Open-Source LoRaWAN Sensors for Distributed IoT Networks: Crowdsourced Environmental Data Collection for Climate Resilient Cities

Accurate, high-resolution air temperature data over long time periods is essential for understanding microclimates, heatwaves, and urban heat island (UHI) effects. However, accessing such data remains a challenge in urban climate research. This paper presents the development of a distributed IoT network using bespoke LoRaWAN heat sensors for real-time air temperature and humidity monitoring. The research follows an action-based approach, integrating three iterations of sensor design and multiple deployments across London in collaboration with various partners. The first iteration, developed in 2022, demonstrated sensitivity to hyperlocal microclimatic variations and provided evidence of UHI effects, performing comparably to commercial data loggers while offering a lower-cost alternative. These insights informed the second iteration, which incorporated solar power for sustained operation with reduced maintenance requirements, and the third iteration, designed as an open-source citizen science board to support community-led environmental sensing. By providing open-access schematics, PCB design files, and 3D-printable enclosures, this work enables users to build their own sensors and contribute to crowdsourced climate data collection. Over three years, this research aims to design and develop cost-effective, self-managing, lightweight wireless heat sensors to establish a London-wide LoRaWAN microclimate network for input into climate mitigation planning. By making the tools open source and sharing the real-world deployment challenges and lessons learned, we also aim to help address difficulties in accessing global and local weather station datasets, supporting climate resilience efforts by enhancing data accessibility and engagement in environmental sensing at scale.