approach

building systems

     siting
     envelope
     mechanical
     materials
     interiors

heating strategies

cooling strategies

policy strategies

consumer notes

Our approach to design of housing buildings in China involves the integration of technology and design issues. Further, the treatment of a building as a system composed of siting, enclosure, mechanical, materials, and interiors subsystems is essential. Other approaches such as analyzing heating, cooling strategies in addition to policy and consumer education strategies are central to the design of a sustainable building.

Components of the Building System

The siting of a building

The siting of a building refers to the relationship between building and the larger contexts of community and region. In order to construct a sustainable building, it is essential to take into consideration factors beyond the site boundaries. Environmental impact should be minimized when siting buildings. One method, for example, is to cluster buildings to leave undisturbed land areas. Furthermore, it is important to recognize the value of existing buildings. When possible, existing buildings, streets, and structures should be reused.

Orientation of building along the east-west axis can decrease summer and winter loads. Wind directions and speed, including changing wind patterns and nearby buildings and vegetation, can further decrease these loads keeping out winter winds, while benefiting from summer breezes.

The envelope or enclosure system

The enclosure system regulates thermal and visual comfort. By minimizing conditioning loads, its role in the design of a sustainable building is crucial.

Thermal Comfort

Orientation is an important factor when considering the enclosure system. Openings to the east and west are difficult to shade, and thus should be reduced when designing the facades of the envelope. East and west sides of buildings can be designed to incorporate vertical fins, deep recesses, or other strategies designed to divert direct sunlight before penetrating the building.

Another important factor is the performance of glazing, including specific aspects of glass such as the shading coefficient and visual light transmittance. A balance between these, such as the use of advanced glazing and coatings can decrease solar gains while providing natural daylight.

Aside from fenestrations in the fašade, designers should understand building mass and its ability to control thermal comfort by stabilizing temperature changes. Other factors indispensable to thermal comfort include the reduction of infiltration, integration of insulation, and management of moisture movement.

Visual Comfort

Bearing in mind the above recommendations, the enclosure system must provide a visual connection from interior to exterior to provide inhabitants with psychological benefits. This link to the exterior environment can provide awareness of weather, seasons, daylight, and outside activity. Studies have shown that people are more productive and comfortable when building design incorporates both natural daylighting and well-designed electric lighting systems. Further, it is advantageous to facilitate user controls over lighting conditions and ventilation via the design of operable blinds, moveable shades, or operable windows. In addition to window openings, surface treatment, color and room sizes play a large part in the design of visually stimulating yet comfortable spaces.

Mechanical System

Much of the design of the mechanical system involves successful integration of other systems, such as envelope and illumination design. For example, optimized enclosure design, natural ventilation, natural daylighting, and passive solar heating and cooling can dramatically increase user comfort and decrease costs and by lessening loads to the HVAC system. These costs take the form of both initial costs, such as those needed for equipment, and long-term maintenance and operation costs.

To further reduce these loads, careful space planning, such as locating spaces which require less conditioning to the north side of the building,

Indoor air quality (IAQ) is an important issue in building design. A rising number of IAQ and sick building syndrome (SBS), such as learning disabilities, allergies, and emotional and physical disorders, has

Need to finish

Materials

The selection and use of building materials, in particular for large scale housing projects will have significant energy, cost, and comfort implications. The impact of the current and imminent growth in China's construction sector represents a potential new prominence in world resource consumption.

Careful and creative selection of materials and design and detailing of installation can significantly mitigate this impact. The use of renewable materials should be given preference to the use of non-renewables. Reusable and recyclable materials should be give preference to non-recyclable, non-reusable materials. Consideration should be given to the project's role in carbon dioxide chains; outputs and inputs should be balanced. Designs must be reasonably constructable; the need to import either labor or materials should be minimized and limited to those resources that have significant and repeatable

The building envelope, its walls and roof, should be instrumental in minimizing the consumption of non-renewable resources during the life of the building. This will minimize negative impacts of fuel usage including operational costs.

 The team recognizes potential risks and benefits of the current transition to occupant ownership. The environmental risks include: The effect of larger units, and the resultant per capita material and energy consumption; Comfort zone evolution to a more limited region that may will require more responsive buildings and HVAC systems; The decentralization of knowledge base to the market eliminates the potential for a unified approach The associated benefits include the owner's increased stake in their dwellings may lead to improved maintenance due to onsite care taking and responsibility. Also, the potential of decentralized knowledge base may provide means to implement new solutions. 

