Two different studies were conducted at the same organization, the Sacramento Municipal Utility District. The first study looked at 100 workers in an incoming call center, whose performance was continuously tracked by a computer system and measured in terms of time to handle each call. The second “Desktop” study examined the performance of 200 other office workers on a series of short cognitive assessment tests, taken at each individual’s desktop computer. The studies have shown that indoor environmental conditions can have a measurable relationship to changes in office worker performance and have established a range of likely effect sizes that other researchers can use to refine the needs of future studies.