also has an artistic and philosophic purpose to which no other building material can lay claim.
"It’s the only material with which we can explore spatiality and interior architecture," says Brent Richards, creative director and CEO of the Design Embassy Europe. "The idea of being able to see both inside and outside has always been a fascination."
But it is only recently that architects have been able to use glass on the scale they have been dreaming about for so many years.
"It’s not that it’s suddenly become popular," Richards, author of New Glass Architecture, explains. "What’s happening at the moment is a convergence between industry, affordability and people’s everyday understanding of the material. There’s an architectural and artistic symbiosis between the technical possibilities of what the industry can provide and what the commissioners can afford. Since 2000, those things have developed."
Balance of facets
While the past 40 years have seen huge developments in glass technology – from the size of the sheets to the types of coatings used and the ways in which the panels can be connected – it is really only in the last ten to 15 years that architects’ understanding of glass has increased to the extent that they can now control how the material performs.
"There is still this question of affordability, but essentially I think we can now say that we can control the environmental aspects of glass," says Richards. "We can control performance and sustainability in order to create an all-glass building that is carbon neutral and therefore sustainable.
"You have a whole range of possibilities – interlayers, different gases, coatings on different sides of the glass," he continues. "You can change the characteristics of the glass either environmentally or artistically in terms of colour and texture, and you can control the type of light that comes in."
For Robert Whitlock, a principal at KPF, Richards’ final point is key.
"So many things contribute to the efficiency of an office building," he says. "You’re trying to keep the radiation out but let daylight in. In an attempt to have a high-performing building, there’s a constant balance between keeping light out to cut down on the solar load and letting enough light in to reduce reliance on artificial illumination."
In order to achieve this balance, collaboration with manufacturers is absolutely crucial.
"It’s remarkable how far the industry has come in customising coatings," Whitlock says. "We now have dialogues with manufacturers to tweak the performance – shading co-efficient vs value vs the amount of reflectivity, as well as the colour of the glass. It’s like a big recipe to fine-tune these coatings so that they perform the way we need them to relative to the environment they’re in."
At Hysan Place, a mixed-use retail and office development in Hong Kong, and the region’s first LEED Platinum pre-certified commercial project, KPF used several different strategies to achieve the precise performance required.
"We had a light shelf in the curtain wall with a portion that projected out from the glazing, acting as a sunshade," Whitlock explains. "It also had a component inside that was configured to bounce light back into the deeper parts of the office space using the ceiling as part of the reflecting surface. We were also able to test different shading co-efficients above and below the light shelf to try and optimise performance of the entire envelope."
The glazing system used by the team at RMJM, which designed the iconic Capital Gate tower in Abu Dhabi, is similarly complex. "The Cardinal glass LoE²-240 blocks 84% of harmful UV radiation," says Jonathan Knight, international design principal at RMJM. "It absorbs 60% of the visible light, which gives the coating glare control and its soft, muted-blue colour. It reflects nearly all of the invisible infrared rays."
The Cardinal façade is 51% more efficient at restricting solar heat to a building than a standard façade, reducing the energy consumption of the HVAC system by 15%, according to RMJM managing principal Chris Jones. "The façade uses natural light to the full and with the type of glass used, the Cardinal LoE²-240, it blocks the UV and infrared radiation, and permits visible light," he adds.
Glass’s natural properties also contribute to its environmental credentials.
"It’s a natural material made from natural substances that can be crushed, recycled and remade continuously, although you have to take into account that you also need to fire up a furnace and that most glass production has to be a continuous flow process," Richards says. "But if you accept that limitation, you’ve got a fantastic sustainable material."
Yet Richards is just as keen to emphasise that the sustainability of a building is holistic.
"There’s the performance of the building in terms of energy use and there’s how you construct the building," he says. "But on top of that, once you’ve constructed it, you need to consider the building’s entire lifecycle. Does it pay back in terms of creating energy for you, controlling your environment and developing well-being?"
Fortunately, glass unequivocally ticks the final box.
"Obviously glass buildings require an investment because they’re very technical and complex, but once you’ve got them up, they perform for you," Richards says. "Glass is a quick reactor. If you’ve got a stone or a brick building, it tends to warm up and lose heat very slowly, whereas a glass building reacts quite quickly. So, as long as you understand that reaction time, you can use it to your advantage."
For Whitlock, it’s that understanding of how the material can be used that is really going to contribute to the success of future glass developments.
"With subsequent projects, it’s going to become easier to get into it faster and do it more quickly," he says.
But the understanding goes far beyond the comprehension of how the physical characteristics of glass work together to create an energy-efficient building. Richards is currently working with the University of Oxford in the UK to prove that living and working in a predominantly glass building can actually improve health and well-being.
In the next ten years, the industry’s technology is set to develop to the point where glass coatings can change its state relative to the environment.
"There are also products being tested that change an inert gas in the cavity of an insulated glass unit from invisible to cloudy, providing privacy or shading – this is typically achieved through an electrical current," says Whitlock.
Going still further, some industry members are looking at the idea of gestural language.
"You will be able to gesture to the building and it will respond to you," Richards explains. "For example, in an area of outstanding natural beauty, you would be able to increase your connectivity to nature. We believe that if we can increase the dosage of natural, rather than artificial, light, your health and general well-being will benefit, and that’s really exciting."
Architects will be able to apply this to buildings such as schools, other learning environments and spas.
"We’ll be able to say there’s another reason for building glass buildings," says Richards. "Not only because of aesthetics, the design and because we like to be able to see the garden, but because it’s fundamentally better for you than living in a cave."
This article was first published in our sister publication The LEAF Review.