Affordable and portable non-motorised IoT smart weather observation device for outdoor urban microclimate and thermal comfort studies

A finer and higher spatial scale measurements of atmospheric variables, Air Temperature (AT), Relative Humidity (RH), Wind Speed (WS), and Mean Radiant Temperature (MRT), are essential for human-scale thermal comfort and Urban Heat Island (UHI) studies to help architects, urban designers and landscape architects to make thermally comfortable and climate-responsive design decisions. Fixed wireless sensor units with real-time data monitoring facilities are impractical and not cost-effective as they require more sensor units in a short spatial distance to capture the finer spatial scale measurements. On the other hand, the commercially available sensor units are expensive. Also, they do not facilitate the Globe Temperature (GT) measurements, a cost-effective way to calculate MRT, according to the ISO 7726 (1988) standards. Hence, we developed an affordable and portable weather station platform, with an edge device (containing Raspberry Pi micro-controller and sensors to measure the required atmospheric variables) and a centralised server. This GPS-enabled device is capable of measuring AT, GT, RH and WS, and can also perform some data manipulation, and pre-processing, store the data, and communicate the collected data to a centralised server via cellular for further processing and storage. To assess its performance, especially for human-scale thermal comfort and UHI studies, we carried out three tests under two scenarios ‘On the Move’ and ‘Stop-and-Go’: Test 1 to find the best housing and shielding design for the device, Test 2 to assess the GPS accuracy and performance, and Test 3 to understand data consistency, latency, sampling rate and stabilisation. We found that the ‘3-D printed semi-circular louvre’ performed well in protecting the AT sensor. Overall, the portable weather station worked well under the ‘Stop-and-Go’ scenario compared to ‘On the Move’ due to the finer and higher spatial inaccuracies of the GPS sensor.