copyright: Ralph L. Knowles; 1998
RHYTHM AND RITUAL: A MOTIVE FOR DESIGN
Ralph L. Knowles, Professor Emeritus
School of Architecture, University of Southern California (USC)
Los Angeles, California
Introduction
Architects have generally ignored the temporal dimension that nature adds to our perceptions of architectural space. Of course most designers acknowledge that buildings may be transformed or deteriorate over time. But on the whole, their artistic idea of space is compositional, complete and static, the end product of many imaginative design decisions. This paper, using examples from history, from actual experience, and from research in the USC Solar Studio, argues that a spatial conception linking nature's rhythms to life's rituals can give "new life and freshness" to design.
Rhythm
Observations over time demonstrate a rhythmic measure of space.(1) For example, any architectural space that is oriented from east to west strengthens our experience of seasons (fig.1). One main wall is nearly always dark; on the other side of the space, a shadow line moves gradually up the wall then down again. To experience the whole cycle takes exactly one year. The basic movement is always the same. As the sun's path drops lower in the sky during late summer and fall, the shadow moves up. As the sun's path rises in the sky during late winter and spring, the shadow moves down. Changing the orientation of the space will evoke a different cycle and rhythm.
Any space that is oriented from north to south sharpens our experience of a day (fig.2). Both main walls are lighted, but at different hours. Every morning, light from the east will cast a shadow that moves quickly down the opposite wall and across the floor. Every afternoon, light from the west will cast a shadow that crosses the floor and climbs the opposing wall. To experience the whole cycle takes from before sunrise until after sundown.
Where east-west and north-south spaces pierce each other, we can experience both time scales (fig.3). The common volume intensifies both a seasonal and a daily cycle. It combines them, laying one over the other. The result is a crossing in space that proportions time. Its celebration has often lifted architecture out of the region of fact into the realm of art.
In great cathedrals, sunlight cycles occupy a year in the nave, a day in the transept. In a monastic church of the Middle Ages as well as a basilica of Renaissance Rome, some sort of spatial crossing proportions time. A perpetually renewed experience of wonder is intensified by the changing qualities of light, holy observances measured by variations of hue and value.
Ritual
Rituals can rise from the rhythms of a place. For example, the sun comes into our garden or through our window. We can move either toward or away from it for relief. At first our movements may only rehearse a direct search for comfort. But eventually, simple movements may be expanded in detail to express our feelings about life in the place. It is this connection between rhythm and ritual that holds enormous potential for dwellers, either in groups or privately, to act with imagination.
1. Sacred Rituals
The Middle Ages provides elaborate examples of ritual linked to place. Monks divided each day into eight ceremonial periods corresponding to the liturgical phases of monastic life. From Matins, the darkness of early morning, to Compline, late evening twilight, appropriate actions were universally prescribed for each period. The exact meaning and hour varied according to place and season. The length of the same day was not equal in northern England and southern Italy. Summer days were different in each place as were those of winter. Changing place made time different; changing time made the qualities of a place different. Changing either changed meaning.
Fig.4. 
The Cloister of Salisbury Cathedral: 1263 AD
2. Back-Porch Rituals
The connection between rhythm and ritual, while more intricate in the Medieval example, can also be found in modest circumstances. For example, my family sits down every day to eat, but instead of sitting in the same place, we sit at different tables.(2) The way this happens has been gently guided by rhythmic changes of sunlight and shadow on our back porch (fig.5).
Fig.5. 
Backporch: Seasonal shadows and table movement. (North is up.)
Almost every day we eat at least one of our meals on the back porch. The meals that we do not carry out to the porch we eat in the dining room, separated from the porch by glass doors. In and out, beginning at dawn and ending after sundown, we carry food and utensils through the doors.
Two independent sunlight cycles provide various places to sit down. In winter we are likely to eat breakfast and dinner in the dining room. But for lunch we have the choice of sitting on the sunny part of our back porch. In summer we are more likely to eat breakfast behind sun screens in the dining room. But for lunch and dinner, we have the choice of sitting on the shady part of the back porch. The texture of possibilities is rich and rewarding.
A neighbor's tree spreads over the south end of our porch. To catch the warm winter sun, we move our table northward. To sit in the cool summer shadow, we move the table southward. Back and forth, once each spring and again each fall, we carry the table across a shadow line. The moment we know it is spring is not exact. We could remember the calendar, but more often than not, on a warm and sunny morning, somebody will say, "Let's move the table." And then it is spring, no matter what happens next.
Somehow we are always astonished at the seasonal changes and the possibilities they evoke. Moving the table shifts all our connections to the house, the view and to each other. After 30 years, we are still thinking up new ways of arranging things.
