Comparison of Employees’ Satisfaction with Indoor Environmental Quality: Post-Occupancy Evaluation 2011 and 2014

Presented by: Lead Author: Maureen Soules, CID, IIDA, IDEC; 2nd Author: Denise Guerin, PhD; 3rd Author: Theresa Bauer, MA

Overview: Connections between sustainable design criteria used in a Midwestern university classroom/office building and employees’ satisfaction with their work environment were examined. The building used a set of state-mandated sustainable design guidelines and met LEED New Construction Version 2.2 Gold Certification. It was completed for occupancy Fall 2010. The Sustainable Post-Occupancy Evaluation Survey (SPOES) was developed to assess human outcomes in classroom and workplace settings in compliance with the project tracking requirements. This presentation compares occupants’ responses at one year (2011) and four years (2014) post-occupancy. 

Method: SPOES is a self-administered, Internet-based questionnaire submitted to and completed by occupants/employees. It has been tested for validity and reliability in studies involving similar facilities and employees. Employees rate their level of satisfaction on a Likert-type scale from 1 (very dissatisfied) to 7 (very satisfied) with indoor environmental quality (IEQ) of the facility (site, building, and interior) and their primary workspaces. They also rate the influence of their physical environment on their perception of their work performance and health on a scale from 1 (hinders) to 7 (enhances). This presentation provides a statistical comparison of employees’ satisfaction with their primary workspaces and IEQ Score between the two occupancy periods.  Factor analysis was used to calculate the IEQ Score for primary workspaces.

Sample Description: Built in 2010, the five-story, 118,000 square-feet building houses instructional classrooms and administrative offices that service the university’s students, faculty, and staff. There was a response rate of 75% (N=79) in 2011 and 53% (N=51) in 2014. 

Findings and discussion:  Employees responded to questions concerning their satisfaction with the facility (site, building, and interior); their primary workspaces; and perceptions of their work performance and health in relation to the facility. Table 1 (see Appendix A) shows a summary comparison and interpretation of their responses. Employees rated their satisfaction with the physical environment for 14 IEQ criteria including: acoustic conditions, appearance, cleaning and maintenance, daylighting conditions, electric light conditions, function, furnishings, indoor air quality, personal adjustability conditions, privacy, technology, thermal conditions, vibration and movement, and view conditions, related to their primary workspace.Table 2 shows a summary comparison and interpretation of their responses. Table 3 shows the F-test for variance of the IEQ scores between 2011 and 2014 and the variances are not equal. Using these data, a t-test on the means was performed and is shown in Table 4.  The paired t-test for two-sample means indicates a significant decrease in overall satisfaction with a P score less than 0.05.

An IEQ satisfaction score was determined by using factor analysis to develop weighted factors for all criteria.  A factor analysis provides a single IEQ score that combines and weights all the criteria; it also calculates the relative importance of each criteria to the whole IEQ score.  In 2011, the IEQ score was 5.07 and in 2014 the score was 5.00, again indicating a decrease in satisfaction.

Conclusions: The satisfaction scores between the two studies are mixed and more than half the criteria are moving in a negative direction, however, improvement may be possible. Attention should be given to criteria where scores declined from 2011 to 2014. This study investigated employees’ satisfaction with the facility and primary workspaces. The results can be used as a diagnostic tool to aid in improving IEQ conditions for employees and to set the benchmarks from which improvement can be measured in the future.


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