Howard Davis/The Typological Approach
Architectural Facts in Search of a Language
Form Language Symposium - Dresden, June 2001
--Continued--
The Typological Approach
First, the typological approach.
From one point of view, the typological approach is the simplest and most straightforward way to describe this house. In fact, I have already told you most of the terms used: courtyard, arcade, "skifa" which is the passage, entrance, rooms. In describing this house, the typological approach would likely employ a series of simple diagrams that relate this specific example to an ideal archetype. These diagrams show not only the existence of various parts that can be named, but also their relationship to each other. Graphic representation is essential to this approach, as it is to the others.
One reason this approach is so useful has to do just with this simplicity, with the ability for abstraction and the reduction of complex configurations down to simple diagrams that may have abstract meaning. It is these kinds of diagrams that form the basis for the "parti" which we ask students to invent or discover in the course of design. And the parti may connect to certain aspects of meaning. The courtyard, for example, is symbolic of the house as a whole – in fact the words for courtyard and for house are the same in Arabic. And one of the unifying features of North African Islamic architecture is of course that the courtyard building is ubiquitous in the city, serving many different functional types, and this helps to connect the house with the mosque, within a higher understanding that sees the courtyard as an image of paradise.
This approach has a direct and obvious connection to the most common ways of representing a building – namely, the orthographic projections. But as I hope will become clear, this is also its weakness. The orthographic projections only hint at such things as the typical paths of movement through a building, or the differences between two rooms in their feelings of focus and spatial intensity, or some of the connections that may exist between architectural form and human use.
Hillier´s Approach
Let me next describe Hillier’s approach, which emphasizes a different kind of abstraction, that emphasizes a property which Hillier calls "depth." The approach requires that plans be transformed into a kind of diagram that treats all convex spaces as points, or nodes, and doors or door openings between these spaces as lines. What this diagram does is not only allow an immediate picture of relationships among spaces, but allows an understanding of the depth, or number of spatial steps, from one space to another. It is very easy to see, for example, something which is not as immediately apparent from the plan or the typological diagrams – that the rooms that are deepest from the entrance are the ones marked green. And any room may be the root, to determine the depth of all other rooms from it.
The essence of the approach is shown in Hillier’s own analysis of these four hypothetical plans. From one formal point of view the plans are extremely similar. But they are experientially very different. Plan (a) is highly centralized; plan (b) has a kind of enfilade of rooms around the edge, plans (c) and (d) are different variations. The adjacency graphs show widely different topologies among the different examples. One interesting thing here is that the space which appears to be most central, has a very different position relative to the outside in each of the four examples.
Now you may say that this does not really have to do with architecture, and just has to do with where doors are placed. But what I am talking about is the basic topology of configurations, which is connected to the social origins of building type. The power of this approach is perhaps best seen in more difficult cases. For example Hillier has analyzed much more complex vernacular situations to show how power relationships are embodied in the topology of configurations. In this African compound, for instance, the chief’s hut is located in the place that is topologically deepest into the configuration – even though it is physically located near the outer wall.
Perhaps even more interestingly, Thomas Markus has used this approach to study how institutional buildings changed during the eighteenth and nineteenth centuries, to demonstrate how changes in social ideology were reflected in corresponding changes in building plans.
One example shows a school built in London around 1874. This school is an educational hybrid, that combines various features of earlier schools, in which groups of pupils were together in the same large room, with schools that came later, with each group of pupils having its own classroom. Boys and girls had their own entrances, right and left respectively. The plan is quite symmetrical. But the adjacency diagram is remarkable in two ways. One is the very clear gender division, between boys and girls – notice in the plan how the boys’ staircase stops at the first floor – this is node 13 in the adjacency graph. The other is how the groups considered the most vulnerable are deepest into the plan. These are the babies – nodes 5 and 10 – which are very deep into the plan, even though on the ground floor; and the girls, which are very deep into the plan, on the second floor.
Another example is of a workhouse in London built in 1725. The designers of this building intended it to be a model for similar buildings to be erected all over Britain. This is only the ground floor of the building which include kitchen, dining rooms, schoolrooms, work yards and privies. The plan is symmetrical around two axes of symmetry. In his analysis, Markus points out that the rooms which are deepest into the plan and at the end of tree-like structures, are the workrooms and privies – these are the spaces and functions which most needed to be controlled. And the central spaces, which are the spaces from which centralized control was apparently exercised, lie on rings making them accessible to many other spaces of the building.
In contemporary practice, Hillier’s technique is used for analysis of large buildings during the design phase, and it is also used at an urban scale to test different urban design schemes against desired pedestrian activity. One very recent, high-profile use of the technique was in the urban design studies at the time of building the Tate Modern in London, and the pedestrian bridge across the Thames that leads to St. Paul’s.
