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DETAILED RESEARCH PLAN

Methodology
This project focuses on construction and evaluation of demonstration buildings that incorporate energy-conservation features. We will continue to use the methods expanded upon in the first proposals.

Formation of partnerships.
The faculty at MIT has already had several exchanges with Chinese colleagues. Over the last year five MIT faculty members have made three visits to China, visiting Beijing, Shanghai, and Shenzhen. The MIT and Tsinghua faculty held a one-day seminar at Beijing for interested designers, developers, equipment suppliers and researchers. New sustainable design and technologies were described and discussed. Meetings were held with members of major design institutes at Tsinghua University in Beijing and at Tongji University in Shanghai. These institutes are responsible for the design of many large building projects in China. An agreement was reached between MIT faculty, engineering colleagues at Tsinghua University and Tongji University, and the two design institutes to develop demonstration projects for sustainable buildings. Last spring, faculty from Tongji University in Shanghai traveled to the U.S., supported on AGS funds.

Selection of target sites.
Currently, target sites comprise a diverse group, with the most promising site located in Shenzhen, The site is comprised of 2 hectares, with a floor area ration of 1.5. We have recently submitted the schematic design to Vanke Architecture Technology Research Center and hope to take an active role in the next few months during the detailed design and construction document phases.

We have targeted a second site outside of Beijing, in a development called Hui Long Gong. The total land size is seven square kilometers. MIT and Tsinghua University have been asked to develop a plot of land of about 10 hectares. This is a model where urban factors and construction techniques, in addition to technologies explored in other projects, should be investigated due to the size of the project. The inclusion of faculty and students from Tsinghua University in this project will facilitate close planning of the demonstration and proper evaluation of proposed designs. In addition, the collaboration also will encourage considerations such as building codes and buyer acceptability, and careful monitoring of the demonstration after it is built and occupied.

Evaluation of building density, size, and shape.
Many new residential construction projects in urban areas in China favor high-rise buildings. Pressures on land use and code requirements for distances between buildings are often cited as reasons for this choice, which runs counter to widespread acknowledgment that buildings of lower height provide more enjoyable living conditions and are more easily shaded with vegetation. MIT will explore and evaluate alternative siting and sizing of buildings, using the various test sites as a starting point. Results will be shared with all team members and will be important for investigation of airflows around buildings (UT and ETH) and for weighing land and building construction costs.

To protect from cold winter winds, several measures are proposed that have to do with building shape, orientation, clustering, and the immediate surrounding. Moreover, to keep houses cool in summer, advanced natural ventilation is recommended. For both design tasks, a detailed knowledge of external aerodynamics is required. It is insufficient to consult tables with typical surface pressures. Instead, computational fluid dynamics predictions of the velocity field in the immediate surroundings can provide detailed information about the interaction of wind and building geometry. Roof slopes, edges and shape of the building envelope, placement of windows, smoke stacks, and vents, and clustering or joining of residential units can be optimized. Exhaust openings in the roof with passive Venturi suction driven by wind, can be designed and properly shaped. Hot updraft on south-facing facades of high-rise residences can be simulated, and consequences for open windows clarified.

For residential buildings in the climate as in Beijing, buffer zones such as terraces enclosed by glass windows or winter gardens are effective to reduce heating loads during the winter by collecting solar energy. When solar irradiation is intense and the elevation of the sun high, the terraces provide shade to the inner zone. During the period when natural ventilation works well, these spaces should be open to the outdoors. The impacts of these "half-open spaces" on the air movement and heat transfer in and around buildings need careful attention. In the proposed research, ETH and UT will use CFD to investigate these mechanisms and to provide information for optimum design of these spaces.

Evaluation of specific technologies.
Technologies will focus on natural ventilation as an alternative to mechanical cooling and on selected other strategies for passive heating and cooling. These appear to be the most promising approaches for sustainable Chinese housing. There are a number of generic issues that must be considered to insure that such systems will have a substantial impact on the building performance. Within this work we will consider the major implications of such systems and develop general design rules.

