Demand controlled ventilation for improving energy and environmental performance

Pao Yue-kong Library Electronic Theses Database

Demand controlled ventilation for improving energy and environmental performance

 

Author: Li, Xinhui
Title: Demand controlled ventilation for improving energy and environmental performance
Degree: M.Eng.
Year: 2006
Subject: Hong Kong Polytechnic University -- Dissertations.
Ventilation.
Indoor air pollution.
Energy consumption.
Energy conservation.
Department: Dept. of Building Services Engineering
Pages: xiv, 116 leaves : ill. (chiefly col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1973673
URI: http://theses.lib.polyu.edu.hk/handle/200/4291
Abstract: Supply CO2-based demand controlled ventilation (S-CO2-DCV) strategy maintains the supply CO2 concentration at a set-point. This strategy is usually applied to the multiple spaces subject to variable occupancy. It settles the set-point considering the full occupancy in the critical zone, Indoor air quality (IAQ) requirement can be satisfied for all the spaces, but extra energy consumption always exists in this control system due to over-ventilation in non-critical zones. In order to improve the energy and environmental performance of this strategy, the optimized set-point control is studied and improved. The improved strategy which called supply CO2 concentration optimized set-point control strategy is presented in this dissertation. This study uses the simulation program which is called Transient System Simulation Program (TRNSYS) to evaluate energy and environmental performance of the improved strategy. The component models required for simulation calculations, such as the building, air handling unit, VAV terminals, sensor, fan, damper, valve, and local and supervisory control loops, are developed and validated against the monitored data. The supply CO2 concentration set-point of the improved strategy could be determined by the monitored zone air flow rates and monitored zone CO2 concentration. It is tested and evaluated by making comparisons with other strategies. Test results indicate that the IAQ and energy consumption are significantly affected by supply CO2 concentration set-point. Supply CO2 concentration optimized set-point control strategy can achieve the tradeoff between the IAQ and energy consumption. This is because the improved strategy takes into account building actual occupancy, critical zone ventilation requirement and critical zone variations in different time. The simulation in this study was conducted based on a cloudy summer test condition. Further study can take into consideration other test conditions of different seasons.

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