Technical Note
2 total works
v. 11/95
Natural ventilation has the potential to replace or supplement air conditioning, comfort cooling and mechanical ventilation. Whilst there are obvious environmental advantages, there are problems to achieving adequate control as the flow of air must be controlled to limit energy consumption and maximize thermal comfort. This "Technical Note" provides guidance on the application of BMS (Building Management System) controls to natural ventilation. The use of automatic controls is not a panacea for ventilation problems. A vent under occupant control should generally be provided, thus allowing the building occupants to manipulate their own environment. However, the provision of automatic control of air inlet vents and inaccessible air outlet vents results in improved ventilation rates, particularly in the summer, thus enhancing the working environment. Further to this, automatic controls offer the opportunity for night cooling techniques, thus helping to ameliorate daytime heat gains.
This publication presents a number of generic control strategies for natural ventilation, mixed-mode ventilation and night cooling, which are used to control this enhanced daytime ventilation and night cooling. Procedures for commissioning and fine-tuning buildings using these strategies are described, together with appropriate control setpoints. An analysis of the costs of buildings utlizing various ventilation types is also provided. The guidance is reinforced with the results of monitoring carried out in three naturally ventilated buildings. A description of the buildings is presented, together with details of the control strategies and the results of monitoring. General conclusions regarding the control strategies and the performance of the ventilation system in each of the buildings is presented. Finally, a description and details of the control strategies of eight further buildings utilizing controlled natural ventilation are presented.
This publication presents a number of generic control strategies for natural ventilation, mixed-mode ventilation and night cooling, which are used to control this enhanced daytime ventilation and night cooling. Procedures for commissioning and fine-tuning buildings using these strategies are described, together with appropriate control setpoints. An analysis of the costs of buildings utlizing various ventilation types is also provided. The guidance is reinforced with the results of monitoring carried out in three naturally ventilated buildings. A description of the buildings is presented, together with details of the control strategies and the results of monitoring. General conclusions regarding the control strategies and the performance of the ventilation system in each of the buildings is presented. Finally, a description and details of the control strategies of eight further buildings utilizing controlled natural ventilation are presented.
TN 1/96
Demand-controlled ventilation systems can be used to minimize energy consumption whilst maintaining satisfactory levels of indoor air quality (IAQ). As an alternative to CO2 sensors, IAQ sensors (based on Taguchi mixed-gas sensors) can be used to infer levels of IAQ. This "Technical Note" provides details of a series of laboratory and site tests to determine the performance of a range of indoor air quality (IAQ) sensors. As part of laboratory tests, the IAQ sensors demonstrated relatively high correlation co-efficients when tested against pollutants, however, co-efficients corresponding to test data over periods when the sensors were subjected to non-controlled conditions (for example, a wide range of non-controlled pollutants) demonstrated a poor relationship when there was no single predominant pollutant. Site monitoring in three buildings demonstrated relatively poor correlation co-efficients between the IAQ sensors and monitored gases due to the unquantifiable presence of other pollutants. The strongest correlations between IAQ sensors and pollutant gases were obtained when a pollutant gas was present in a sufficient concentration to pervade the complete atmosphere of a zone.
The site monitoring demonstrated that the dilution of pollutants in the indoor environment may be carried out at the expense of introducing polluted air from the outside. A major source of pollution to affect the monitored sites was from vehicle traffic (indicated by levels of CO). The use of CO2-controlled ventilation techniques is more effective than IAQ sensors in applications where IAQ is primarily influenced by varying occupancy.
The site monitoring demonstrated that the dilution of pollutants in the indoor environment may be carried out at the expense of introducing polluted air from the outside. A major source of pollution to affect the monitored sites was from vehicle traffic (indicated by levels of CO). The use of CO2-controlled ventilation techniques is more effective than IAQ sensors in applications where IAQ is primarily influenced by varying occupancy.