Keywords: Beijing, China, Courtyards, Solar access, Orientation,

Housing, Tsinghua University

ABSTRACT

The city of Beijing, China has a extensive history of climatically responsive courtyard housing. During the summer of 1985 the authors had the opportunity to observe many of the influences shaping the current forms of housing in Beijing.

The courtyard form in Beijing developed based on cosmological principles which simultaneously provided solar access and privacy. In many ways the vernacular courtyard house was a microcosm of pre-revolutionary Chinese society. The traditional courtyard houses maintained solar access and orientation as a primary design objective. Today, these qualities continue to be highly valued.

The modern Beijing apartment building is a six-story walk-up which achieves much higher densities than the courtyard house while maintaining solar access and orientation for each unit. However, the contemporary apartment building type is perhaps not the best solution for Beijing. This paper compares the habitable qualities of the traditional and contemporary housing typologies and reviews concerns relevant to the design of low energy housing. A solar high density/low rise courtyard housing prototype developed at Tsinghua University is used as an example to illustrate these concerns.

Beijing dates from 1300 a.d. and was designed as a walled city layed out on a grided street pattern.

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Title: Plan of Beijing 

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This city plan (repeated in the seven imperial cities in Chinese history) is a cardinal grid. The cardinal grid was indicated by the cosmic Chinese description of the world with polar north defined as the center of the world. From this central point the divine emperor faced south at all times. This cosmic symbolism required that the emperor's dwellings and halls always faced south. In this way the Imperial cities, such as the most recent of the Imperial cities, the Forbidden City in Beijing, (circa. 14600) were built.

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Title: Plan of the Forbidden City 

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Local family courtyard houses or estates in Beijing were modeled after the Forbidden City. With the same priority for solar access, the most prestigious family member's dwelling unit within the courtyard house complex faced south.

The cardinal grid plan of Beijing which was proscribed by religion and culture was also a useful means to afford orderly and efficient access to the southern exposure. The architecture of the buildings followed with a climatic response further maximizing the southern exposure.

2.0 The Traditional Courtyard House

2.1 Description

Each family home or compound formed a rectangular courtyard house. The external façade of the "house" was only a low wall (one story high) to the street. The walls of many courtyard houses from the blocks of the "walled" city known as "jia-fang". 

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Title: Blocks of Courtyard Houses 

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Today, the pedestrian experience of the older sections of Beijing offers a view of only an orderly network of grey walls. The inner beauty of the courtyard buildings and the family life is sheltered behind these walls. This design is not only an architectural response to climate but is indicative of a centralized, inward looking culture as well. Like the Forbidden City was for the emperor, Courtyard houses were small protected domains for the upper classes.

Within the courtyard house complex is a progressive series of south facing buildings.

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Title: Floor and Roof Plan of a Typical Courtyard House 

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Title: View of Courtyard House 

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Unlike the external grey walls which line the narrow city streets the buildings within the courtyard were often brightly and decoratively painted. With a combination of wood structure and brick and stone infill, the courtyard offered a lively and varied setting for family life.

2.2 Thermal properties of the Courtyard House.

The careful design of the Courtyard House enhanced and further enabled the potential benefits of the southern exposure. An important feature of the progressive series of buildings in the courtyard house were t he platforms which increased in height as the buildings progress back. These platforms allowed for a solar envelope which maximized the solar access.

The design of the buildings within the courtyards included large overhangs and covered walkways to provide shade in the summer yet allowing light to penetrate at a lower angle in the winter. The addition of deciduous trees in the courtyard added to a total effect of a cool microclimate in the summer away from the hot dusty streets on the other side of the wall of the courtyard. The windows on both north and south sides of the building allowed for cross ventilation.

In the winter the southern orientation of the courtyard protected the buildings from harsh north winds. Movable shutters and translucent paper closed out the wind and cold at night while allowing warming southern light during the day.

