The BMaC project started when sensors were to be added around an office building in order to measure temperature and other parameters, such as relative humidity. After deciding to use ESP8266 MCUs along with DHT22 temperature and humidity sensors, a simple prototype was put together, using a basic firmware written using the Sming framework.
It was found that DHT22 sensors were generally rather bulky and not very precise. The breakout boards used also had an improper resistor mounted on them, leading to the wrong temperature being reported. This sensor type also had the disadvantage of using its own one-wire protocol, instead of a standard interface method.
The DHT22 sensors got swapped out with BME280 MEMS sensors, which measure temperature, humidity, and also air pressure. A CO2 sensor was added as well, in the form of the MH-Z19. This required the firmware to support these additional sensors too. The sensor readings would be sent as MQTT messages, with a backend service...