A major advantage of this technique has to do with the ability to be mathematically precise about spatial relationships, and such precision is necessary when analyzing large configurations . This lends itself to computer analysis of certain aspects of complex projects during the design phase. But this mathematical precision is balanced by a loss of qualitative understanding – a large room and a small room, a light room and a dark room, are all the same in this technique, all other things being equal. But because of its ability to analyze extremely complex configurations, the technique has had success in predicting human movement in cities and such buildings as art museums and hospitals, and in helping to develop an understanding of power relationships in buildings.
I would also point out, before going on, that for the simple courtyard house, it is very easy to put the two diagrams side by side – the one representing the compositional approach and the one representing the space syntax approach – and clearly see their relationship. But as we have already seen, this is not true for complex buildings.
Alexander: Patterns
Let me go on now to Alexander. I’d like to begin with his older formulation, because that is more familiar to many people. The pattern language approach grew out of observations that are essentially functional ones. As such, it was originally a particularly modernist point of view. These functional observations are concerned with recurring human or environmental issues within the environment, and what physical configuration might resolve those issues so that conflict is minimized.
An example of such a pattern is ENTRANCE TRANSITION, which essentially says that the difference between the psychological state one is in on the street and the psychological state one is in inside a house has a corresponding spatial form, in the ENTRANCE TRANSITION, which provides for a change of physical characteristics along a path between street and house. Now there are undoubtedly some healthy situations in which this pattern does not exist or is very weak, and where it does exist it clearly takes on a different form from culture to culture. But in very many situations it does exist, and is even useful because it brings to light what many see as an essential characteristic of houses.
Another example of a pattern is INTIMACY GRADIENT, which says simply that as one goes deeper into a house, one finds rooms that provide more and more privacy and intimacy, and less publicness. Again this has different manifestations from culture to culture; in many Latin American situations the formal living room, where guests are received, is located quite close to the front door; in other cultures such a room is deeper into the house. What is much more rare are houses where such an intimacy gradient does not exist at all, where all rooms are at the same depth from the outside. And for building analysis, the point is not necessarily that this pattern exists or exists in a particular form, but that it is necessary to take this issue into account.
There is a strong relationship, again, between Alexander’s formulation of patterns and those of typology and space syntax. In typological terms the ENTRANCE TRANSITION may sometimes be given the name of a thing: the skifa in the middle eastern house, the fauces in the Roman house, the path-plus-front porch in the small town American house, the outside step-plus-vestibule in the London house. And in Hillier’s point of view, the entrance transition will be represented by one or more nodes connected by lines, the assembly of which gives all of the rooms of the house greater depth relative to the street.
In the case of the Tunisian house, the entrance transition is not simply the skifa; it is the experiential change between street and courtyard that is both facilitated and mitigated by the skifa. Another way of saying this is that if we were to take the skifa alone and build it in the middle of the desert, it would not be an entrance transition, it would just be a set of walls and roof.
Now, looking at diagrams of these three approaches side by side, I want to claim that although these are different representations of the same thing, the emphasis of each one is different enough from the others so that more insight is gained from looking at the three of them than only at one. I will take this up more later.
Alexander: Centers
Alexander’s current work shifts the focus from patterns to what he calls "centers." The emphasis is subtly changed from the relationship between things being at the center of our attention, to the idea of a physical entity itself being the focus, but gaining its intensity and meaning from its relationship with other things. In this respect there start to be some connections to the typological approach. In the courtyard house, the courtyard is the principal center. It is the most important space, and it is the space that will have the most investment put into it in terms of architectural elaboration and ornament. But it does not exist only by itself, but it gains its character and particularly its intensity from the other centers which are around it. Each of those centers, of course, does the same thing, so what we have in a successful building or city is a strongly interacting field of centers, in which the success of any one depends on the success of all the others.
I would like to illustrate this concept further by looking at this carpet, and pointing out that the unity of the composition which exists here comes about because the individual centers have a strong mutual dependence on each other. This is more than simply a figure-ground phenomenon, but has to do also with the strong identity of figures and the fact that such identity exists at different scales.
The idea of centers can help to illustrate variations within typologies as well. The simple courtyard house is very closely related to others built at the same time. These 27 houses are in Tunis, and all built around the same century. They are arranged roughly in order of size, and probably economic status of their owners. They all share the idea of a central courtyard, rooms around the courtyard, and indirect entrance or entrances from the street. What is happening, as we go from large to small, may be characterized as an intensification of centers. Axes of symmetry that are less important in smaller houses become more important in larger houses, and that importance is reinforced by additional centers, in the form of arcades and rooms which support them. And those rooms, in even bigger houses, are reinforced by rooms which support them and give them even greater intensity.
So in this analytical approach, like in the typological approach, there are entities that can be named. But unlike the typological approach, in which the description of a building is to some extent a description of entities and their relationships, this formulation emphasizes that the life of entities comes, at least to some extent, from the entities around them, and all the entities that are a part of the same composition.
