A Low Power System for Synchronising Buffered Air Quality Data

Air quality is becoming an increasingly recognised public health issue, with a strong focus on particulate matters (PMs) which have been shown to be a cause of respiratory problems. In addition to this carbon dioxide (CO2) concen-tration has been found to impact cognitive ability at higher levels. Bristol Research and Innovation Laboratory (BRIL), have designed, developed and deployed an Internet-of- Things (IoT) system to perform low-power, distributed monitoring of indoor environmental conditions within the Cardiff University School of Engineering building using LoRaWAN as the communication protocol. This paper discusses the significant design choices behind the platform, focusing on the compromises that were made to both minimize the power consumption and adhere with regional LoRaWAN data-rate limits; through a custom scheme of encoding timestamped, buffered sensor data. In addition to this, results from the system are presented and discussed where it is shown that the method adopted, a real-time clock (RTC) for achieving synchronization across the embedded devices, is adequate for scenarios where higher frequency readings across a range of sensors are required.