Pueblos of the Southwest
The connection between rhythm and ritual is universally found in the ways people have traditionally identified with their environments; some of the most inspiring examples appear in our American southwest. Here, pressed by the harshness of a high-desert climate, early settlements recognized natural rhythms in their adaptation of location and form; the customary movements of people and their corresponding rituals confirm the impact of natural cycles.(3,4)
Fig.6. 
Longhouse Pueblo, Colorado
1. Longhouse, Mesa Verde, Colorado
The location and form of Longhouse provided ancient residents with year-round comfort (fig.6). The settlement (c.1100 A.D.) is sited in a large, south-facing cave, 500 feet across, 130 feet deep, and 200 feet high; the built structures are nestled within (fig.7).
Fig.7 
Composite Plan (North is up)
Fig.8 
Seasonal Migration of the Sun
Fig.9 
Daily Migration of the Sun
Longhouse is well adapted to both seasonal and daily solar rhythms. The brow of the cave admits warming rays of the low winter sun but shields the interior of the cave from rays of the more northern summer sun (fig.8). The seasonal adaptation at Longhouse is complemented by the pueblo's response to a daily rhythm as the sun moves from the eastern to the western sky, casting morning rays inside the west end of the cave and twilight rays inside the east end (fig.9). The thermal mass of the cave itself, as well as the structure of buildings within, helped to mitigate extreme daily variations, but a main adaptation for comfort may be best understood in the rhythms of people's lives.
It is reasonably well documented that the cave dwellers of Mesa Verde tended to migrate in and out of the cave in response to the north-south seasonal migration of the sun. The way they worked suggests that they moved deeper into the cave for shelter during summer and spread further to the south in winter, using their terraces for work and play with full exposure to the warm solar rays. This north-south migration coincided with the shadows and thus the thermal variations of exactly one year's duration. It is possible to imagine a contrapuntal migration (fig.10).
There is not much documentation of the tempo of daily life at Longhouse, but a transverse migration of a much shorter duration might very well have occurred in response to the daily, rather than the seasonal, rhythm of the sun's movement . During much of the year, morning light entered the dark cave from the east and outlined those buildings at the western end. All families in the pueblo kept turkeys, but only the turkeys first struck by the morning rays of sunlight would awake and become noisy. The turkeys roused the children who, in turn, disturbed the parents. Those first pulses of activity would then echo 500 feet against the eastern walls of the cave.
The day passed with fairly general activity distributed throughout the cave; then, as late afternoon approached, twilight first came to the western end of the cave and subdued the turkeys, then the children. Their parents could breathe those last sighs of relief while parents in the eastern end of the cave still had time to go before their day was done. As their light disappeared, the last turkeys uttered a quiet gobble and the children of the eastern cave let that day finally go.
The foregoing sequences are imaginary but not without historical foundation. The fact is that such a scene could very well have taken place. And what is more to my point, it would have occurred every day with seasonal variations suggesting a strategic rhythm both for thermal comfort and for the emergence of ritual.
Longhouse depends for its adaptation to climate on a south-facing natural formation; but other pueblos, also south-facing, are standing in the open. Some of these, like the living pueblo in Taos, New Mexico, are irregular and appear to be randomly assembled. Others, like the nearly square ruins at Aztec National Monument, are symmetrical and clearly planned. One of the most impressive of the planned type, 300 feet across its south edge and 3-5 stories high, is the semicircular-circular Pueblo Bonito.
2. Pueblo Bonito, Chaco Canyon, New Mexico
Bonito, in its original form (c.919-1080 A.D.), was built in two stages to resemble an amphitheater with a stage surrounded by curving rows of seats too big for people --- the Greek theater of Epidauros, transplanted and scaled for gods (fig.11). Even today, standing among the silent debris of Chaco Canyon, people often express deep feelings after experiencing the passage of sunlight over the powerful half forms of Bonito's ruins (fig.12).
Fig.11.
Plan of Pueblo Bonito, Chaco Canyon, NM (North is up.)
Fig.12.
Pueblo Bonito Viewed from the North
In earlier times these forms helped mitigate the extreme temperatures of summer and winter. Not only the plan but the structure of the buildings adapted to the solar dynamic. The summer sun falls primarily on horizontal surfaces comprised of timber, reeds, and clay mixed with straw with low heat-storage capacity. The winter sun falls more on vertical surfaces of stone with heat retention characteristics, allowing stored heat to re-radiate to the interior of the dwellings during cold winter days.
