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
The enclosure system regulates thermal and visual
comfort. By minimizing conditioning loads, its role in the design
of a sustainable building is crucial.
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.
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.
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
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
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
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:
- 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.
- 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.
- 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.
- 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.
- 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
- 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
- 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.
- 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.
- Centralized HVAC systems or planned locations
and proper sleeves for penetrations.
- 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
- Air barriers and flashing systems: These
systems are proven in their effectiveness to minimize energy
consumption and maximize building longevity.
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