Measurements of ventilation rates and ventilation effectiveness

Describes how multizone tracer gas analysis techniques can provide a complete description of office ventilation. Treats the concept of ventilation effectiveness to characterise internal air distribution. Discusses the measurement of whole building ventilation rates and ventilation effectiveness in mechanically ventilated office buildings.

Air flow in buildings. Luftstromning i byggnader.

Outlines the principles of air flow in buildings: the driving forces of wind and thermal pressure; laminar and turbulent flow; and the effects of the building geometry. Reviews the existing mathematical models of air flow and provides worked examples for a house and a multi-storey building.

Natural ventilation between two adjacent rooms. Ventilation naturelle entre deux pieces d'habitat.

This study deals with natural heat transfer through apertures between two adjacent rooms. A one-dimensional model has been developed to determine the flow rate and enthalpy rate transferred through each aperture as well as the vertical temperature profile in each room. Results show that flow rate and enthalpy rate vary quasilinearly through time. Temperature profiles show a high thermal stratification depending on the relative location of the apertures. Experiments have been performed in a test apparatus using water. Temperatures have been measured.

Computation of ventilation currents.

Much research work has been carried out on modelling ventilation air currents. The authors propose that the currents be divided into specific zones, the air parameters of each zone being determined by different conditions. The formula is then derived by the addition of an infinite number of elementary currents flowing from a multitude of point sources. From this, a general formula is proposed to calculate the velocity, temperature and admixture concentration along the whole flow of the current.

The use of a constant concentration tracer gas system to measure ventilation in buildings.

A constant concentration tracer gas system was designed and constructed to continuously measure the air infiltration rate in as many as ten zones of a building. The portable, microcomputer controlled system injects a metered amount of tracer


A comprehensive computer program for the prediction of air flow and smoke migration in the building was applied to the 11 story administration building of the National Bureau of Standards. Natural air leakage rates under various climatic conditions for several ventilation system operations were obtained. The computed results were compared with measured air leakage rate by using the sulphur hexafluoride tracer gas technique. Smoke migration was simulated for the selected pressurization conditions.