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.

Mechanical and natural ventilation systems have developed separately during many years. The natural next step in this development is development of ventilation concepts that utilizes and combines the best features from each system into a new type of ventilation system - Hybrid Ventilation. Buildings with hybrid ventilation often include other sustainable technologies and an energy optimisation requires an integrated approach in the design of the building and its mechanical systems. Therefore, the hybrid ventilation design procedure differs from the design procedure for conventional HVAC.

An historical background of fluid mechanics used in computation of natural ventilation is provided. Unresolved issues in computation of natural ventilation for thermal comfort are discussed. These issues include the influence of building porosity on wind pressure difference coefficients; wind shelter effects; indoor air flow resistance; air flow for thermal comfort and heat stress relief; air flow computation techniques; and natural ventilation in home energy rating schemes.

The Air Infiltration and Ventilation Centre was established as a jointly funded International Energy Agency activity in 1979. This paper seeks to describe some of the work of the AIVC and outline its evolving structure which is aimed at strengthening the link between research and application.