Indoor temperature is one of the fundamental characteristics of the indoor environment. It can be controlled with a degree of accuracy dependent on the building and its HVAC system. The purpose of this study was to evaluate the potential benefits of improved temperature control and apply the information to a cost-benefit analysis. The indoor temperature affects several human responses, including thermal comfort, perceived air quality, symptoms of sick building syndrome, and performance at work. In this study, we focused on the effects of temperature on performance at work. We collected and analyzed the literature that related performance at work to temperature. The results of multiple studies are relatively consistent, showing an average relationship of a 2% decrement in work performance per °C (1.1% per °F) when the temperature is above 25°C (77°F). Fewer data were available on performance in low temperatures. However, studies show a strong effect on manual tasks with temperatures below thermal neutrality as soon as hand temperature decreases due to control of the flow of blood. When the estimated productivity decrement from raised temperatures was applied to data from a study of nighttime ventilative cooling, the estimated value of productivity improvements were 32 to 120 times greater than the cost of energy to run fans during the night.