Several models have been developed to study the airflow pattern and thermal distribution in buildings. This paper describes the development of a zonal model that may be incorporated into existing building energy analysis programs. The modeling is detailed in three applications describing how such a model can be simply applied. The model predictions were then compared with measurements and/or Computational Fluid Dynamics (CFD) model prediction.

This paper reports on research into the fundamental fluid mechanics mechanisms that lead to thermal stratification in a naturally ventilated room containing sources of heat, or cooling. This aspect of natural ventilation has an important influence on both air exchange rates and thermal comfort in a naturally ventilated space. Particular attention is paid to the situation where the major source of heat is a vertical surface, such as a wall heated by solar insolation, for example.

During design phase, Liberty Tower of Meiji University, a high-rise building located at the center of Tokyo Metropolitan area, several testing methods were applied to ensure the effectiveness of the various components used in the principle of hybrid ventilation system design. Its special design feature is the "wind-floor'', whereby the central core is planned to induce natural ventilation for every floor by creating stack-effect.

Thirty five occupants of twenty five naturally ventilated rooms can operate supplementary cooling and heating equipment and windows independently to control their local thermal conditions and ventilation in accordance with their personal comfort requirements. Preliminary studies suggest that the use of the supplementary cooling equipment is closely related to outdoor thermal conditions with limited recourse to it in mild weather and resultant substantial energy saving in comparison with consumption that might be expected in a conventionally air conditioned environment.

Computational Fluid Dynamics (CFO) modelling techniques have been used extensively and with considerable success for many years in providing environmental and physiological flow conditions in applications as diverse as:

The on-the-ground experience of a domestic design and construct company (Ecobuild Pty Ltd, for which the author is the designer and director), is illustrated as a case study for the application of domestic natural ventilation in the temperate climate of Sydney. Factors limiting the general domestic application of natural ventilation are discussed. Requirements of a domestic ventilation system in Sydney are listed. Examples of domestic natural ventilation designed the company are illustrated. Preliminary results are discussed. The need for domestic IAQ research and standards is stressed.

Many existing offices either overheat in the summer or use excessive amounts of energy to maintain acceptable temperatures. The reasons are increasing internal heat gains from office IT equipment, poor efficiency lighting systems, density of staff and original poor building design causing excessive solar gains. The trend is for problem offices to have AC systems replaced - at the end of the life of the existing services - or installed in previously naturally ventilated offices when refurbishment occurs.

This paper aims to identify major characteristics of hybrid ventilation systems, whereby a clear distinction is made between ventilation for Indoor air quality control and ventilation as part of a strategy for thermal comfort in summer. Various building projects are used as illustration for the classification.