This year marks the 25th anniversary of the publication of a seminal paper from Rocky Mountain Institute, “Greening the Building and the Bottom Line,” in which authors Joseph Romm and Bill Browning make the case that green buildings not only save energy and resources, but that their unique features may also improve the productivity of the employees who inhabit them. The paper described eight case studies, based on RMI studies and other articles, and quickly made an impression among sustainable design advocates. The paper was one of the first to frame the benefits of green buildings in terms of energy, rent and employee salaries on a square-foot basis. Now known as the “3-30-300 rule,” this suggests that a one-percent improvement in employee productivity may roughly equal a company’s annual energy cost for buildings.

The prospect of improved productivity quickly became a rallying cry for green building advocates, who believed that business leaders less interested in ecological concerns would pay greater attention to financial incentives. In the intervening decades, numerous researchers and industry professionals have worked to investigate, and attempted to measure, how buildings and workplaces impact our productivity.

While most studies focus on one or more variables, some have attempted to demonstrate in broad terms the financial benefits of green or high-performance buildings. A recent meta-analysis was published by stok, a real-estate services provider with offices in San Francisco and Denver. The authors reviewed over 60 studies that found productivity improvements due to air quality, ventilation, thermal comfort, biophilia/views, acoustics and ‘combined design elements,’ (the studies are conveniently summarized in the report appendix table). The authors estimate that benefits mainly from productivity and retention — with smaller benefits from wellness, energy efficiency and reduced maintenance — are worth $3000 per employee, or $18/ft2 annually.

Several studies conducted by CBE and our research affiliates have contributed to our collective understanding of workplace productivity, and this continues to be an area of interest to us and CBE’s industry consortium partners. It has been a few years since we wrote about productivity research completed or underway at CBE, so in this post we highlight newer work related to productivity, with a focus on a few key variables that are central to CBE’s research.

Hot, Cold or Just Right?

Thermal comfort has been a focus of numerous productivity studies, perhaps because temperature is readily measured, it is the most common source of workplace complaints, and it would seem to be a factor that would be easily mitigated when problems are identified (or so one might think). Using CBE’s occupant survey results in aggregate, CBE analyzed survey results from 50,000 office workers, looking at the parameters that most influenced self-estimated job performance, asking participants whether workplace characteristics ‘enhanced or interfered’ with their work. The study found that temperature had the largest influence, followed by noise level, air quality, building maintenance and visual comfort.

However, the traditional approach to thermal comfort — maintaining a narrow range of indoor temperatures temperatures  — has proven to be ineffective, as people’s preferences are highly variable, and as a result few buildings meet the industry guideline of providing comfort for 80% of a building’s occupants. Much of CBE’s recent work support an evolving paradigm for thermal comfort, to allow for a wider range of room temperatures (yielding energy savings) while giving people individualized control of comfort.

Additional support for allowing wider temperature ranges is found in a recent paper by CBE collaborators and others (subscription required).  The authors suggest that there is no single optimal temperature for all, as the neutral temperature for individuals varies greatly. They suggest that worker performance will be consistent across a range of temperatures, described by an upside-down “extended-U” shape, and that work performance only falls when conditions are outside of fairly broad parameters.

Industry practitioners have asked whether some advanced HVAC systems are better at providing comfort, and thus improve employee performance. As part of a CBE’s multi-year study of radiant systems, a literature review found three papers that showed improved comfort with these systems, and five studies that showed no difference. Again using the CBE occupant survey tools, the research team found that temperature satisfaction responses were nominally higher in the radiant buildings, but that the difference was not statistically significant. Differences between buildings is much greater than between the averages for various systems, suggesting that other factors are in play.

Indoor Air Quality: Breaking the CO2 Bubble

How air quality may affect our ability to think and make decisions is the focus of a recent article, ‘Is Conference Room Air Making You Dumber?’ Author Veronique Greenwood cites recent papers that have documented the effects on cognition, including decision-making performance, from increased levels of carbon dioxide. While results are not fully consistent, several suggest that performance in office environments suffers with high concentrations of CO2.

Because CO2 concentrations are important, ventilation rates are prescribed in codes and standards. However, CO2 levels are measured infrequently, and sensors may be unreliable. Furthermore, new research by CBE and several collaborators, with funding from the U.S. General Services Administration, shows that measured CO2 concentrations may greatly underestimate what people actually experience, as we are likely to be surrounded by a CO2  ‘bubble’ of our own making when we are seated and sedentary at a desk. Luckily a solution is simple: the study also found that small desk fans can effectively ‘burst the bubble’ and reduce the CO2 we experience. When considering monetary impacts from productivity gains, an inexpensive desk fan may have a payback of just a few days.

Can you Hear Me Now? Acoustics and the Open Workspace

Numerous articles and this blog have described the conflicting desires for increasing  interaction versus the need some people have for interruption-free spaces. At CBE’s membership meeting last April, Research Specialist Lindsay Graham presented preliminary results from a new survey to understand how individual differences impact acoustical experiences in open plan spaces, and what people do to mitigate acoustic problems when they arise. This work, being done with support from Perkins+Will HxLab and  Charles M. Salter Associates, is showing that some individuals are more sensitive to distracting sounds, and that design solutions need to provide resources those individuals to help them improve focus when needed. Potential solutions include providing headsets for phone calls, and noise-cancelling headsets for providing an acoustical space (and providing a do-not-disturb signal to coworkers). These solutions were viewed as useful by over 70% of employees surveyed in a field study CBE conducted at a large technology firm. Results are forthcoming later this year.

New Research Directions: How View Quality Impacts Comfort, Cognition and Mood

An emerging body of research shows that connections to nature can provide numerous benefits in terms of health, happiness and cognition. Design following the principles of biophilia has become common, and CBE is now working with CBE partners from SERA Architects to develop new occupant and building survey metrics to investigate how these strategies are working.

A new project by PhD candidate Won Hee Ko and Associate Professor Stefano Schiavon is investigating the impact of views on cognitive performance, mood and creativity. Using CBE’s controlled environmental chamber, subjects were placed in rooms with or without windows, where they took cognitive tests and responded to surveys. Preliminary results show that windows improved subjects’ positive emotions, as one might expect. The cognitive test results are being analyzed and results will be presented at CBE’s October meeting. The next step will be the development of a view access index that will allow designers to predict the effect of view access in building designs, possibly using virtual reality headsets to evaluate the perception of spaces with windows. This work builds on previous work to create a combined method to analyze daylight, thermal and ventilation autonomy.

Finally, our research team is looking at using new technologies to study how the indoor environment effects worker cognition and performance. In collaboration with collaborators at SinBerBEST, we are developing new methods to use eye tracking devices, which allow us to study eye movement and pupil size as an indicator for task demand. We are also looking into the use of bio markers such as CO2 and heart rate, to further advance this important work.

Featured image: The Rocky Mountain Institute (RMI) Innovation Center was a Livable Building Award winner in 2018. Learn more >

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