Chinese designers would like to include natural ventilation in the design of their new buildings. This is a complicated issue that involves the design of building interiors and window placement to facilitate airflow. In addition, the proximity of neighboring buildings and the building shape will influence air circulation outside the building and in turn natural circulation throughout the building. There is the desire to include natural ventilation in high-rise buildings, a difficulty compounded by the interaction of buoyancy and wind driven flows. If natural ventilation could properly be designed in a building, our initial simulations suggest that natural ventilation combined with nighttime cooling and thermal storage in the walls would eliminate most of the need for air conditioning in Beijing on an average summer day.

The research team would consider the general issue of natural ventilation from a variety of viewpoints:

  • Air flow around building exteriors: UT, ETH
  • Advanced ventilation concepts: UT
  • Natural ventilation within buildings: MIT, ETH
  • Evaluation of sustainability: EPFL, MIT
  • Integration into Building Design: MIT, Tsinghua U

In a similar fashion, the research team will consider generic new designs and technologies to include solar heating, dehumidification, shading techniques (U of Tokyo), and other passive measures (Tsinghua U.). The practicality, impact on sustainability and general design rules will be considered. The sustainability guidelines developed by EPFL will be used to carry out the evaluation. Promising systems will be considered for inclusion in demonstrations.

Tool for evaluation of buildings by assessment of health impact of the indoor air quality.
Indoor Air Quality (IAQ) is closely linked to energy consumption and therefore is relevant to sustainability of buildings. There are often trade-offs between improving IAQ, reducing energy consumption, and maintaining thermal comfort. IAQ is one of the important factors that affects welfare and health of occupants. Therefore, a prediction model that can simultaneously treat various factors is desired to realize good design of sustainable buildings. The model will be able to evaluate effects of natural ventilation or thermal storage capacity of buildings, taking unsteady-state phenomena into account.

ETHZ will develop a simplified natural ventilation assessment technique. This method would serve to evaluate the effects of various factors such as ventilation methods (natural ventilation, mechanical ventilation, etc.) and materials on IAQ. The envisaged tool can evaluate energy consumption, thermal environment (air temperature and radiative temperature), and IAQ simultaneously. This computer model can be employed to quantify overall effects of the measures taken in the construction project. A concept of occupant contaminant inhalation will be used for a long-term assessment of health impact of IAQ. The design tool will help to create buildings with low energy consumption without compromising comfort and occupant health.

Development of design alternatives.
MIT architecture faculty and students, assisted by engineering faculty and students, will begin to prepare a series of design alternatives for the demonstration buildings in the Beijing Tian Hong project. In addition, MIT will act as consultants for the design development and construction documents phase for the design of the Shenzhen project, researching more aspects of detailed design.

Development of final design.
MIT, Tsinghua and Tongji Universities will take an active role in the design development of both Shenzhen and Tian Hong projects. This will involve frequent contact with architects

Construction.
Tsinghua University will document key aspects of building construction as they relate to energy-efficiency features. For example, fixed shading of windows may require more complicated concrete formwork. MIT will begin to catalog specific materials that are readily available in China, and will look into finding Chinese manufacturers and suppliers.

Evaluation.
After construction, Tsinghua University and MIT will document the performance of the demonstration buildings, including apartment-level energy consumption; temperature, lighting levels, airflow and insulation measurements; and occupant thermal comfort surveys. University of Tokyo will design methods for monitoring.

Preparation of guidelines for future demonstrations and wide-scale adoption.
All of the institutions participating in this project will collaborate in preparing guidelines for future demonstrations, based on lessons learned from the first building. With support from Tsinghua University, MIT will conduct a series of workshops intended to educate both developers and architects in China as to technologies and design approaches utilized during this project.

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Last modified on November 22, 2000 by china@juintow.com.
 
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