I’ve been evaluating the HTU21D temperature and humidity sensor made by Measurement Specialties as a possible DHT22 replacement for the emonTH. This is quite a new sensor, released in 2013. The Si7021 is also a possiblity with an identical pin-out.
The metrics speak for themselves:
*Assuming 1 sample per min and sleeping in between samples, 1440 min per day = 86400s per day. See HTU21D testing repo a [sub-repository of the emonTH] (https://github.com/openenergymonitor/emonTH/blob/master/sensor_test/htu21d) for full calculations.
An upgraded emonTH with a HTU21D sensor instead of DHT22 should benefit from substantially increased battery life, increased accuracy and lower cost.
There is some confusion with regard to the variants of this sensor I believe from my research that the HTU21D replaces the SHT21 made by Sensirion .
I hope to get a prototype emonTH with HTU21D up and running soon. I would be interested to hear if anyone has experience working with this sensor.
Thanks to @kobuki for posting an awesome comparison of various low cost temperature and humidity sensors. The HTU21D and si7021 hold their own in the comparison: