Urban air quality makes headline news, and a recent Royal Commission report has stepped up the campaign against pollution from road vehicles. Better detection methods and monitoring mean that we are learning more about the air that we breathe.

In the poorer countries of the world, where energy consumption per capita is lower than in the industrialized nations, the process of rapid urbanization is a strong feature of the dynamic of economic development. Population growth rates in cities are consistently higher than in the countryside, due both to higher natural increases and to net migration. Although the majority ·of Asia's population is still rural, this dominance is expected to shift sometime around the tum of the century.

The Ventilation Standard HASS-102 of The Society of Heating, Air-conditioning andSanitary Engineere of Japan (SHASE Japan) was revised in November, 1997. The title of therevised standard is Ventilation Standard for Acceptable Indoor Air Quality. So far, the oldVentilation Standard, which was issued in 1939, had been used for a long time. The task forrevision was undertaken by the Sub-committee on Ventilation Effectiveness and Standard(chaired by Murakami) of SHASE Japan.

Today, the development of new technologies to improve building envelope performances ishighly encouraged and provides a clear challenge for designers and researchers. In thiscontext several typologies of active envelopes have become very popular. The paper startswith an overview of the history and the performances of active envelopes in the context ofurban design.

Ventilation of buildings in urban areas may result in high internal concentrations of traffic pollutants if air intakes are positioned where external concentrations are highest. This paper presents the results of a wind tunnel study into different wind-driven natural ventilation strategies for a building situated close to a busy road.

The aim has been to determine ventilation rates and risk of moisture damage in three modernschools with passive stack ventilation. The users are supposed to control the ventilation byusing the lantern windows and the outdoor air is assumed to enter through an undergroundduct. The paper presents results, analysis and conclusions from the performed measurementsand calculations.The ventilation rates are sometimes low and vary with the use of the windows in the facadeand the lantern. It is, however, always possible to arrive at a sufficient ventilation rate.

A dynamic simulation of the ventilation processes and the thermal behaviour of an office building is developed. This is used to investigate two aspects of night cooling with natural ventilation: the control strategies and the required ventilation open

Heat recovery in ventilation systems for office buildings in cold climates is necessary for tworeasons:1. To obtain acceptable indoor thermal comfort by preheating of fresh air,2. To reduce ventilation energy lossThis paper describes a pilot system built in the laboratory of the Norwegian Building ResearchInstitute, NBI, based upon the concept of an advanced fan assisted natural ventilation systemwith heat recovery. The concept was developed by NBI.

This paper identifies successful ways of applying natural ventilation to non domestic buildings locatedin urban areas. Whilst noise and contaminant pollution sources are a problem methods of avoiding theseemissions are discussed. A review of literature has established that pollution problems arise for buildingswhich are in close proximity to roads, railways, airports and local industries. Location of ventilation airinlets will affect the quality of indoor air, therefore it is essential that they are located in ways thatminimise the ingress of external pollutants.