English

Daylight design for “extremely” obstructed urban environment is a relatively uncharted area of scholarship. The reason might be that the problem has not been critically important. No city in the world has an urban density as high as Hong Kong. Deisgning and providing adequate daylight into buildings is a difficult challenge. A key question designers often ask is: If there is a need to build a high density city, what should it look like? What one should or should not do? There are many design variables. This study examined one of them: building heights.

The impact of building regulations on the final form of a design can be quite significant. At the same time, increasingly stringent and more performance-based regulations are leading to a greater reliance on simulation and analysis as a fundamental part of the design process. As a result, the traditional design validate- redesign approach is becoming less viable. This paper argues that an alternate approach based on the generative potential of building regulations is more effective.

This paper presents a study of windbreak sheltering effect on the outdoor open space using Computational Fluid Dynamics (CFD) techniques and the wind tunnel experiments carried out for validating the CFD models. Although the influence of a windbreak on the reduction of wind speed is fairly well known, it is still uncertain how this influence will be affected by the buildings in an urban area where the windbreaks are placed for providing better wind comfort to the people in outdoor open space.

In building simulation, as in several other domains, traditional monolithic simulation codes are still in dominance over simulators based on symbolic equations in a general modeling language. Introduced in 1998, IDA Indoor Climate and Energy has become the first widely spread thermal building performance simulator based on the new technology. Developing a full-fledged dynamic whole-building simulation pro- gram is a formidable endeavor in any  setting  and since the first beta version in 1997 a number of les- sons have been learned.

In this paper an approach for pre-calculating building façade incident irradiance levels under a typical, yet computationally complex, external shading device with state-of-the-art ray tracing simulation techniques is presented. The impact of accurate modelling of direct solar, diffuse sky and inter-reflected irradiance components on resulting levels of thermal comfort and energy demand is analysed and recommendations are given for improvement of modelling capabilities.

In  an  existing  integrated  building  design  tool, BSim2002, a 3D building model can be created. The model can be used for thermal simulation, but also for other purposes, e.g. for calculation and visualisa- tion of the solar penetration into a building. The model can be exported to other programs, e.g. for daylight calculations and visualisation.

For the multi-room ventilation calculations, bi- directional flows or counter flows in openings have been rarely taken into consideration and only uni-directional flows have been allowed for the calculation.

Traditionally, the simulation of buildings has focused on operational energy consumption in an attempt to determine the potential  for energy savings. Whilst operational energy of Australian buildings accounts for around 20% of total energy consumption nationally, embodied energy represents 20 to 50 times the annual operational energy of most Australian buildings. Lower values have been shown through a number of studies that have analysed the embodied energy of buildings and their products, however these have now shown to be incomplete in system boundary.

To   provide   additional   validation   data   for   the multizone airflow and contaminant model, CONTAMW, experiments were performed in an occupied 3-story townhouse in Reston, VA. A tracer gas, sulfur hexaflouride (SF6), was manually injected within one room of the house and the concentration of SF6 was measured in each zone. This same process was then recreated in CONTAMW and the resulting predictions were statistically compared to the measured values. A total of 10 experiments were conducted and simulated between May 2000 and June 2001.

Even though simulation is being increasingly used in design of modern buildings, the full potential of simulation is usually not achieved. To improve building and HVAC system performance, designers usually guess different values of design parameters and then redo the simulation without actual knowing if the guessed value will lead to improvement. This is inefficient and labor intensive. In addition, if the number of design parameters being varied exceeds two or three, the designer can be overwhelmed in trying to understand the nonlinear interactions of the parameters.