Pilot Study for the Performance of a New Demand Control Ventilation System in Hong Kong
Publication: Journal of Architectural Engineering
Volume 11, Issue 3
Abstract
There are different ventilation control methods for outdoor air quantity in air-conditioned spaces to reduce the energy consumed in cooling the outdoor air. Demand controlled ventilation (DCV) is an important strategy to control the outdoor air quantity. However, the current practice in DCV systems creates several problems for air-conditioned office buildings. Although metabolic carbon dioxide concentration is mainly used as a surrogate indicator for ventilation adequacy, the conventional DCV system does not seriously consider the placement location of the sensor, and it does not take into account the adverse effects of the consequential increase in pollutant concentrations in the indoor space when the fresh airflow rate is reduced. In this study, a long period of subjective and objective measurements were conducted in an occupied office to examine its suitability for conversion to a new demand controlled ventilation system (nDCV). After the feasibility investigation, an nDCV system was developed to optimize the energy consumed for outdoor air ventilation while providing the desirable thermal comfort and indoor air quality. The true optimization of this nDCV is achieved by a new concept of the optimized indoor air quality window which determines the most representative locations for the indicator sensors. A minimum ventilation rate is determined by a calibration procedure for the pollutant inventory of a building, taking into account the infiltration characteristics. Radon gas, which is a notorious carcinogenic indoor pollutant, is used as a reference to determine the minimum fresh airflow rate. The findings show that this nDCV system reduced 16% of fresh air cooling energy consumption without jeopardizing the thermal comfort and indoor air quality.
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Acknowledgments
This paper arises out of work undertaken in the Department of Building Services Engineering, The Hong Kong Polytechnic University. Funding has been received from the Research Grants Council and from internal grants from The Hong Kong Polytechnic University (A-PG41).
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Information
Published In
Journal of Architectural Engineering
Volume 11 • Issue 3 • September 2005
Pages: 110 - 115
Copyright
© 2005 ASCE.
History
Received: Oct 7, 2003
Accepted: Jan 14, 2005
Published online: Sep 1, 2005
Published in print: Sep 2005
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