The Air Lock Floor and the Pressure Ring are two effective measures for control of air flow directions between rooms or zones in buildings. They create a pressure hierarchy that controls spread of pollutants. Here an example has been given for radon from a crawl space, odours from a bakery into a dwelling above and an isolation chamber with a leaky facade. The Air Lock floor can operate with a 7 W fan and at the same time extractthe normal dwelling ventilation flowrate. Used in the ground floor, the Air Lock Floor results in a warmer floor and contributes to energy savings.
Measurements of interzone airflow and movement of aerosol particles were carried out in an environmental chamber. SF tracer gas and oil-smoke particles were used for this work. A series of measurements were conducted to investigate the effect of parameters such as interzone temperature difference and size of opening on the flow of aerosol particles. The particle deposition rate on thesurfaces of the chamber together with algorithms for interzonal particle flow through the openings were determined. Results were compared with those obtained using the tracer-gas.
A series of laboratory experiments are described which investigated the effect of surface roughness on the air flow characteristics of simple, straight-through, no-bend cracks with smooth and rough internal surfaces. Thecrack lengths, in the direction of flow, were 50.8mm and 76.2mm. For the rough cracks the roughness was simulated with two different grades of commercially available emery-cloth (grade 60 and 100). The effect of roughness on the reduction of air flowing through a crack is also discussed.
This paper is concerned with measurement of air and aerosol particle exchange efficiency in a single zone chamber. Aerosol particles and tracer gases were injected into the chamber and their concentrations were monitored as a funtion of time. The chamber was provided with supply and exhaust terminals which allowed various airflow and particle patterns (e.g. piston flow, displacement flow) to be investigated. The effect of airflow pattern on deposition rate of aerosol particles on the surfaces of the chamber was determined.
Indoor air quality, comfort and energy use in buildings are largely dependent on the performance of HVAC systems. However, the pressure loss factors available to the designer show large discrepancies depending on the source of the data. In particular there are very few data regarding the effect on k-factors of interactions between duct components in close proximity. This paper describes measurement and computational fluid dynamics (CFD) modelling of pressure loss in HVAC system components. The results were compared with those data given in the ASHRAE and CIBSE guides.
This paper presents a measurement technique to perform quantitative visualization of room air flows. The visualization is done by discrete particles, namely helium-filled soap bubbles, illuminated in a plane light sheet generated by a point light source in combination with a special lens. The recording is done stereoscopically with 3 standard cameras by streak photography. The scanned negatives are analysed digitally. The method is able to give the three-dimensional instantaneous velocity field of room air movements, also in real-scale.
This paper presents a trial of applying a CFD package into an air movement study in an old English church. The possibility of adopting computational modelling in a complex shaped building has highlighted the problem encountered due to the large difference in scale between thermal elements and building enclosure. The results have demonstrated that there are still significant problems to be overcome in using CFD models in such situations.
Building airtightness data are essential for design and model evaluation. An attempt has been made with the Numerical Database to compile data appropriate toinfiltration and ventilation studies. These cover the air leakage characteristics of building components, the characteristics of buildings themselves and data on wind pressure distributions. AIVC Technical Note 44 (Orme, Liddament, and Wilson 1994), contains detailed summary tables and graphs of the information stored in the computer Database, together with a complete list of references.
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