Building Science at UC Berkeley: Research

A Field Study of PEM Performance in Bank of America’s
San Francisco Office Buildings

Edward Arens, Department of Architecture
Fred Bauman, Center for Environmental Design Research

Johnson Controls World Services, Inc.

A field study was carried out to assess the impact of installing Personal Environmental Modules (PEMs), a commercially available desktop task/ambient conditioning (TAC) system, at 42 selected workstations within three Bank of America office buildings in San Francisco. The PEM is an example of a relatively new approach to space conditioning and control in which individuals are given the ability to control critical environmental conditions within their local work area (e.g., workstation). Each office worker can adjust air flow, temperature, lighting, and acoustic characteristics to maintain their own personal comfort levels. By improving employee satisfaction and well-being, it is anticipated that the installation of a PEM system could lead to increased worker productivity and effectiveness.

In this study, field measurements, including subjective surveys and physical monitoring, were performed both before and after the PEM installation to evaluate the impact of the PEM system on occupant satisfaction and thermal comfort, as well as the thermal environments within the office buildings. For comparative purposes within each building, a control group, consisting of workers who did not receive a PEM unit, was studied concurrently. The first baseline field measurements were made in March 1996. The 42 PEM units were installed in the three buildings during the first two weeks of April. During the follow-up field tests, performed three months after the PEM system installation, measurements were repeated under three different room temperature setpoint conditions (normal, set-up, and set-down) to investigate the occupants’ ability to use the PEM units to control their local environment in response to a wider range of ambient temperatures.

The survey results show that among the six building assessment categories investigated (spatial layout, office furnishings, thermal comfort, air quality, lighting quality, and acoustical quality), installation of the PEM system provided the largest increases in overall occupant satisfaction for thermal comfort, acoustical quality, and air quality. In terms of specific environmental factors, increased occupant satisfaction levels among the PEM group were strongly significant in comparison to changes within the control group for both temperature and temperature control. A large majority of the workers in the control group indicated a preference for higher air movement at operative temperatures of 73° F (23° C) and above. The percentage preferring higher air movement within the PEM group was significantly lower. Workers in the PEM group had the ability to use their PEM units to adjust the air movement in their workstations in response to changes in the ambient temperature. Over the range of operative temperatures covered by this field study, air movement preference and thermal sensation votes by workers in the control group indicated that they were more than twice as sensitive to changes in temperature as those in the PEM group

This project provided support for two Masters students.