Ventilation effectiveness - the AIVC guide.

Sandberg and Skaret differentiate between the terms air change efficiency and ventilation effectiveness. Air change efficiency is a measure of how effectively the air present in a room is replaced by fresh air from the ventilation system whereas ventilation effectiveness is a measure of how quickly an air-borne contaminant is removed from the room. The AIVC guide covers ventilation effectiveness and related concepts. It shows the origins of the concepts used, provides proofs of essential formulae, and suggests standard symbols and definitions.

Turbulent modelling of airflow patterns and ventilation effectiveness in a half scale office building.

The concentrations of indoor pollutants should be maintained below recommended values at all occupied locations at any time. A design method based on minimal air change rates may not be satisfactory, since the ventilation effectiveness is determined not only by the nominal air exchange rate but also many other factors, such as the airflow pattern the space, location of contaminant sources, and properties of the contaminants. It is the objective of the present study to investigate numerically the effect of airflow patterns due to the various factors of ventilation effectiveness.

Numerical prediction of airflow patterns and ventilation effectiveness in an open office environment.

Numerical modelling is performed to predict air movement, thermal comfort level and contamination distribution within an open office space. The office located in the building interior has a concentrated thermal load at its center and is conditioned by cool air delivered from a ceiling-mounted linear diffuser. the air velocity and temperature distributions and contaminant dispersion in the office are calculated for three different cooling loads and air exchange rates with a three-dimensional turbulent finite difference model.

Evaluation of measured and computer test case results from Annex 20, Subtask 1.

The ability to accurately predict air movement and temperature distribution in spaces offers the potential for design engineers to evaluate and optimise room air distribution systems at an early stage, leading to improved thermal comfort and ventilation effectiveness. The computer models which are used for detailed analyses are based on computational fluid dynamics [1,2] and employ sophisticated numerical algorithms to satisfy the basic laws of physics. The programs are such that they are more complex and more difficult to use than those with which design engineers may be more familiar.

Field measurements of ventilation and ventilation effectiveness in an office/library building.

Mechanical ventilation system performance involves the provision of adequate amounts of outdoor air, uniform distribution of ventilation air within the occupied space, and the maintenance of thermal comfort. Standardized measurement techniques exist to evaluate thermal comfort and air exchange rates in mechanically ventilated buildings; field techniques to evaluate air distribution or ventilation effectiveness are still being developed. This paper presents field measurements of air exchange rates and ventilation effectiveness in an officepibra-y building in Washington, DC.

Pages