The aim was to develop a simple dynamic model for predicting air exchange caused by short time single-sided ventilation and necessary window opening time in classrooms. Tracer gas measurements have been made in a full-scale room. The comparison indicates that the model can be used when rough estimates of air exchange are of interest.
The simulation of room airing (ventilation by means of door/window opening) by means of CFD techniques requires a specially skilled user, because a number of difficulties arise since the first stage of simulations development, when the user is asked to choose the calculation domain and the time step, and choices which in principle appear correct may frequently lead to meaningless results. This work is centered on the 20, transient analysis of a single side enclosure where the ventilation is only due to temperature differences. Wind effect has not been taken into consideration.
In the design of natural ventilation systems, there is a wide range of possibilities with regard to the selection of window type and the positioning of windows in the facade. Each window type has unique characteristics, which affect air flow and thermal comfort conditions in the occupied zone. A combination of various window types and faade locations in a room should be capable of improving thermal comfort and minimising draught risk.
The homogeneous emission passive tracer gas technique is described. This technique relies on an even distribution of constant tracer gas emission rate within the object to be measured, so that the emission rate per volume unit is constant. The local steady state concentration of the tracer gas is directly proportional to the local mean age of air and the emission rate per volume unit.
Login