A one-dimensional unsteady flow model with a moving pollutant source is used for calculating airflow velocity and pollutant distribution inside the single-track railway tunnel when a train passes through it. Calculations are made about the distribution of pollutant concentration inside the tunnel when a train passes through it under the conditions of different tunnel lengths, different amount of pollutant emissions, etc.

The substance of AC fresh air control is that fully utilises outdoor fresh air according to enthalpy of outdoor air, so achieves the goal of energy saving and improving indoor quality. The normal way is adjusting the amount of fresh air according to enthalpy which is calculated on the basis of temperature and humidity in and out door, this is called "enthalpy control". But because the cost of humidity sensor cell is high, its life is short, and it is very difficult to maintain, the long time and reliably running control systems are actually very short.

A numerical study was carried out to gain an understanding of the ventilation performance of solar chimneys with uniform heat flux from both walls. Results showed that a currently available predication method, which has been validated with narrow chimneys, may not be suitable for wide chimneys. It was also shown that for geometrically similar chimneys, the ventilation flow rate, Q, increases with the solar radiation intensity, q, and the chimney height, H, and can be well correlated by Q q1/3H4/3 regardless of height/gap ratio and the occurrence of reverse flows.

The aim of this paper is to verify the applicability of coupling thermal and multizonal simulation codes to the study of hybrid ventilated buildings. One of the main problems in hybrid ventilation building design is the evaluation of ventilation control strategies. This point has rarely been adequately developed during design phase by means of dynamic simulations analysis; often actually an insufficient analysis of control strategies it has revealed to be the first cause of complaints from the occupants. This paper aims at demonstrating a satisfactory solution of this problem.

Based on measured wall temperatures made by an infrared camera the flow and temperature fields were computed for an atrium. The nature of this atrium is a large enclosure inside a school building surrounded by halls and classrooms. Within a hybrid ventilation concept the stack effect during the summer time is used to form the main driving force for the night cooling of the classrooms. Time dependant computations were carried out to obtain the flow and temperature fields inside the atrium under various boundary conditions.

Decision about the use of natural, mechanical or hybrid ventilation system in a building should be taken at the early stages of the building design. While for a mechanical system the decision may be taken on the grounds of purely deterministic procedures, the use of natural forces requires a different approach. Therefore, a simple tool is needed which, given a few important and readily known building parameters and information about the local outdoor climate, enables the designer to determine the most suitable ventilation system.

This paper analyses buoyancy-driven natural ventilation assisted or opposed by winds in a building with thermal stratification. Theoretical analysis shows that the ventilation flow is mainly characterised by two air change parameters, namely a buoyancy air change parameter and a wind change parameter, as well as the ventilation openings. It also shows how the clean zone height is affected by ventilation openings. Our new analysis also reveals that the hysteresis behaviour found when uniform temperature distribution is assumed also exists in buildings with thermal stratification.

As part of IEA Annex 35 "Hybrid Ventilation in New and Retrofitted Office Buildings" a number of pilot study buildings are monitored for demonstration of hybrid ventilation performance. The monitoring programmes investigates the performance regarding indoor air quality (IAQ), thermal comfort, control strategies and energy consumption. This paper presents detailed measurements from the Danish contribution. Detailed results from short-term measuring periods are presented.

This paper justifies the need for an integrated approach to building performance assessment and provides examples of the technical appraisals that may then be enabled. The contention is that the use of design tools which focus on a single domain will result in sub-optimum design solutions in terms of indoor air quality, occupant comfort, energy use and environmental impact.

The determination of building insulation levels is an indispensable part of low-energy residential building design. It is necessary to study the impacts of varying insulationlevels of outer walls and roof on room heating loads and cooling loads per square metre. Although diversity of researches on this subject have been carried out over the past years, simulation models have not been employed to evaluate the energy saving effect of different insulation levels all year, and the results were not quantitatively analysed.