Problems to address:

    1. AC units: Individual units are not efficient, and typically are not carefully installed. Energy inefficiency is compounded by air infiltration through unsealed condensate and electric lines. Water leakage may present a long-term durability and maintenance issue near these interruptions in the façade. and aesthetics).
    2. Lack of insulation. There is conflicting information regarding the use of insulation in existing and recent construction. Insulating value is typically attributable to clay or masonry materials that have very high thermal conductivity. Their advantage in thermal lag are advantageous only when mean diurnal temperatures are in the comfort zone. Therefore insulation will be beneficial in most regions. The industry is currently unaccustomed to designing insulated walls.
    3. Window construction: Typical systems are single glazed and leaky (loose-fitting). According to the Ministry of Construction, windows and doors account for 50% of energy loss in Chinese buildings.
    4. Effective use of concrete: As the transition continues from clay-brick to concrete construction, the overuse /over design of concrete structures poses a significant environmental hazard due to its large embodied energy and the significant volumes of carbon dioxide emitted during its manufacture.
    5. Loss of agricultural land due to clay mining. Apparently, 10,000 hectares of farmland is destroyed annually to make clay brick. The apparent alternative is concrete blocks. This technology is, like clay brick, also high in embodied energy. 

    Replacing clay brick as a wall building material has been a crucial step toward achieving a sustainable development for China. In the case of clay brick, it is already a state policy to replace it with CMU and other building materials. One report says that the quantity of wall building materials used in China in 1992 was equivalent to 525.3 billion clay bricks with 8% replaced by new wall materials, which then would come to 483.2 billion clay bricks and equivalent to 707,000,000 cubic meters (48 million tons of coal were burned when these bricks were fired). It is estimated that 800,000,000 square meters of housing will be built across China each year from 1996 till 2000 and that 830,000,000 square meters will be built each year from 2000 to 2010, which add up to 12.3 billion square meters (in addition to industrial and infrastructural construction) and would use 3 billion cubic meters of clay brick if they are all built with clay brick and burn 200 million tons of coal. Another estimate says that China's arable land per capita has decreased from 1,867 square meters in 1952 to 934 square meters at present and the decrease is still continuing for the sake of making clay brick at 10,000 hectares each year.

Proposed Considerations

    1. Integrated design approach: Holistic thinking should be the first consideration in improving the quality of housing. Integrating the consideration of materials with the planning of mechanical systems can eliminate aesthetic problems while avoiding damaging moisture penetration and energy consuming air infiltration. A similar approach may be taken in the planning and detailing of window openings. Vast improvements may be made on each of these fronts by complete planning and rigorous follow-through during construction.
    2. Windows: A lot of money can be spent improving the quality of windows. High-tech solutions are available globally that would provide a radical improvement on the energy losses and associated discomfort related to leaky windows. However, importing technology shouldn't be considered as the only solution, or even necessarily the best solution. Importation suggests exporting jobs and money, and requires the expenditure of time, money and energy for the transport of products. If windows are to be imported, consideration should be given to purchasing only frame stock. This will reduce the transportation associated with heavy glass units, while concentrating on accessing the higher-tech and highly engineered frames. The higher quality frames will mitigate a majority of the energy and comfort issues if installed correctly.
    3. Insulation: The most expensive way to insulate a building is to leave the insulation out of the building. The resultant energy consumption of buildings without insulation is more expensive than simply putting insulation in the wall to begin with. The most effective location for building insulation is on the outside of the structure where it can be run past the floor slabs, creating a continuous protective layer for the building thereby minimizing thermal bridges.
    4. Centralized HVAC systems or planned locations and proper sleeves for penetrations.
    5. Apply vernacular / regional technologies: The environmental impact of concrete construction can be minimized by careful engineering of the structures to avoid wasting material. Local coal-burning power plants should be considered as mines for fly ash, a material that can be used to replace portland cement and thereby reduce carbon dioxide emissions of the concrete mix.
    6. Air barriers and flashing systems: These systems are proven in their effectiveness to minimize energy consumption and maximize building longevity.

Interiors

Illumination

Acoustic

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Last modified on December 13, 2000 by china@juintow.com.
 
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