UBC Graduate Research

CIRS Auditorium ventilation system : adequacy assessment, energy consumption and comfort of the living space provided Tabet, Marc


The project has several purposes that will be further elaborated along the report, but mainly, providing an insight on an innovative ventilation system and the usefulness of the numerous sensors/controls its is equipped with; as well as to shed the light on how these can be used to reduce the system's energy consumption while not hindering its adequate function. a) Project Structure The first part of the project consists of thoroughly understanding and describing the system (both ventilated and ventilating) through the different sections provided and supported by numerous appendices. The second part investigates the theory behind comfortable living conditions at two levels (thermal comfort and air quality) and how it can be measured through the available sensors. The third part aims at establishing a relevant testing protocol that will make use of the different controls available in the system to try to achieve some energy savings through behavior modification. The fourth part consist in executing the protocol and extract the data from the relevant sensors. The fifth part consist of processing and analyzing the data in order to establish a relation between energy consumption and comfortable living conditions provided by the ventilation system using different tools and engineering knowledge. Finally, the different parts of the analysis are integrated in order to support suggestions about potential energy measures. Along the project a set of 6 experiments compared to a reference day were performed and their results analyzed. b) Important Findings • In comparison to other commonly found building's ventilation system the availability and variety of the sensors can be deemed excellent. • A relative humidity and temperature sensors should be installed at the exit of AHU1. • A relative humidity sensor should be installed at the level of the 1st filter of the Heat Recovery Unit. • To Date The OA and EA Flow Sensors are Uncalibrated, Insure the devices are properly calibrated in the future. • The heating valve position sensor does not seem to be reliable an investigations is recommended to shed light on the matter. • Following Ashrae 62 Standards, the outside air requirement for a maximum occupancy of the auditorium is calculated to be 3408 L/s. • Three methodologies were relied upon to verify if this criterion is met (Manual Measurements in substitution for the OA sensor - CO2 Equilibrium Methodology - CO2 Decay Monitoring Methodology). • The Manual Measurements were not reliable due to the lack of ability to perform measurements according to standardized protocols. • The CO2 decay monitoring methodology was not reliable due to the very short period of time of testing however both the methodology and the results were presented as reference for potential other studies. • The CO2 equilibrium despite inconsistencies for two experiments showed that the Fresh air intake requirement criterion is met. • When it comes to comparing the experiments to a normal day of operation such as on March 19 it is noticed that in all experiments during which energy saving measures were implemented, the ventilation system's average power consumption is indeed lower. • The energy recovered from the EA of AHU2 at the level of the HRU could not be calculated due to the absence of a proper real time monitoring of the EA flow (uncalibrated sensor). • No standards have been set for VOCs in non industrial settings. In fact, a recent review concluded that no scientifically valid guidance could be given with respect to indoor TVOC levels. There are, however, possible benefits to be derived from keeping exposures to airborne contaminants “As Low As Reasonably Achievable.” • The VOCs concentration seems unexpectedly independent of the auditorium occupation level during the testing period. An investigation should be made to explain the situation. • Critical Levels of VOCs concentration are never reached when the auditorium is occupied. • VOCs levels are pretty stable along the day, no significant fluctuations are recorded. • A VOCs concentration surge is recorded everyday during the start-up of the ventilation system that last for one to two hours. Potential exposure of students to above the critical limit of VOC concentration can occur at this moment but is not necessarily dangerous/problematic. • The critical CO2 concentration for the auditorium is considered to be 1000 ppm. This arbitrary value comes from the wide belief in building management that this is a common practice supported by Ashrae. The CO2 level of 1000 is a guideline for comfort acceptability, not a ceiling value for air quality, it is used as a surrogate for odor causing compounds from human activity that may not be acceptable for human comfort. • A narrow definition of thermal comfort was adopted, an analysis based on this criterion shows that thermal comfort is achieved within the auditorium (despite slight deviations) but overall it would be recommended to increase the temperature set point by 1 degree Celsius. • The integration of all the results obtained in this study show that, a lower energy consumption is achieved, when implementing measures through an override of the control system (such as OA intake reduction or circulation flow reduction), in comparison to a normal day of operation. Some of these measures do not affect significantly the livability of the environment which proves that there is still margin of optimizing the ventilation system operation. • Tweaking the control algorithm of the ventilation system in a way to obtain 10% less circulation flow is recommended. This measure will not hinder the livability/comfort of the auditorium's environment. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

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