The development of new highly sensitive detection techniques for particle bound polycyclic aromatic compounds (PP AH) on the nano-particles of traffic born soot open a new dimension for real time measuring techniques for air exchange rates in buildings in operation. The principles and first measurements are presented and demonstrate the principal applicability of this method.

Air change rates in a cross-ventilation model were measured from the decay curves of video image signals obtained by the step down method assuming perfect mixing of tracer mists inside the spaces. Wind tunnel test results led to the following conclusions. 1) Ray extinction due to lighting scattering did not affect the measurement accuracy of the air change rates in the two-dimensional model. 2) Tracer mists in a diameter between 0.25 μ m and 2.0 μ m produced the same measurement accuracy.

A set of formulae for natural ventilation by thermal buoyancy is derived for a room with two opening and with a linear temperature stratification. The formulae are based on the fundamental flow equations, and they cover air velocities, temperature differences and ventilation rates in relation to opening areas, opening position, net heat input, building geometry, and temperature stratification. The temperature stratification can simply be taken into account by introducing a stratification factor E and by using the mean difference between indoor and outdoor temperatures.

Solar chimneys are often used to extract air from a building by thermal stacks, while subfloor plenums are used to passively cool air before it is supplied to a building. This paper examines the overall flow pattern in buildings with both solar chimneys and subfloor plenums. For a multi-zone flow system in which each zone has only two effective openings, an analytical solution is derived. A sufficient condition for upward flows to occur is derived from the analytical solution.

The light well located in the center of high-rise apartment building in Japan is called "Void". Gas water-heaters settled in Void discharge the exhaust gas into Void so that the enough opening area has to be designed at the bottom of Void to keep the IAQ in Void. In order to secure the IAQ in Void, a simple zonal model to calculate the ventilation rate induced by the wind force and the thermal buoyancy through openings at the bottom of Void with heat sources like water heaters is presented. And the accuracy of this calculation method is examined by wind tunnel test.

This paper compares two well-known modelling approaches for natural ventilation in a multi-zone building with thermal stratification and large openings. The zonal approach in this paper assumes a fully mixed condition in each zone, and considers the bi-directional flows through all large openings. The zonal model is integrated into a thermal analysis code to provide simultaneous prediction of both ventilation flow rates and air temperatures in each zone. The CFD approach uses a finite-volume method for turbulent flows.

In a hot climate, a large amount of solar heat irradiates on a roof and it is transmitted to an occupied space beneath it through an attic. To interrupt this heat to attain a comfortable condition in the occupied space, ventilation of the attic is an important and effective measure. There are two ways of the ventilation, one is natural and the other is forces ventilation. The former measure should be considered prior to the latter from such reasons as simplicity in practice and power saving.

Airflow through houses from onshore coastal breezes in warm humid tropical climates is the principal passive means of achieving indoor thermal comfort when air temperatures exceed 30°C and relative humidity exceeds 60%. Estimates of indoor natural ventilation cooling potential have been based on indoor wind speed coefficients determined from boundary layer wind tunnel tests combined with wind frequency, air temperature and relative humidity data.