There is much evidence for seeing Bonito as more than shelter for the body; it was also conceived as an astronomical observatory and perhaps a temple to honor the sun.(5) Daily and seasonal rhythms were not only a condition of pueblo life, they were a cause for sacred celebration.
Some sense of this can be conveyed by simulating changes in shadow patterns within the original pueblo courtyards (fig.13 a). The result of the sun's daily passage is a shift in the patterns of dark and light in the great courtyards: west to east by day; north-south by year (fig.13 b). In the shifting spot-lighted areas, it is easy to imagine ritual activities migrating, taking place at different locations in the courts at different times of the day and year (fig.13 c). Such rituals occur today on the terraces and in the courtyards of modern pueblos.(6)
Such observations, both on site and in the laboratory, are compelling when contrasted with modern architecture's avoidance of nature. Our machines automatically reduce natural variation to a narrow range of light, heat, and humidity. In the process, we have lost a sense of harmony that derives from feeling the complex rhythms of nature. And we have lost more.
We have lost an essential challenge to our imaginations. When we flatten and simplify nature, we lessen the need for many customarily repeated acts. Take the most banal example: putting on one's sweater or taking it off. The sweater itself --- its age, color, texture --- asserts our personality. So does the way we carry it on our bodies --- tightly fitting or loose and baggy. The sweater and the wearing of the sweater can become a system of rites, a ritual observance of ourselves-and-our-environment.
A Motive for Design
The USC Solar Studio has, over the past twenty years, been dedicated to exploring solar policy and design. Our investigations in Los Angeles have centered on the idea that solar-access zoning, by means of the solar envelope, will not overly constrain either development or design in the city.(7) But lately, working within a presumed context of solar-envelope zoning, research has focused on the notion that sunlight adds a dimension of time to our perceptions of architectural space. Supported by continuing attention to indigenous settlements around the world, there has emerged a corresponding investigation of the ritual dimensions of architecture.
A central theme of the Studio is that space is generated by flux itself. The notion of completion is thus antithetical to all design activities. Whether accomplished by heliodon, computer, or outside under the open sky, any design execution is calculated to be experienced as a measure of time, the whole scheme as a consequence of daily and seasonal rhythms of sunlight.
This is the case with all work in the Solar Studio, but the proposition has reached its greatest amplification and expression in a recent library project. The actual program of required spaces was obtained from the Los Angeles library planners, but the spirit of the program was taken more from a comment by Louis Kahn about his own design for the Exeter Library: "You get a book and move toward the light." He thus implies a conception of architectural space that is both rhythmic and ceremonial.
1. The Mama Plane
The design link between rhythm and ritual is introduced in the library project by asking students to imagine a wall with a gateway through it. If the wall faces east and west, it will accentuate a daily rhythm; shadows will appear first on the west and then on the east, regardless of season. But if the wall faces north and south, it will emphasize a seasonal rhythm; the shadow extends much farther northward in winter than in summer regardless of the time of day. Finally, if the wall faces diagonally to the cardinal points, the accents will be complex and contrapuntal. In each case, a person seeking either sunlight or shadow must pass through the gateway at regular intervals.
A corresponding wall can be conceived that reaches to the upper boundaries of the solar envelope and that, standing alone, can fill the envelope with shadows over time and seasons. The wall in sunlight can act as a generator, an allusion to invisible form. When the form is brought into concrete existence, sunlight replays a series of connections in space and time. The generating wall has been dubbed the mama plane .(8) Its applications in the Solar Studio have sometimes been quite direct.
2. A Light-Penetrating Strategy
One design for a library develops a literal interpretation of the wall and gateway (fig.13 ). Beginning with the mama plane, an opening through it allows sunshine to penetrate to a second plane where the lighted area is removed. After a prescribed interval of time, sunshine passes through both openings to a third plane where the lighted area is again removed. This process is continued throughout the course of a simulated day, interval by interval, until the final design embraces the entire set of planes. The openings will not only generate a system of transverse spaces but, on all future days, will act in sunlight to recite the original sequence of daily connections with seasonal variations.
Fig.14.
Library Viewed from West. Designer: Anthony Reiter.
3. A Shadow-Casting Strategy
A second design for a library uses shadows cast from edges of the mama plane to create both the building and a garden. The mama plane, with a diagonal orientation to the cardinal points, has been given thickness by the designer and serves as book storage, service, and circulation. To the south-west of the plane, morning shadows moving across the ground have been used at prescribed intervals to outline the terraces of a garden with parking below (fig.15). To the north-east, afternoon shadows are used to define the shapes of floor plates: one set is generated on a winter day, alternate plates on a summer day (fig.16). And as with the previous design, the creative process will be recited over time.
