ClimateBOX: A low-cost and open-source monitoring device for personal thermal comfort evaluation

Abstract

In a new era of indoor environmental monitoring, the combination of cost-effectiveness and reasonable accuracy makes low-cost sensors a valuable tool for thermal comfort research. Unfortunately, steep learning curves, the complexity of calibration methods and insufficient documentation on existing devices prevent most of the research community from benefiting from these exciting technological advancements. While previous work has focused on substantiating the effectiveness and accuracy of low-cost units, little has been done to actively share the knowledge and enable more widespread use of low-cost sensors.Through an iterative design process, we developed the climateBOX, an open-source thermal comfort monitoring unit for less than 50 US$. The simplistic design, a streamlined calibration method and comprehensive documentation, including step-by-step instructions hosted by an open-access platform, make the climateBOX especially suitable for inexperienced users seeking an entry point to the field of low-cost monitoring technology.Comprehensive testing of sensor-to-sensor error, accuracy and long-term use of 15 units in the field, revealed the devices' high accuracy and reliability. Furthermore, based on the results from our analysis, we developed a simplified, single-point calibration method that removes an often-considerable barrier to the pervasive implementation of such units in the field. This allows to build and use the unit without the need for expensive reference equipment.The climateBOX and the associated open-source platform will enable the pervasive collection of thermal comfort data in greater quantity and variety and will significantly facilitate widespread access to low-cost comfort monitoring technology throughout the whole research community.