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Knowing the presence or the actual number of occupants in a space at any given time is essential for the effective management of various building operation functions such as security and environmental control (e.g., lighting, HVAC). As occupants "interact" with the indoor environment, they will affect environmental conditions through the emission of CO2, heat and sound, and relatively little effort has been reported in the literature on utilizing this environmental sensing data for occupancy detection. This paper presents the findings of a study to address this question by exploring the most effective environmental features for occupancy level detection. A sensor network with robust, non-intrusive sensors such as CO2, temperature, relative humidity, and acoustics is deployed in an open-plan office space. Using information theory, the physical correlation between the number of occupants and various combination of features extracted from sensor data has been studied. The results show significant correlation between features extracted from humidity, acoustics, and CO2, while little correlation with temperature data. Using features from multiple sensors increases correlation further, and nearly 90% information gain is acquired when nine of the most informative features are combined.


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Information-theoretic environment features selection for occupancy detection in open office spaces

Show Author's information Rui Zhang1( )Khee Poh Lam2Yun-Shang Chiou3Bing Dong4
IBM, T.J. Watson Research Center, Yorktown Heights, NY 10598, USA
Center for Building Performance and Diagnostics, School of Architecture, Carnegie Mellon University, Pittsburgh, PA 15213, USA
Department of Architecture, National Taiwan University of Science and Technologies, Taipei, 106 Taiwan, China
United Technologies Research Center, East Hartford, CT 06108, USA

Abstract

Knowing the presence or the actual number of occupants in a space at any given time is essential for the effective management of various building operation functions such as security and environmental control (e.g., lighting, HVAC). As occupants "interact" with the indoor environment, they will affect environmental conditions through the emission of CO2, heat and sound, and relatively little effort has been reported in the literature on utilizing this environmental sensing data for occupancy detection. This paper presents the findings of a study to address this question by exploring the most effective environmental features for occupancy level detection. A sensor network with robust, non-intrusive sensors such as CO2, temperature, relative humidity, and acoustics is deployed in an open-plan office space. Using information theory, the physical correlation between the number of occupants and various combination of features extracted from sensor data has been studied. The results show significant correlation between features extracted from humidity, acoustics, and CO2, while little correlation with temperature data. Using features from multiple sensors increases correlation further, and nearly 90% information gain is acquired when nine of the most informative features are combined.

Keywords: feature selection, occupancy detection, environmental sensor network, information theory

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Publication history
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Acknowledgements

Publication history

Received: 08 August 2011
Revised: 10 February 2012
Accepted: 27 February 2012
Published: 09 May 2012
Issue date: June 2012

Copyright

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2012

Acknowledgements

This work is supported in part by the Bosch Research and Technology Center, Pittsburgh, PA. The authors would also express sincere gratitude to Andrews Burton from Bosch Research and Technology Center for his comments and revision support on the paper.

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