Setting the Standard: Why Sensor Calibration and Proven Design Are Vital for Healthy, Sustainable Buildings (And Some Important Questions to Ask)

Nov 1, 2024

The pandemic highlighted ventilation’s critical role in maintaining building health. Effective system design and operation, facilitated by reliable DCV solutions, are essential to optimizing health and safety while supporting sustainable operations. Yet, many building operators continue to use discrete sensors or unverified systems that lack NIST (National Institute of Standards and Technology) factory calibration—a critical component for safety and performance. Some sensors claim self-calibration, but studies like the LBNL CO2 Field Sensor Study consistently demonstrate that drift occurs shortly after installation, leading to inaccurate readings and compromised indoor air quality.

Aircuity stands apart through: patented system design, regular equipment calibration, and a comprehensive system warranty.

System Design

Aircuity’s centralized DCV uses one set of industrial grade sensors housed in a centralized sensing suite. One sensor is used to measure the supply, return, and outside air therefore, any offset errors of the sensor will be the same for both room and supply measurements to negate offset drift errors.

Sensor NIST Calibration

Although Aircuity’s industrial-grade sensors include offset drift cancellation, sensors can still drift over time in other ways, such as gain or linearity. To address this, Aircuity swaps out all sensors every six months (annually for some applications), using freshly NIST-calibrated replacements from our calibration laboratory. The Aircuity Calibration Lab is led by in-house sensor experts who have spent nearly 2 decades perfecting the process and we are the only company in the world who regularly and systematically gets all of our sensors back from the field. (This is now close to 10,000 annually.) The Cal Lab is critical to Aircuity providing accurate sensing and ensuring systems maintain performance for the life of the building. Each sensor that comes into the lab goes through a full cleaning, NIST traceable calibration, and a checkup of the sensor’s “health”. Sensor elements require review as they can need replacement anywhere from every 6 months to every few years depending upon application, location, system cleanliness and other factors.

Case Study

A Maryland school district case study highlights the importance of NIST-calibrated sensors. The district compared two schools with CO2 DCV—one using discrete sensors claiming low calibration needs, and the other using Aircuity. During renovation planning, they questioned which approach offered more accurate control for the life of the building. Technicians assessed the discrete sensors, comparing their readings to those on record. Results showed that fewer than 10 of the 65 discrete sensors operated within a 10% margin of error, while nearly two-thirds showed errors exceeding 25%—with an average error of 62%. Following these results, the district chose Aircuity for the high school renovation.

This case study illustrates that NIST factory calibration is crucial for accuracy, supporting active air quality control and reliable reporting. Errors like those found at the school are consistent across various studies, underscoring how sensor degradation compromises health, wellness, and learning in buildings designed to support these very needs.

Many ask about the calibration and maintenance needs of discrete sensors; the truth is, the cost is often prohibitive, leading to neglect. Over five to seven years, Aircuity proves more cost-effective in lifecycle terms, removing concerns over system accuracy.

Other Non-discrete Sensing Solutions

In analyzing other non-discrete solutions that attempt to mimic Aircuity’s established multiplexed system design, key considerations should include: “Are sensors pre-conditioned? How are they calibrated? Does the system use differential measurement? What is the verified performance per specification?” Unfortunately the industry lacks oversight or “sensor policing,” contributing to a low standard.

Conclusion

At Aircuity, we prioritize the health and safety of building occupants—from students and researchers to teachers, operators, and staff—who deserve environments that support their well-being. In labs, where higher air change rates are important where and when needed, our systems respond dynamically, with one client experiencing approximately 17,000 ventilation adjustments in a single year across 227 lab rooms in two buildings. We are committed to upholding the highest industry standards in calibration, system design, and integration. For nearly 25 years, our commitment has earned us the trust of clients who share our dedication to safe, high-performing buildings.

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