The materials of the courtyard house (stone, brick and stucco infilled in a wood structure) provided a mass for thermal gain. The wood structure was used particularly due to the earthquake zone in which the imperial cities were built (even today Beijing is located in an earthquake zone). The traditional courtyard house was heated during the day by a "kang", a large brick or stone stove in the form of a large platform less than one meter high. Without a chimney, the smoke of the stove would exit through a wall cavity continuing to warm the thermal mass of the building. At night this stove platform would be used as a bed. The warm mass would keep the sleepers warm until morning when the use of the stove would warm the dwelling again.

Given the resources, the courtyard house and the grid city created with careful design and thought, the optimum climatic response for comfort and efficiency. The courtyard house not only represents a studied climatic understanding but also a thorough architectural interpretation of the Chinese culture of its time, a culture of which was based on the cosmos and an understanding of the world slowly revealing itself.

2.3 How courtyard houses are used today.

Today the courtyard houses are no longer inhabited by one extended family. With few exceptions the private courtyard house complex has become a part of the housing system of Beijing. Space within the courtyard house is now allocated to families similar to the newer high rise building complexes. The density in residential Beijing is approximately 550 people per hectre, requiring each courtyard house to be inhabited by four to six unrelated families. This adaptation requires that each family use one wing of the courtyard house, and the courtyard is infilled with kitchens and additional living units. These alterations affect the dwellings desirability as well as its thermal performance. Nevertheless, the traditional courtyard house generally remains the preferred housing type.

In 1949 a new Chinese republic required a new architectural housing type to meet needs and to respond to a change in philosophy. A new form evolved to achieve higher densities, while retaining the traditional Chinese principles for solar access and climatic response. The revolution also encouraged a baby boom; the population as a whole has more than doubled since 1949. The urban population has grown even faster, tripling in the last thirty years. The net result of this, despite a massive surge in construction is the decline in the average amount of living area per person from 4.5 sq meters in 1949 to 3.7 sq mt/person in the late 1970's.

3.1 Description

More housing at a higher density, needed to be built quickly. In the 1950's, three to four story apartment buildings were built; these were increased to 5 and 7 story "walkups" in the seventies. Today there are two basic types of housing being built in Beijing, the 5-7 story "walk-up" apartment building, and the 20-25 story elevator apartments.

These apartment buildings, often dozens of identical apartment buildings in row after row, represented remarkable housing production, however, the design of this housing epitomized the worst mistakes of 1950's and 1960's style western urban renewal.

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Title: Urban Plan of Apartment Buildings 

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Much like the courtyard houses, the placement and orientation of these buildings is carefully planned to allow each apartment southern winter sunlight. Although the passive solar principles were considered, several common energy efficient principles have to date been ignored in Chinese housing design.

The plan of apartment complexes are generally long rows of buildings stretching from east to west. In between the rows are common green areas. The dimension of this courtyard is carefully proportioned in relationship to the height of the adjacent buildings so as to prevent shading and allow for important solar access. With taller buildings these courtyards become very large up to 100 meters across. Living spaces and bedrooms are located on the south side, hallways, stairways and service rooms are located on the north side. Porches often overhang on the south side, providing extra sunny living area and summer shading for glazing.

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Title: Floor Plan and View of Apartment Buildings 

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Masonry technology is dominant in Beijing, the most prevalent systems are prefabricated concrete panels and cast in place concrete. In both cases the workmanship is less than ideal, but more importantly, there is little concern for the value of insulation. Windows are single glazed, (glass is in short supply) and wall sections have little or more commonly no insulation. The apartment buildings none the less are spacious by Chinese standards. There are the civilized facilities of running water, toilets, and cooking gas. They are modern and clean. In all these ways the apartment buildings are preferable to the courtyard houses.

3.3 How used today

Examining an apartment complex after several years of inhabitation shows some interesting patterns of use. The balconies often have additions, reflecting the occupants interest in birds, plants, or privacy. The "courtyard" spaces in between the buildings slowly become claimed by the occupants of the apartment buildings. Initially spaces are claimed near the edge of the building by the occupants of the adjacent apartment. Flower beds, fenced in courts, small cottage industry shops, etc. have appeared. Some actual small structures have been built in the large courtyards. In the larger courtyards these small "infill" buildings reduce the apparent size of the courtyard. These additions identify individual inhabitants within the stark monotony, the "claimed" territory become small oaises. Although a somewhat minimally defined dwelling to start with, over time even these apartments soften up and obtain a certain patina of home.

