Human Performance

The performance of office and school work is affected by indoor environmental conditions and by the features of buildings that influence indoor environmental conditions. Work performance may be improved from a few percent to possibly as much as 10% by providing superior indoor environmental quality (IEQ). The economic benefits of the work performance improvements will often far outweigh the costs of providing better IEQ. The main findings of related scientific research are as follows:

Temperature and Office Work Performance

A majority of studies indicate that performance (speed and accuracy) of office work tasks is affected by air temperature or the associated level of thermal comfort, with performance usually highest when the air temperature maximizes comfort. For most U.S. and European office conditions, work performance and thermal comfort is highest at approximately 71 °F or 72 °F. As the indoor air temperature rises above or falls below this range, performance decreases on average, by 0.3% to 0.4% per each 1 °F change in temperature. Temperature changes when the temperature is near the optimum temperature have a smaller impact on performance. Some studies indicate improvements in performance when temperatures increase above 71 or 72 °F, particularly when higher temperatures improve thermal comfort. Also, there are a significant number of studies that failed to find an impact of temperature on work performance. The impact of temperature or thermal comfort on work performance may depend on the type of work and the level of the workers' motivation.

Temperature and School Work Performance

In a high quality experimental study, the average speed of completing academic work, based on monitoring of performance of eight simulated school work tasks, decreased by approximately 1.1% per each 1 °F as temperatures increased from 68 °F to 77 °F. The number of errors in school work was not significantly affected by temperature changes in this temperature range.

Ventilation Rates and Office Work Performance

Performance (speed and accuracy) of typical office tasks improves with increased ventilation rate. For initial ventilation rates between 14 and 30 cfm per person, the average performance increases by approximately 0.8% per 10 cfm per person increase in ventilation rate. At higher ventilation rates, the average performance increase is smaller, approximately 0.3% per 10 cfm per person increase in ventilation rate. For ventilation rates less than 14 cfm per person, performance increases with ventilation rate seem likely; however, sufficient data are not yet available to confirm this hypothesis.

Ventilation and School Performance

Based on a substantial body of research, ventilation rates in classrooms often fail to meet minimum standards. Also, increases in classroom ventilation rates up to approximately 15 cfm (7.1 L/s) per student are associated with improvements in student performance of a few to several percent, with the magnitude of improvement depending on the initial ventilation rate.

Indoor Pollutant Sources and Work Performance

A few laboratory and field studies have measured approximately 4% to 16% increases in the performance (speed or accuracy) of selected office work tasks [e.g., typing, addition errors (in one study), speed of call center work] when indoor pollutant sources were removed, while performance of other tasks (e.g., proof-reading, creative thinking) was not significantly affected by source removal. One laboratory study reported an average 60% increase in scores in decision making performance with low indoor sources of volatile organic compounds typical of green office buildings relative to sources of volatile organic compounds typical of conventional office buildings. The magnitude of performance improvements from pollutant source removal or exclusion is likely to depend highly on the source characteristics and building ventilation rate.

Perceived Indoor Air Quality and Performance

Better perceived indoor air quality is correlated with improvements in office work tasks, with approximately a 1% increase in task performance per each 10% decrease in the percentage of occupants dissatisfied with indoor air quality. However, it is not known whether poorer perceived air quality causes a reduction in work performance or is simply correlated with performance because the same indoor environmental conditions affect both performance and perceived air quality.

Daylight, View, and School and Work Performance

There is some evidence that more daylight or a view to outdoors improves office and school work performance, but the available data are limited and findings are inconsistent.

Lighting Levels, Lighting Quality, and Work Performance

Available data are too limited to draw conclusions about the impacts of typical changes in indoor lighting levels and lighting quality on performance of office and school work. Significant impacts on performance are most likely for subjects with poor or uncorrected vision.

Cost Effectiveness of Improving Indoor Environments to Increase Productivity

Large paybacks can be expected from many changes in building design, operation, and maintenance that improve worker performance because worker salaries and benefits greatly exceed the costs of providing and operating buildings. Example cost-benefit analyses indicate that benefits may often exceed costs by a factor of 10 or more.