WASHINGTON — A new study finds that doubling the ventilation rate in typical office buildings can be reached at an estimated annual energy cost of between $14 and $40 per person, resulting in as much as a $6,500 equivalent in improved productivity per person per year. When energy-efficient technologies are utilized, the study found the energy costs to be even lower, with a minimized environmental impact of approximately 0.03 additional cars on the road per building.
The research, titled “Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings,” was conducted by the Harvard T.H. Chan School of Public Health’s Center for Health and the Global Environment, SUNY Upstate Medical, Syracuse University, and Carrier. The study was supported by United Technologies Corp. and its UTC Climate, Controls & Security business, a leading provider of HVACR systems, building controls and automation, and fire and security systems.
The report was published in the International Journal of Environmental Research and Public Health’s special issue “Indoor Environmental Quality: Exposures and Occupant Health,” and builds on the recently released “Impact of Green Building on Cognitive Function“ study by the same research team. Also known as The COGfx Study, the research found cognitive function test scores improved 101 percent in green building environments with enhanced ventilation compared to conventional building environments.
“This study shows there is no longer a tradeoff between energy efficiency and indoor environmental quality — both can be achieved together to accelerate the green building movement,” said John Mandyck, UTC chief sustainability officer. “Readily available, energy efficient technology can turn office buildings into human resource tools that improve the health and productivity of the people inside.”
Researchers studied three indoor environments achieved by four different HVAC system strategies across seven U.S. cities as outlined below. For each scenario, the team selected the U.S. Department of Energy Medium Office Prototype (a 53,000-square-foot, three-story building with more than 260 occupants) as the standard; used state average utility prices for each city; and referenced salary data obtained from the Bureau of Labor Statistics.
• Three indoor environments: standard ventilation at 20 cubic feet per minute of outdoor air per person, the green condition used during The COGfx Study; 30 percent higher ventilation than ASHRAE Standard 62.1-2010, which is required to obtain a U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED®) credit for enhanced ventilation, equivalent to 27.6 cubic feet per minute of outdoor air per person; and 40 cubic feet per minute of outdoor air per person, the enhanced green condition used during The COGfx Study.
• Four HVAC system strategies: variable air volume (VAV) and fan coil unit (FCU) systems, both mature technologies typically used in office buildings. Both systems were evaluated with and without an energy recovery ventilator (ERV), which improves system energy efficiency.
• Seven U.S. cities representative of different climate zones: Albuquerque, New Mexico; Austin, Texas; Baltimore; Boise, Idaho; Boston; Charlotte, North Carolina; and San Francisco.
The researchers used Carrier’s Hourly Analysis Program (HAP) to calculate the annual energy consumption for the HVAC equipment. Environmental impacts were then derived using the U.S. Environmental Protection Agency’s Power Profiler tool. At the highest ventilation rate, they found that adding an ERV “essentially neutralizes the environmental impact of enhanced ventilation” — equivalent to approximately 0.03 additional cars on the road per building across all cities. Specific results are dependent upon each city’s individual power generation fuel mix, with researchers noting “the per building environmental impact on greenhouse gas emissions is not as impactful as the estimated benefits.”
Mandyck noted any additional energy needed to achieve the substantial gains in productivity can be offset with lower carbon strategies achieved with green buildings. “Research like this has the potential to encourage the adoption of more green building, which means more energy can be saved over the long term,” he said.
“Three decades of research show the health benefits of increased ventilation, and now our recent research shows that these benefits extend to cognitive function, yet enhanced ventilation credits in green building certification systems are not uniformly pursued. We sought to understand potential barriers to widespread adoption,” said Dr. Joseph Allen, assistant professor of exposure assessment science, Harvard T.H. Chan School of Public Health, and director of the Healthy Buildings program at Harvard’s Center for Health and the Global Environment. “This research suggests that the health and productivity benefits far outweigh energy costs and environmental impacts can be mitigated through a variety of readily available strategies. It is time we move away from ventilation designed for merely acceptable indoor air quality and move towards design for optimal indoor air quality. We have been presented with the false choice of energy efficiency or healthy indoor environments for too long. We can — and must — have both.”
“It’s important to note that our study provides a conservative estimate of the benefits of enhanced ventilation because we focused solely on cognitive function. The public health literature indicates that we would expect many co-benefits of increasing ventilation rates, such as reduced absenteeism due to illness, which has clear impacts on productivity,” said Piers MacNaughton, doctoral candidate at the Harvard T.H. Chan School of Public Health and project manager of The COGfx Study.
“This study makes the case that new building construction should design for ventilation rates above current code-mandated levels and include ERVs, and existing buildings should investigate retrofitting with increased ventilation rates and ERVs — both to improve occupant productivity and reach building sustainability goals,” said Jim Pegues, engineering fellow and study researcher, UTC Climate, Controls & Security. “For building owners interested in replicating the analysis of energy cost and environmental impact for their own buildings, the modeling is straightforward and we believe could be used by owners for all building types.”
The full study can be found at www.thecogfxstudy.com.
For more information about UTC Climate, Controls & Security, visit www.ccs.utc.com.
Publication date: 12/1/2015