[Mikko]

My experience about HTU21 are not so good for outside usage. I have several humidity sensors outside and normally they last less than one year. One example is below, there is SHT11 and HTU21 sensor inside stevenson shield, fan aspirated H24. First picture is from July 2015, both sensors have the same readings. The second picture is about one year later, HTU21 sensor is giving much higher values. During the winter time HTU21 was showing 100%. For inside use HTU21 is very good, but for outside only Sensirion sensors have been working more than one year. Now testing SHT31 and that looks promising.
Mikko.