The transparent trend that has been developing in architecture for more than 120 years is now in the stage of dynamic prosperity, although a distinct change can be seen. The “ideal” transparency that can currently be achieved in architecture is the result of a long process involving the development of material production technology and the methods of its installation (mounting and fastening). Contemporary architectural transparency (optical property of the material) is constantly being redefined, and over the last decade, new trends have begun to emerge. A question arises whether there is any connection between optical transparency and the institutional meaning of the term transparency, which is usually associated with government policies and corporation governance. Despite the recent shift towards picturesque surroundings, it is the optical properties of transparent materials which have “suffered” the most. What might seem as merely a linguistic/semantic trick of modifying the meaning of the word is in fact greatly affecting the real architecture, its relationship with people, and the way society perceives it.
Even early modernists knew that the light-transmitting envelope is optically transparent only in certain lighting conditions, while in the other conditions, the virtual image dominates over the real (transmitted) one
Convoluted paths of transparency
Since glass was first developed, its optical parameters have changed considerably. The manufacturing technology has greatly improved and what once was a foggy bulb of glass mass is now a smooth and flawless pane. Originally, the modernist glass was supposed to flood the interiors with light and free the people from the sad and dull reality of 19th century architecture, as “…modernist architecture used the agency of transparent glass to erode the distinction between interior and exterior space” (Shimmel 2013). I believe this – in those days – innovative attitude can be labeled as honest use of glass, despite the naivety of the predecessors of the modern movement. Visually, glass makes a building more volatile than a solid masonry wall with sculpted details. The application of glass, especially in the form of flat sheets, creates a deliberate optical effect, which results from the physical properties of all smooth surfaces. A pane that is smooth enough to transmit light without scattering can also create a virtual image (i.e. the reflection in the glass pane). This is the reason why Mies van der Rohe in his garden photographed a model of a famous glass skyscraper (Colomina 2007) to judge the prevailing optical effects that would create the image of the building.
The original honest transparency became a subject of theoretical considerations. Changes came in the 1940s and 1950s and culminated in the famous essay by Rowe and Slutzky titled “Transparency: literal and phenomenal”. Public found out that apart from “literal” (optical) transparency, there also exists “phenomenal” transparency (Rowe, Slutzky 1963). Although the paper did describe interesting figure-ground phenomenon it did not contribute anything new to the field of optical transparency of light-transmitting materials, but instead caused some confusion, which was then multiplied by numerous interpretations by other authors. As Haag-Blatter concludes her critique “literal and phenomenal transparency in no way provide us with a new general definition” (Haag-Blatter, 1978). The first part of the paper by Rowe and Slutzky became very sound and started the career of the notion of “transparency”, which is disassociated from its original optical meaning. As Shimmer writes, that papers by Rowe and Slutzky were “…influential in shifting the interpretation of transparency“ (Shimmel 2013) towards new post-modern meanings of blurred translucency and vagueness. This moved the new meaning towards more metaphorical, but still deeply thought-through visual design proposals. This happened to coincide with the development of material technology that allowed for new types of transparency.
Does smooth always mean transparent?
Even early modernists knew that the lighttransmitting envelope is optically transparent only in certain lighting conditions, while in the other conditions, the virtual image dominates over the real (transmitted) one. Optical transparency is a fragile property that is determined by many aspects of the surrounding environment. Basic glass simply does not guarantee optical transparency for all viewing angles. The phenomenon of overlapping real and virtual images was initially considered valuable, but soon – with the increased use of glass – the phenomenon became ubiquitous and common. The transmissive qualities of glass had also a negative impact on the microclimate due to the greenhouse effect. The ideology that was born out of the need for illuminated interiors suddenly turned to advanced technologies to reduce this illumination. At the time, excessive heat gain was defied by placing a microscopic layer of metal on the glass pane (i.e. a thin metal coating). It did temporarily solve the problem of overheating but it also permanently blocked the view into the building. Mirrored glass became eminent, especially in corporate architecture, where efficiency counts.
This visual change notably moves the public attention, and the honesty of the architectural glass application in buildings and its semantic meaning is questioned. The first associations are obvious and simple: optical transparency means that the building has nothing to hide, just as the company/government that occupies it. Transparency was a handy feature to consider: it was visually appealing and politically very sound. PR managers quickly realized that companies do not need to create a bona fide institutional transparency if they can simply give people the mere optical transparency to serve as a symbol. As Vidler rightly points “…the politics of the moment insisted, and still insist, on the illusion that light and enlightenment, transparency and openness, permeability and social democracy are not only symbolized but also effected by glass” (Vidler 1993). This strong yet unfortunate misconception is confirmed in many completed buildings. To name the two: the Foster’s renovation of the Reichstag’s Building (Fig. 1a) and Petzinka, Pink and Partner’s CDU political party headquarters (Fig. 1b). CDU building is encased in a transparent envelope that allows people to see the glazed hall, but not to penetrate into the office rooms, where the real politics happens.
