Control of Outdoor Ventilation Airflow Rate - Evaluation of Setting Methods

Ventilation is essential for the health and comfort of building occupants. It is particularly required to dilute and/or remove pollutants emitted by occupants' metabolism and activities. The concentration of metabolic CO2 is well correlated to metabolic odour intensity. Therefore CO2 concentration can be efficiently chosen as an indoor air quality index when occupants are the main source of pollution inside the buildings. This paper presents details of the research conducted in order to adjust and compare five advanced techniques based on CO2 level measurement in order to adapt ventilation extractor fan speed to the intermittent occupation of an office. An experimental device (HybCell one-zone test cell) was chosen to compare these five control technologies (i.e. on/off, proportional integrative regulator, fuzzy logic control, analytical control function and radio frequency identification) under the same experimental conditions. A method was developed to define the setting parameters of a proportional integrative and a fuzzy logic control regulator of an extract fan. Criteria based on control precision, command stability and global air exchanged were then established for the final evaluation. The results revealed fine control accuracy. They showed a good stability with a reduced and simplified setting period for the developed methods compared to current controllers.