Department of Mathematics

Herman Miller Inc.

Proposed Project for the MSU Industrial Math Students

Space Utilization Measurement of Commercial Office Buildings


Most companies require physical space for their operations, such as to house their employees, manufacturing operations and/or inventory. The costs of acquiring and maintaining space can be significant, especially for large or disperse organizations with a large work force. Further, those needs may be dynamic, changing based on business cycles, economic or environmental factors, etc. Accordingly, it is important that space be utilized efficiently to realize both direct and indirect savings, such as lower real estate costs, utility costs, taxes, etc. For example, a company which owns two buildings capable of housing 1000 employees each may be incurring unnecessary costs if each building is actually only be utilized by 500 employees at any given time. In this case, it may make sense for the company to consolidate to one building or downsize to eliminate excess capacity, and thereby lower costs. Unfortunately, space utilization is dynamic and varies over time making the measurement of utilization difficult. Work schedules, business cycles, productions schedules, holidays and other extraneous events all combine to cause fluctuations in utilization. Therefore, to understand utilization of a space, once needs to monitor, measure and analyze utilization over time.

Herman Miller Inc (HMI) has developed the Echo System to monitor, measure and analyze space utilization at customer sites. The Echo System comprises Sensor Motes, Smart Receivers, the DCS (Data Collection Server) and the Dashboard.

  • Sensor Motes are mounted on chairs at the customer facility; the Sensor Motes sense motion, determine the likelihood that the motion corresponds to human occupancy of the chair, calculate an occupancy score every 10 minutes based on this likelihood, and wirelessly transmit this occupancy score.
  • Smart Receivers are deployed at the customer facility within range of the Sensor Motes; Smart Receivers receive the Sensor Mote occupancy scores and forward them to the Herman Miller DCS via the Internet or cellular network.
  • The DCS stores occupancy data in a database for later analysis and reporting.

  • The Dashboard monitors the health of a customer deployment, alerting the system administrator if Sensor Motes or Smart Receivers stop transmitting or report errors.

The Echo System is used by HMI to provide a Space Utilization Service to its customers. To perform a Space Utilization Study, HMI works with a customer to identify the spaces – drawn from customer floor plans – to be monitored. The Echo System is deployed at customer sites on a temporary basis, typically 3 weeks, to provide a utilization snapshot. Spaces monitored include conference rooms, workstations in open plan work environments, and/or other customer-designated spaces.

Project Description:

  • What is the relationship between the length of a study and the statistical significance of the occupancy data? What is the statistical significance by length of study? What is the optimal study length? Minimum study length? What should our statistical significance target be?
  • What customer spaces should be monitored? Do all spaces in a facility need to be monitored – or can a subset be used to estimate utilization with statistically significant results?
  • Sensor accuracy – how many different subjects, types of chairs and sensors should be included in a laboratory study to compute a statistically significant value for sensor accuracy?
  • How do sensor accuracy (percentage of time the occupancy state reported by a sensor mote agrees with true occupancy) and the reporting interval affect our overall system accuracy claims? What system accuracy claims can we make assuming 95% sensor accuracy and 10 minute reporting?

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