The primary aim of the project is to describe and document a measurement method suitable for checking whether minimum requirements for ventilation efficiency are fulfilled after a ventilation system has been regulated. The project concentrates on occupied areas with mechanical ventilation such as dwellings,offices and schools. Excludes industrial buildings since special conditions such as ventilation rates, polluting processes and local extraction apply to these. Defines ventilation efficiency, describes equipment and measurement with CO2, N2O, SF6, Kr85.
Examines various definitions of ventilation efficiency. When using tracer gas techniques the definition of a ventilation system's efficiency can be based on the slope of the tracer gas curve, or the ratio between concentrations, or the area under the curve. Examines the consequences of these definitions for a simple theoretical model. Presents experimental measurements on a test room which show that sometimes very low ventilation efficiency can occur.
Ventilation efficiency involves two aspects, to preserve thermal comfort, draughts should be avoided and yet one tries to obtain the best "sweeping out" which corresponds with a maximum exhaust of contaminants from the occupied zone for a given flow rate.< Reports study of 75 tests of ventilation efficiency made in a climatic roomrepresenting a heated living room. Thermal comfort was tested by measuring the air velocity both in the ventilation jet and in the occupied zone.
The local ventilation efficiency of a mechanical ventilation system may in general terms be defined as "providing air in those parts of a room where it is required". In this paper different definitions of the local ventilation efficiency and methods for measuring it are discussed. Presents results from measurements of ventilation efficiency. A test room was mechanically ventilated and nitrous oxide used as a tracer gas. A number of sensors were placed in the room with the aim of determining the variations in the air change rates within the room.