Fig.15.
Library Viewed from Southwest. Designer: Gustavo Koo.
4. Technique of Study
Models have been heavily used as a means of study in the Solar Studio. Initial investigations rely on small-scale models, only a few inches across, analyzed on the heliodon; but as the work progresses, the scale of study increases step-by step, finally to include models two-three feet high.
Large models have proved especially useful for analyzing rhythmic transformations of interior space. Computers have recently added a powerful tool to augment such large-scale studies. Still, the physical model, either on the heliodon, outside under the sun, or under some controlled and movable lighting in the studio, continues to provide a powerful study method offering tactile as well as visual cues to design. Two library studies illustrate how designers use models to accent different measures of space.
One large-scale investigation gives emphasis to a daily rhythm (fig. 17). The designer includes a long, high space with broad E-W exposures. Morning light enters from the east, casting shadows to the opposite wall. Midday light enters from directly above through adjustable skylights, casting shadows directly onto the floor. Afternoon light, entering from the west, is controlled to avoid direct sunlight on the opposite wall where the designer has placed book storage. The powerful alignment of the space assures that daily experiences will be only marginally altered by seasons. Designer: Jacky Yung.
A second investigation accentuates a seasonal rhythm (fig. 18). The designer here responds to a major N-S exposure of the site by employing tinted planes through which sunlight passes in various seasonal combinations. The planes admit blue light in summer, amber light in spring and fall, rose light in winter. The planes remain fixed while the sun's passage transforms color and space. Though not perhaps appropriate for a library, the idea otherwise has extensive architectural possibilities. Designer: Shaw Bing Chen.
When viewed at an instant, the designers' models reveal a compositional richness; but with observations over time, the continuity and rhythm of events can be imagined. As the day passes, impressions of the whole swing to and fro --- spaces alternate from dark to light, from warm to cool. If the designer's intentions were carried through into actual construction, the pulse of human activity within the spaces would be reinforced by these light and heat cycles.
The intent of this work is not to suggest that we would somehow be ennobled by a wholesale return to more primitive levels of adaptation. There is real suffering in being too hot or cold, or in having to migrate long distances to follow the seasons.
The problem is more involved than that. The permanent places where we spend time do need to reduce stress on our minds and bodies. But there is a real question of means: Do they have to hide from us every small variation that might repeatedly summon us to action?
My point is that something reassuring comes from the consonance of our actions with the motions of nature. The something may remain forever unknown. Perhaps it is nothing more than the cyclic re-proportioning of our bodily fluids. But more likely it is a reaffirmation of our own existence --- a continuously repeating call for recreation. Our universal need for this call should not be underestimated nor its basis be trivialized by design.
Conclusions
The intent of the USC Solar Studio is to reclaim creative possibilities for people by linking rhythm and ritual in the buildings and spaces we occupy. Close analysis of the way native people have traditionally identified with their environments has suggested the value of such a linkage for modern design. This is not to say that we should all return to primitive shelters. The places we now occupy do need to reduce stress on our minds and bodies, but there is a real question of means. By depending on machines to provide bodily comfort, architects have hidden from us every small temporal variation that might repeatedly summon us to action. By examining the influence of natural rhythms on form and space, the USC Solar Studio aims to reintroduce rhythm as a mysterious fact of aesthetic experience.
Footnotes
1. Ralph Knowles, "For Those Who Spend Time in a Place." PLACES Volume 8 Number 2 (Fall 1992): 42
2. -----: 43
3. -----, Energy and Form (Cambridge, Massachusetts and London, England: MIT Press, 1974), 17-46
4. -----, Sun Rhythm Form (Cambridge, Massachusetts and London England: MIT Press, 1981), 11-15
5. Anthony F. Aveni, ed. Archaeoastronomy in Pre-Columbian America (Austin, Texas and London, England: University of Texas Press, 1975)
6. Vincent J. Scully, Mountain, Village, Dance (New York: Viking Press, 1975)
7. Additional tests of the solar envelope were undertaken by the author in Bratislava, Slovakia under a 1993 Fulbright Grant. The work was carried out with Dr. Julian Keppl and architecture students of the Slovak Technical University. Generally, the resulting buildings were one story shorter and more complex than those in Los Angeles due mainly to a more northerly latitude and the medieval street pattern of the study sites.
8. Kim Coleman and Ralph Knowles, "A Case Study in Design Studio Teaching: The Parallel Studio," The Design Studio in the 21st Century: Proceedings of the 1992 ACSA West Regional Meeting, (College of Architecture and Environmental Design, California Polytechnic State University, San Luis Obispo, California, October 1992): 4