Nothing there: the art and science of transparency is evolving from Modernism's preoccupation with light and lightness to intelligent skins.

In Jewish legend, King Solomon is reputed to have built a glass palace in order to reveal whether the visiting Queen of Sheba was a real woman, or, as suspected, a genie. When the Queen, not familiar with the illusory effects of glass, entered Solomon's palace, she believed him to be sitting in the middle of water. Hitching up her skirts to keep them dry, she inadvertently exposed her hairy legs, thus revealing the telltale mark of a genie. (1) This legend, in which the material properties of glass architecture conspire to divulge Sheba's true supernatural nature, can be construed as an (albeit whimsical) example of both literal and phenomenal transparency. The relationship between these dual aspects was first explored by Colin Rowe and Robert Slutzky in the mid '50s as a riposte to what they saw as a limited awareness of transparency in architectural circles. According to Rowe and Slutzky, the obsessive use of transparent materials (literal) had led to the neglect of perceptual transparency (phenomenal), the quality that allows the mind to discern underlying intellectual, organizational and spatial concepts. (2)

In the modern era, the notion of transparency has exerted a particularly seductive and tenacious hold on architectural imagination. It began with the early Modernists who evangelistically affirmed a new set of values for modern buildings--transparency and dematerialization--achieved through material lightness and spatial interpenetration. But it also caught the emerging mood of scientific rationalism. As Nigel Whiteley notes, 'Transparency was a symbol of a scientific age that demanded nothing less than clarity, precision, openness and honesty'. (3) Both literally and phenomenally, transparency provided a decisive break from the clutter and ambiguity of previous eras. In literal terms, transparency found its most radical expression in the invention of a sheer glass skin, which came to supersede conventional glazed openings in a skeletal structure. Gropius' Fagus Factory of 1911 was one of the first examples of a glass facade supported by a thin steel framework, and Bruno Taut's polygonal Glashaus Pavilion for the 1914 Werkbund Exhibition in Cologne was made entirely from glass, dramatically celebrating its ephemeral, crystalline properties. Both are familiar icons of early glass technology and set the pioneering tone for future developments.

The famous Tugendhat House of 1930 by Mies van der Rohe embodied some of the more excessive aspects of the new quest for minimal enclosure and free-flowing space. For monumental villa in the Czech town of Brno. Mies employed huge sheets of plate glass with as little interruption by the frame as possible. He then went one step further, installing a mechanism by which the windows could be lowered electrically and removed completely. The cost was phenomenal (equivalent to eight luxury apartments), and perhaps this is one of the reasons why Mies never repeated the experiment. As Terence Riley observes, 'What Mies really wanted, which doubled the luxury, was nothing there. Glass was a surrogate for nothingness. If the glass isn't there, there is only the frame, the structure as definer. Mies was trying to establish a continuum of space between interior and exterior that confounds the presence of glass. Real space is thus inside and out: the ultimate sense of transparency'. (4)

Visions, virtues and vices

From medieval cathedrals, in which the word of God was metaphysically illuminated and disseminated through stained glass, to the glass train sheds and gallerias of the industrious Victorian era, the quest for literal transparency has been crucially underscored by the technical development of glass. Writing in 1914, German visionary writer Paul Scheerbart described his fantasy of a world revitalized by glass architecture '... which lets in the light of the sun, the moon and the stars, not merely through windows, but through every possible wall, which will be made entirely of glass'. In his classic text Glasarchitektur, Scheerbart's vivid speculations proved an inspiration to the emerging Modernists at a time when the potential of glass technology was gradually becoming apparent. Nearly a century on, Scheerbart's vision of an architecture made entirely of glass has become a reality. Glass is now nonchalantly employed not only as cladding, but also, rather more perversely, as structural columns and beams. However, as technology continues to evolve, notions of literal and phenomenal transparency have also shifted and become more complex. The glass curtain wall has become a stale emblem of global corporate architecture, and transparency is no longer fetishized with the utopian zeal that defined early Modernism. 'This is because', suggests Nigel Whiteley, 'in the twenty-first century, transparency is a complex concept involving honesty, democracy, accountability, legitimacy, surveillance, spectacle, marketing and virtuality. The Modernists' optimism that it simply reveals truths and honesty was simplistic and flawed. Today we are ambivalent about the different guises of transparency, just as we are frequently ambivalent about notions of public and private, about scrutiny and spectacle, and privacy. For the architect, the virtues and vices of transparency are no longer clear. (5)

Transparency is not, and never has been, a simple or static condition. Being a highly reflective surface, glass can generate a myriad of distorting and deceptive effects (as the Queen of Sheba discovered). 'Glass mediates to reveal what is real or apparent, what is mirrored from nearby, what is virtual or elsewhere, and even what is concealed or latent. Glass is a manifold veil, boundary and filter, barrier and threshold, concealing and revealing', notes Peter McCleary. (6)

Beyond the theories of perception are more profound issues. How, for instance, can transparent membranes be reconciled with the increasingly pressing issue of environmentally responsive design, a question that has dogged Modernism from Corb's half-baked attempts at a mur neutralisant, to the Case Study Houses. Despite being a highly progressive manifestation of transparency, the Eames House had predictable problems with environmental regulation; when asked by a visiting architect how it was heated, Charles pointed to the sweater he was wearing. Today, a building's facade can account for between 15 and 40 per cent of its total budget and may be a significant contributor to the cost of up to 40 per cent more, through its impact on the cost of building services. (7) The development of so-called intelligent skins that can efficiently regulate the internal environment in terms of heat, light, sound, ventilation and air quality represents the next great technical and architectural challenge. The static, impermeable transparent envelope now has the potential to become a flexible, adaptive, dynamic membrane operating as part of a holistic building system.

This issue considers many contemporary interpretations of transparency, from Hascher Jehle's Art Cube in Stuttgart (p52), which incorporates a sophisticated system of environmental regulation typical of German commitment to green values, to SOM's creation of a crystalline landscape animated by coloured light for a school in rural Connecticut (p66). In New York, Yoshio Taniguchi's eagerly anticipated new extension to the Museum of Modern Art (p40) is conceived as an exquisitely neutral armature for art, but in its sheet formal and material finesse, it also has a curious mirage-like quality. In some ways, despite the imposing scale and lavish expense, the result is a kind of stealth architecture--discreet, minimal and transparent, that merges into midtown Manhattan. Like Mies' Tugendhat House, when you look hard, there seems, paradoxically, to be almost nothing there.

1 'The Interpretation of the Glass Dream: Expressionist Architecture and the History of the Crystal Metaphor', Rosemary Haag Bletter, from The Light Construction Reader, ed Todd Gannon, New York, Monacelli, 2002, p313.

2 'Transparency: Literal and Phenomenal', described by Rowe as a 'dangerous and explosive little essay', was first written in 1955-56; it was subsequently published in 1963 and was widely read in the 1960s, influencing several generations of American architects.

3 'Intensity of Scrutiny and a Good Eyeful: Architecture and Transparency', Nigel Whiteley, Journal of Architectural Education, vol 56, no 4, May 2003, p8.

4 'Reflections on Transparency: An Interview with Terence Riley', Cynthia Davidson, from The Light Construction Reader, ed Todd Gannon, New York, Monacelli, 2002, p47.

5 Whiteley, ibid, p16.

6 'Thoughts on an Architecture of Glass', Peter McCleary, A+U, no 352, p6.

7 Intelligent, Skins, Michael Wigginton and Jude Harris, Oxford, Architectural Press, 2002, p3.