Glass is phenomenal, and ambiguous. Early Modernists regarded it as the super material.
Glass was the means by which to reunite man with nature, as designers ignored practical needs in search of the perfect domestic goldfish bowl. Today they continue to struggle, battling to understand its environmental credentials, resolving inherent contradictions to justify morally the use of a material that, while bringing daylight to interiors, concurrently exposes them to thermal, optical and practical complexities.
Attempting to explore these complex issues, this year's Architectural Review annual conference (held at the RIBA on 5 March) sought to look deeper into transparency. The subject, it would seem, continues to frustrate.
Michael Wiggington, chair of architecture and design at Plymouth University and author of Glass in Architecture, began by discussing the history of glass. From Roman to recent times, he traced the material's evolution - small openings, large openings, glass houses, curtain walling - concluding with a curious and perhaps unintentional contradiction. Having presented glass as the 'universal container' - transparent, rigid, impermeable - his final slide illustrated the ideal physical envelope: human skin - translucent, flexible, permeable. With this he had demonstrated succinctly the inherent shortcomings of glass. Glass may be the 'universal container', but it will never be a 'universal skin'. It cannot flex, stretch or, most significantly, breathe.
Most innovations in glass have focused on how it is fixed, held or restrained. Its ability to moderate the internal environment always relies on secondary components: blinds, actuators, gaskets, leaky frames, slot ventilators; the list goes on. As demonstrated clearly by the three contributing engineers - Tim MacFarlane, Tony Hunt and Stephen Engelsmann - the pursuit of transparency has always relied on how glass is engineered.
From column-and-frame solutions to filigreed glasshouse structures, curtain walling to cable nets, the nature of the structure has more of an impact on transparency than the nature of glass itself. Even when glass is exploited structurally, it is the mastic, glue and bolts that become the focus of attention.
So, when questioning the nature of transparency as an architectural phenomenon, what more is there to be said? Is the history of architecture defined by the history of making holes in walls - leaded, framed, frameless, bolted or suspended? How many variations of the spider bracket must we endure?
Fetish of detail In the presentations, Eva Jiricna's work was consistently delightful; however, transparency did not appear to have been her key concern. And Helmut Jahn's work, as impressive as it was in terms of scale and ambition, was neither sensorily nor conceptually rich. The fetish of detail often distracts, and in pursuit of a transparency that does not rely on exposure to acres of glass, it is worth remembering that, in opposition to the more expressive work of many, few have produced more delightful and modestly framed apertures than Barragán, Utzon or Sverre Fehn.
James Carpenter and Luke Lowings were perhaps the only contributors to tackle fully the nature of transparent materials. Fundamental to their approach was the notion that glass - or in fact any translucent or transparent architectural elements - should never be considered as void or residual to more massive opaque materials. Glass, foil, plastics and mirrors can be as substantial visually as brick, steel and stone. Therefore, the way that surfaces relate to each other and the spaces they contain should be composed carefully.
We should, based on site-specific data, continue to evaluate the qualities of glass.
How deep or how reflective should a surface appear? What is the boundary and how should it be projected? How can glass encapsulate visual information, hold reflections or project shadows? And how can glass translate the viewer's perception of a space?
By experimenting with gradients of opacity, colour, artificial lighting and specific angles of incidence, potentially formless transitional spaces such as atria and stair cores can adopt specific characteristics.
As a consultant designer brought in to refine and extend the original architectural concepts, Carpenter/Lowings Architecture & Design has worked with many leading design teams and demonstrated more than anyone else that creative specialism is as significant as technical expertise when considering transparency.
Transparency is about our perception of positive stimuli, not about invisibility. The word 'dematerialisation' should be banned.
Glass is not void.
Rob Gregory is an architect and assistant editor of the Architectural Review