96 human subjects (18 years age students from a Swedish high school) were submitted in an experimental room furnished as a classroom to different air flows issued from different ventilation systems : displacement with constant air flow rate, alternating between displacement (floor diffusers) and mixing ventilation (ceiling diffusers) with constant flow rate, mixing ventilation with varying flow rate, displacement with constant flow rate and with ceiling fans to generate air motions alternatively on and off.
This study describes the development of a three dimensional (3D) Lagrangian code of particle transport in indoor turbulent flows. This approach consists of integrating transport equations for each particle at each time step to determine successive positions of the particle. The first challenge was to calculate instantaneous velocities of the airflow. The mean component of these velocities was calculated by a classic CFD code. A stochastic process based on the Gosman and Ioannides method generated the fluctuating component. Corrections were applied to better fit experimental results.
This paper presents the investigation results on a simulation program, which calculates the particle trajectory under different airflow patterns in the multi-zones structure building. The numerical simulation is first used to predict airflow pattern and ventilation performance. Then, the particle movement is determined by employing Lagrangian method. The simulation identifies the characteristics of ventilation and indoor air quality.
The study presented in this article concerns the numerical simulation of airflows and occupational exposure to household contaminants. A finite volume code (CFD) is used to simulate a single-family house with several ventilation, heating, and climatic conditions. The concentration and occupational exposure levels of household contaminants CO2, CO, HCHO, NO2, and water vapour, all from human metabolism, along with those from gas cooking and smoking, are evaluated over a day for a generic occupational schedule of four family members.
Measurements of indoor air quality indicators (temperature, humidity, dust, biocontaminants and CO2) were performed monthly during one year in a French office building. Air filters of the air handling unit of the building have also been characterised on site and in laboratory. Detailed results of these measurements are given and analysed.
This contribution reports on investigations about the performance of decentralised ventilation units with heat recovery. Such units can be easily installed in individual rooms and therefore offer an interesting alternative to central ventilation units. Nevertheless these units exhibit some problems. Experimental examinations of two commercial decentralised units showed that the real effectiveness of heat recovery was always below 50 % and that considerable leakage between the air ducts can result in poor indoor air quality.
This paper proposes a new mode of ventilation for indoor airflow. Computational results show that with properly designed supplied air velocity and volume, locations of diffusers and exhausts, the proposed system should be able to maintain better thermal comfort with a smaller temperature difference between the head and foot level, and possibly lower energy consumption, if compared with conventional systems. It looks promising that better indoor air quality (IAQ) in the breathing zone could also be achieved but that further work is needed to determine if IAQ benefits are significant.
The study conducted by the US Government Accounting Office in 1995 says that 25 % of the nation’s schools are plagued by IAQ problems, even higher percentage of schools having IAQ problems is reported by the Environmental Protection Agency (Johnston and D
Ventilation and indoor air characteristics were measured in 63 apartments for elderly people in Finland and residents were inquired about indoor climate. Results are shown and analysed.
Literature was reviewed about underfloor systems and engineers having experienced these systems on completed projects were interviewed. Underfloor air distribution systems improve thermal comfort , indoor air quality and user satisfaction.
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