Light-space is an imaginary space which is created when a portion of space is well lit while the rest is left in semi- or total darkness . The limits are imaginary but perfectly perceptible. If the observer is situated outside the lit area, he sees it as ‘a transparent box within a large box’. The small illuminated box concentrates his attention. If he is within the small illuminated box, the space in the semi-darkness appears of indeterminate size to the point of ceasing to exist.
The light-space is very useful in architectural design. It makes it possible to present scenes as in the theatre, the circus, the museum, a shop window at night, in the open air, etc. It also enables the person who is in the illuminated area to isolate himself and concentrate better, just as when, with our individual work- or reading-lamps, we are in a large office or at home and the rest of the space gradually vanishes.
Since the coming of electric light, such spaces can be created and transformed instantaneously and at little expense if compared with mechanical alterations of spatial lay-outs. In the daytime, a shaft of sunlight through an opening into a relatively dark room can have a similar effect, but now the ‘little box’ moves, following the sun’s course. Its effect is more often a marvellous accident than a calculated intention.
光作为物体 Light as an object
Light as an object, the single window, the isolated stained glass window, an object or a person spotlit in a dark space, a candle in a room, establish a relationship of dependence between source and space similar to that of figure and ground. When looked at directly, the source fascinates and dazzles at the same time, on condition, however, that the size of this source is relatively small in relation to the spatial envelope. When one turns one’s back on the source, spatial perception is completely altered, because the walls, the floor and the ceiling in turn become weak light sources whose surface is immense and enveloping.
In terms of design, it can happen that we try to work with a unique, concentrated source for practical or symbolic reasons, at the same time wishing, for one reason or another, to avoid this alternation of glare and uniform lighting. In this case the source must be placed well above eye level (e.g. the Pantheon) or even concealed (indirect side lighting). It is not by chance that glare is used for intimidation and torture. Each architectural project must be reexamined from this point of view before building, in order to avoid this kind of aggression. Too often glare makes the most important and highly valued things disappear.
一系列光源 Light from a series of objects
Light from a series of objects, series of windows, spotlights, candles, tends to establish balance and a possibility of inversion between the figure character of luminous objects and the background character of the spatial envelope which they illuminate.
A regular series of windows, or wall lights, or even a strip window, make an active contribution to the delineation of spatial limits. A larger or smaller window on the axis, or a series of lights suspended on the centre line of the room, help to clarify the spatial geometry. A freer arrangement of the light sources requires understanding of the principles of balance.
洗墙光 Light from surfaces
Light from surfaces; the walls ceilings and floors may be lit by invisible slots. Spatial limits thus become light sources with a noticeable gradation from light to darkness.
One does not observe the same phenomenon with the surface of the illuminated ceiling in a department store or an office, because the absence of gradation eliminates the quality of throwing figures into relief. The dominant presence of the ceiling, due to its glare and to the absence of contrast, is tiring. Lighting engineers resort to additional light sources to restore necessary contrast. It is only during recent years that a technique has been found to ‘put these ceilings back in their place’, thanks to ceiling lighting with mirrored reflectors.
The corollary of the luminous ceiling is, in daytime, the skylight which, if one looks carefully, is practically never used for places where people stay or work for a long time, with the exception of factories where functional requirements make other solutions difficult.
The large glazed wall, in turn plays down contrast but, by being vertical, it does not do away with it altogether. Its role as a spatial extension very often takes precedence over its purpose for illumination. According to its size and orientation, it can create problems by an excess of light and heat.
These brief considerations on light and space are both important and incomplete. Sometimes it is possible to break these elementary rules in order to obtain the most appropriate atmosphere for the purpose of the building. In a place of worship, lighting from behind the altar can invite meditation. What is important is that the study of light be considered as an essential part of the different stages of the design and its execution. Large-scale models are very useful. Photographs are deceptive because the sensitivity of film is not comparable to our subjective perception.
A skylight placed in the middle of a low room cannot, in any way, despite appearances, resemble the sun, because its proximity prevents it being considered as a source producing parallel rays. The atmosphere of the room tends to become ‘pale’, dusty, sometimes even sad or, more rarely, solemn. When this same opening has a direct relationship to the structure or to a wall, and the light can descend by means of a vertical receptor, a direct link is reestablished with the space, and contrasts are re-introduced.
Shadow, like light, used consciously as a line, can be used to delineate, even to emphasize the forms and edges of bodies and space. The shadow cast by the outline of a cornice emphasizes the upper termination of a façade. Window frames produce an elegant line when positioned flush with the façade whereas the shadow line from a deep recess emphasizes the apparent weight and thickness of the structure. The recessed joint between a timber frame and the wall defines the articulation.
In conclusion, let us remember that, on a practical rather than aesthetic level, light and shade regulate the use of a space more often than do its size and form. The presence or absence of contrast, as well as the definition of space by the quantity and quality of illumination of the space, appreciably influence its potential and the wellbeing of its occupants.