Design, fabrication, and calibration of the Building EnVironment and Occupancy (BEVO) Beacon : a rapidly-deployable and affordable indoor environmental quality monitor

Fritz, Hagen and Bastami, Sepehr and Lin, Calvin and Nweye, Kingsley and To, Tung and Chen, Lauren and Le, Dung and Ibarra, Angelina and Zhang, Wendy and Park, June Young and Waites, William and Tang, Mengjia and Misztal, Pawel and Novoselac, Atila and Thomaz, Edison and Kinney, Kerry and Nagy, Zoltan (2022) Design, fabrication, and calibration of the Building EnVironment and Occupancy (BEVO) Beacon : a rapidly-deployable and affordable indoor environmental quality monitor. Building and Environment, 222. 109432. ISSN 0360-1323 (https://doi.org/10.1016/j.buildenv.2022.109432)

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Abstract

Indoor Air Quality (IAQ) monitoring is essential to assess occupant exposure to the wide range of pollutants present in indoor environments. Accurate research-grade monitors are often used to monitor IAQ but the expense and logistics associated with these devices often limits the temporal and spatial scale of monitoring efforts. More affordable consumer-grade sensors – frequently referred to as low-cost sensors – can provide insight into IAQ conditions across greater scales but their accuracy and calibration requirements need further evaluation. In this paper, we present the Building EnVironment and Occupancy (BEVO) Beacon. The BEVO Beacon is entirely open-source, including the software, hardware, and design schematics which are all provided on GitHub. We created 20 of these standalone, stationary devices which measure up to 24 parameters at a one-minute resolution of which we focus on carbon dioxide, carbon monoxide, total volatile organic compounds, temperature, and size-resolved particulate matter. We investigated the efficacy of two different calibration approaches – device-specific and environment-averaged – for these sensors as well as also provide an extensive discussion considerations for each of the sensors. Calibrated sensors performed well when compared to reference monitors or calibrated gas standards. The CO sensors yielded the best agreement (r 2=0.98-0.99), followed by temperature (r 2=0.89-0.99), CO 2 (r 2=0.62-0.99), and PM 2.5 (r 2=-0.13-0.91). In all cases, the device-specific calibration approach yielded the most accurate results. We evaluated our devices through a successful 11-week field study where we monitored the IAQ in participants’ bedrooms. The work we present on consumer-grade sensors adds to the existing literature by considering sensor-specific calibration techniques and analysis. The BEVO Beacon adds to the successful line of similarly developed devices by providing an open-source framework that researchers can readily adapt and modify to their own applications.

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