The strive to achieve institutional transparency turns out to be a very dangerous path, as it allows the public to scrutinize the processes that were previously hidden. It might be speculated here that as contemporary institutions and corporations are becoming more and more transparent visually, they still remain inaccessible and vague as far as institutional transparency is concerned. This direct and simple glass equals honesty attitude to transparency was thoughtfully criticized and questioned. The extensive use of glass does not improve democracy, it rather raises more the questions than it actually answers. Optical transparency is considered “… a convenient marketing gimmick in sales pitches rather than a thought-through functional concept to be taken seriously” (Zinnbauer, 2015).
Transparency deliberately interrupted
Gradually shallower ideological convictions have replaced the original honest meaning of transparent architecture. The visual aspect of architecture has a new interpretation. It is not that glazed architecture was not visual before, but the pressures are distributed a bit differently. In 1995 Terence Riley in a catalogue of famous “Light Construction” exhibition claimed that “the facade becomes an interposed veil (…) distancing the viewer of the building from the space or forms within and isolating the viewer within from the outside world.” (Riley 1995). This trend of gradual erosion of transparency is widely seen, especially in the way the glazing technology develops towards the obscuring of transparency: printing, fritting, tinting the glass. This results in interesting formal and visual effects, where glass becomes a bearer of a completely new content. Previously, the obstruction of transparency resulted from the unfavorable lighting conditions or because of poorly performed installation job. Nowadays transparency is deliberately questioned with the designer fully aware and with the obvious reference to the ideas of the Popea’s veil covering the face of the Neron’s lover or lace lingerie (see Fig 2a and 2b). Interrupted transparency is also used to soften boundaries between the inside and outside thus the building is gradually dissolved in the surrounding landscape.
A surprisingly smooth transition from transparency to translucency comes at the end of 1980’s with the famous Très Grande Bibliothèque in Paris competition entry by Rem Koolhaas of the Office for Metropolitan Architecture (OMA). Perrault’s transparent and Koolhass’es translucent proposal clearly discriminate the separation of new trends. New postmodern transparency becomes translucency. This change in optical properties of the architectural envelope results from the intention to invite the observer of architecture to participate in the “game of guessing”. The visual information reaching the observer is only partial, leaving a great scope for individual interpretation. The connection between translucency and institutional transparency is less obvious, but still can be observed. While the optically transparent architecture is still in fashion, I perceive its blurred/translucent type to be much more honest. Blurred transmission in many cases is conditioned by the functional need of scattered illumination in the building, to name only the Bloch building, Nelson-Atkins Museum of Art in Kansas (arch. S. Holl, 2007), Kunstmuseum Dieselkraftwerk in Cottbus (arch. Anderhalten Architekten, 2007) or Kunsthaus in Bregenz (arch. P. Zumthor, 1997). The postmodern translucency introduces not only a less literal, but a more phenomenal approach to material. Paradoxically, this new contemporary blurred transparency corresponds to the condition and the social and political structure of the world much more accurately than before: the lack of rules, the vagueness of ideas, the out-of-focus human perspectives.
Illumination no longer required
Due to their high durability and resistance against climatic conditions, transparent materials are becoming a popular cladding material, not only designed to illuminate the building’s interior, but also because of their ability to change the appearance of the building. This unique feature of glazed envelopes pushed architects towards extensive use of glass, not only on light-permitting/ illuminating sections of the façade, but on the whole surface (including spandrel, slab and ceiling). In these regions, light-permeable envelopes functioned more as a cover than a fenestration. Thus, light-permeable materials are also used as elements contributing to the overall formal expression of the building by light-activating those parts of the façade that were previously neglected (Fig. 3a and 3b). Transparency thus became “a redundant feature of the material”. Light-permeable materials are “used for their chemical and climatic durability, rather than for their optical properties” (Brzezicki 2014). The image-transmitting quality of the fenestration diminishes, becomes a see-through cladding, or even a redundant feature of the light-permeable envelope.
New transparency – the conclusion
Two trends that I labeled transparent and translucent/blurred/interrupted are now coexisting. Optically transparent architecture is build/raised to convince the public of the investors’ clean intentions (regardless of their actual goals). A reflection – an immanent feature of the smooth glazed envelope – is perceived as a tool of destabilizing this picture. While transparent architecture is facing a wave of criticism, the same objections could be raised against translucent envelopes, which are designed to achieve numerous visual effects. The process of gradual erosion of transparency has led not only to the devaluation of the initial meaning of the term on the semantic level (both optical optical phenomena which scatter, hide and block the light wins over a message that directly communicates the intentions to the viewer – the clear glass and its honesty. Instead of facades, architects create multilayered envelope structures designed to obstruct the view in both directions and to allow view only to a certain predefined depth of the envelope. As a result, despite the extensive use of glass, it is the optical transparency, the visual connection and the spatial continuity, that has suffered the most.
This paper was funded by the Polish National Science Centre grant entitled: “New trends in architecture of transparent facades – formal experiments, technological innovations ”, ref. no. 2014/15/B/ST8/00191.
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