4.0 Comparison of the typologies

The traditional courtyard house and the apartment complex are the two primary housing types for the vast majority of the residents of Beijing. Access to sunlight and maximization of solar gain is a common design attribute of the two types. Both typologies have buildings elongated in an east/west direction, with primary glazing and use-spaces located on the south side. Both buildings lack the wall insulation and double glazing necessary to make them truly effective solar buildings. The courtyard building tends to have better cross ventilation than the apartment buildings because of its size and layout. Each typology alternates building with open space, creating courtyards which are associated with an adjacent building. Both buildings are primarily masonry.

As similar as these buildings are thermally, functionally they are very different. The processional aspect of the courtyard house, where spaces are slowly revealed in sequence, is absent in the contemporary apartment building. This quality of the courtyard house, which creates overlapping indoor and outdoor zones of increasing privacy is replaced in the apartment building with a single, shear wall. This lack of "semi-public" areas makes the apartment building interiors very private, and their courtyards very public. In the traditional courtyard house the sequential layering of spaces made a series of more public outdoor courts and more private outdoor courts; similarly the buildings had varying degrees of privacy. In today's courtyard houses, this intimate relationship is gone. With the public use of the courtyard by many families, there is very little privacy.

5.0 Some new prototypes

The housing problem in Beijing has been an ongoing subject of study for the students and faculty at Tsinghua University. The traditional courtyard houses promote cohesive, quaint neighborhoods, but they are overcrowded, decaying, and lack infrastructure. The apartment buildings give modern conveniences at the price of anonymity. One housing prototype which evolved at Tsinghua attempts to combine the best features of both.

Low-rise, high-density courtyard buildings were designed to have 6 to 10 families sharing a small 8 by 13 meter courtyard. 

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Title: Urban Plan of New Prototype 

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Title: Floor and Roof Plan of New Prototype 

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Title: Section/Elevation of New Prototype 

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These courtyard-type buildings allow up to approximately 500 persons/ha. Similar to the existing densities in residential Beijing, but with improved facilities and more area per person. The courtyards are once again designed so as to allow winter sunlight into all apartments. The abundance of small courtyards would have a moderating effect on the local microclimate. In combination with a reasonably insulative wall section and double glazing this design should perform well in the Beijing climate.

In addition to these thermal considerations, this typology has many advantages. 1) It is similar to the traditional courtyards in that it is inward looking. The exterior gives no clue to the interior of the building. 2) A small number of people inhabit each building, making the buildings seem like small neighborhoods again. 3) Their size in understandable. They are not inhumanly large, and the courtyards are pleasantly scaled. 4) They allow for variety within the typology. It is easy to make small changes which appear significant in the context of these little buildings.

All of these aspects seem to make this model a superior prototype that does not sacrifice solar access. However it remains to be seen if the physical buildings will meet the needs of the people of Beijing.

The traditional Beijing courtyard house has significant passive solar attributes exemplified by its orientation and solar access. Contemporary Chinese housing typologies have many passive solar qualities as well (most notably solar orientation and access), but the formal qualities which make the courtyard houses so attractive have been abandoned. Both housing types are not only a climatic response but also represent a culture as well. Demand and philosophy have required alterations for the Chinese housing type, yet key cultural and climatic housing needs remain design priorities. The availability of materials and the strict density requirements are certain to improve, the design of housing will be improved as well particularly with the addition of double paned glass, insulation and better building techniques. As these changes take place, the continued traditional properties in a new form such as the principles of the courtyard house applied to housing may help to reconcile the qualitative issues of high density contemporary housing in Beijing.

Bibliography

Jun-Hua, Lu: The Housing situation in The People's Republic of China Guest editorial in The International Journal for Development Technology, 1983, vol 1. Pp.255-257

Balcomb, J. Douglas and Sara A.: Passive solar in China: Traditional and new Conference proceedings 11^th National Passive Solar Conference USA June 7-44 1986 pp.392-396

Lui, et.all: The History of Chinese Classical Architecture Architectural Science Research Institute, China Architectural Industry Publishing House, 3^rd edition 1983.