A new room model has been developed and validated in order to be used for the assessment of HVAC sensors, assuming non-homogeneous room conditions and distinguishing between different sensor positions. .
The purpose of this report is to summarise the work of IEA Annex 18 on demand controlled ventilation. It is primarily aimed at building services practitioners, designers and policy makers who require background knowledge of the operational principles and range of applicability of this approach to ventilation. The primary focus is on applications and the conditions required for the operation of such systems. This international activity has been carried out by a working group of researchers from ten countries (Appendix 1) with Sweden bearing the main responsibility as Operating Agent.
This paper examines three different ventilation strategies aimed at reducing the indoor concentration of traffic pollutants by ventilation control. In the strategies the air change rate is adjusted in response to (a) the outdoor concentration of the pollutant (single-sensor strategy), (b) the outdoor and indoor concentration (double-sensor strategy) and (c) the time of the day (peak-period strategy). A double sensor was found to be twice as effective as the single sensor, reducing the mean indoor concentration of carbon monoxide by 34% over a 48-hour period.
With sensor-based demand-controlled ventilation ( SBDCV), the rate of ventilation is modulated over time based on the signals from indoor air pollutant or occupancy sensors. SBDCV offers two potential advantages: better control of indoor pollutant concentrations, mid lower energy use and peak energy demand.
A test room and measurement system were developed for the full-scale measurements of the active displacement air distribution. The room represents a 3-meter wide module of a larger hall. The requirements for the room included minimisation of the errors caused by air leaks, thermal conductance and flow obstacles. The measurement of the flow pattern is carried out with ultrasonic and thermal anemometers. Automated traversing system was built to move the sensors in the vertical symmetry plane of the room.