[1] Do architects inhabit windows differently?

There is an indefinable moment when students become architects: when they look at a window in order to look inside. Into the window, if metaphysics allows it, but also into the history of architecture, as an object of study. The window is at once essential and banal, like a cane to someone with a limp. Designing this cane is the daily task of the architect. Of course, students are never openly told this (it would come as quite a shock). It is a secret administered in homeopathic doses, becoming ingrained gradually and without warning; it is never even questioned. When the realisation hits, windows are already a part of us; they are what we do.

As a professor of history of architecture, I talk about windows all the time, mostly without realising it; they are the air breathed by architects, the air which finds it way in through slides.

When visiting buildings we cannot enter, as so often happens to robbers and detectives, windows assume enormous significance: they are our brief and fleeting gateway to an imagined interior. The shadows they cast are almost malevolent – filters which reveal little. This is the moment the window takes on a malice not available to the door. After all, a door either opens, or does not. Windows take their time, pretending for a while, promising what they cannot deliver.

When designing windows, the architect returns to the fine arts, like James Stewart to the voyeurism of Rear Window

[2] When Frank Lloyd Wright began to abandon “sash windows” in favour of “casement windows” in the Winslow House (1893), seeking to create a gradually glazed continuous plane, the game began to change. In the Chicago School, the window had already undergone designs likening it to a “glass façade”, as in the Reliance Building (Burnham and Root, 1895). Wright transforms the window into a complex architectural activity, which can move up or down in the context of the house, extend as far as the ceiling, shape space, join or leave the perimeter, have thickness, be an object rather than simply a device. There is a drama in Wright’s windows which seems to reflect the drama of his own life. In the Robie House (1909), windows become the house’s negative image, with a structurally architectural function. They are not sub-products adorning walls, symmetrical or replaceable; they determine, as much as or more than the wall, the architecture of the house.

There is a famous discussion between Le Corbusier and Auguste Perret (with whom he worked) on the virtues of the horizontal window (fenêtre en longueur) as compared to the vertical one. Perret maintained that the vertical window expressed the human body, framing it in an anthropomorphic, primordial relationship with the outside world. He equated Le Corbusier’s horizontal window with visual excitation and a panoramic view, which he detested. Le Corbusier’s figurative man stood with open arms, surveying the world over 180 degrees. Nothing could stop him.

However, the argument was won by Mies van der Rohe, who abandoned the idea of the window as an opening, transforming it instead into a plane. Applying the principles of Dutch neoplasticism, Mies invented a window which was no longer a window: the “glass curtain wall” was about to emerge as the solution best suited to the idea of the skyscraper as an abstract, monolithic, mathematical structure; America is grateful.

[3] The glass does not make the window; what makes the window is the frame. Glass produces reflections and casts shadows – it is not transparent. The frame is gone. What, then, remains in the “glass curtain wall”? An enigmatic surface, possessive, self-referential.

The window has been an interface between technology and culture ever since man thought to pull a stone out of a wall to make a hole and begin the day, as Louis Kahn would say. The “glass curtain wall” embodies a triumph of technology over culture in that it does not reflect a measure or deliberation of an anthropomorphic nature, a man standing with open arms and a fixed or panoramic gaze.

The window’s reinvented design – or its disappearance – define a number of key moments in 20th century architecture. In the extreme case of an architecture seeking to become free of itself – in order to be a machine, a piece of furniture, a device – the first casualty must be the window. Vertical or horizontal, the window “demands” the silhouette of a man or woman, immediately fixing ancestral measurements. It creates a theatre, it implies a stage. The window signifies a story which has already taken place or has yet to be told.

The “glass curtain wall” aims to bring about the end of suspense, the end of narrative, the end of secrets. It would later be necessary to install curtains in the Farnsworth House (Mies van der Rohe, 1950) in order for the theatre to recommence. Curtains make the window, as we learn here. But do they also have the capacity to redeem a house without windows? How often, in hotels, curtains suggest windows which fail to materialise… Without curtains we would be in a nameless hole; windows are dispensable…

The “glass curtain wall” is an automation; a conquest of architect-builders, entrepreneurs of a united world. The work of Dan Graham and Eduardo Souto de Moura can be interpreted as a perpetuation of this event for art and architecture. Dan Graham’s pavilions employ the “glass façade” for a critical performance in which the mirror accentuates the labyrinthine dimension like a transparency taken to to the extreme; in the architecture of Eduardo Souto de Moura, the “glass façade” is placed in “dialogue” with vernacular elements in a collage in which the spoils of the 20th century – modern, primitivistic, ruralist, hyper-urbanised – collide.

[4] Forgetting for a moment the grand question of curtains, what windows – or non-windows – does the future hold in store for us?

Perhaps a biomorphic window which adapts to our body – neither horizontal nor vertical, neither façade nor wall. When that time comes, the window will be a projection of every one of us; and just one of many screens we use to look outside. (Inside?)

Alongside these neo-windows, more conventional ones will also continue to exist: with shutters, blinds, hinged, louvre, tilting, mysterious. Our search for intelligent windows began when we were still living in caves; windows accompany the slow/fast progress of mankind, like a cane for those who wish to see, stoically immobile, in the lounge or bedroom.

Windows in the ceiling to admit “zenith light” are known as skylights, but we have yet to find a name for those in the floor which allow us to contemplate Roman ruins. Mirrored glass creates a specular window which projects the movement of the clouds onto tables and office staplers.

Every window aspires to be a mirror, one day. The mirror is a window which has become emancipated, which has acquired a personality. It shows only what is already known.

When every window is a mirror, architects will no longer be needed.