Analysis and Prediction Techniques

In large enclosures, common ventilation strategies, as complete mixing, require considerable amounts of energy to move and condition enormous amounts of air. The air flow pattern should therefore be well planned and controlled to ensure an acceptable indoor air quality in the occupied zone without the need for excessive air flow rates. This part of the summary report concentrates on describing methods for designing and analysing ventilation in large enclosures. lt includes application of different mathematical models in the design process for simulation of temperature distribution, air motion and contaminant spread in order to evaluate performance and locate problems. At the first stages of the design process information is rather limited. Approximate HVAC solutions are developed based on engineering experience and use of appropriately simple analytical tools (macroscopic models) to save design work. At the latter stages of the design process more information is available and more detailed analytical tools (microscopic models) can be applied to evaluate the proposed air flow design. The Annex 26 work has resulted in an easy and strategic procedure for designers and HVAC engineers to design ventilation and air conditioning by choosing adequate models at each design stage.