How to Reduce Air Change Rates


Problem: With their critical needs for indoor air quality, power, temperature, humidity and other environmental conditions, labs traditionally have had a difficult time balancing the growing pressures for energy efficiency with the technical requirements of the required functionality within the facility. Take air quality, for example—labs often have very high air change requirements, commonly ranging anywhere from 10 to 80 changes per hour, depending on the uses of the lab. However, not all of the uses in a lab function continuously, meaning at some points, the lab may be able to decrease those air flow changes—thus saving energy in heating, cooling and fan motor horsepower—so long as the air quality remains at an acceptable level.Fan systems, air handling units, and other equipment save energy when running with air control management systems.

Solution: Some labs have begun to install air quality control and measurement systems like Aircuity to help optimize air changes as they are needed, saving energy in the process. These systems regularly monitor the lab’s air quality every few minutes, taking samples and adjusting the controls accordingly. In other words, the system can taper down or ramp up air changes depending on what it detects.

The idea is that what are now considered “standard” air change rates are often broad estimates of a prescriptive nature, while the actual needs of each lab vary widely depending on its uses. With these control and measurement systems, labs can decrease a standard air change rate of 12 times an hour to, say, 6 or even 4 as long as air quality, temperature, humidity, and other conditions are not adversely affected. For labs with high odors, fumes, and the like, that change may not be feasible.

Accordingly, because these systems monitor the constituents in the air, these systems are best suited for labs that have wide variation in airflow change characteristics and periods of time where the lab is unoccupied (e.g., while experiments are running—or simply being occupied). They can be installed and integrated with the existing HVAC fairly easily, but do require added capital costs and some planning ahead.

That planning includes determining where the lab experiences the largest variation in loads. Those areas may be good candidates for reducing the number of air changes when the air quality is stable or users aren’t present. Engineers and architects at Stantec recently helped one pharmaceutical company integrate an Aircuity system into its labs, conducting just that kind of analysis. Based on those findings, the team devised a concept of where the Aircuity sensors should go, organized both around the equipment being used and the pertinent uses. If this system works as planned in this 15,000-square-foot pilot facility, it is expected to reduce energy costs enough to pay for itself within two to three years and serve as a model for the company to expand to its other facilities.

While large-scale uses of these air management systems are still somewhat new, they have proven to have a number of general benefits. The systems, of course, help a lab use less energy and reduce its carbon footprint, but they also can improve the equipment’s longevity by operating at part load more often (and running more quietly). What’s more, incorporating these kinds of systems and lowering energy use better prepare labs for the requirements for lower energy use that are surely coming down the pipe. And with their relatively quick turnaround time for payback—in some cases, just a few months—all of these benefits add up to improved performance, reduction of the carbon footprint and significant financial savings.

For more information on installing air quality control and measurement systems, contact Joseph Masiello at Stantec at

Categories: How it Works

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Finding Dollars Magazine Issue Cover
Finding Dollars

Published: November 1, 2013

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