Hi everybody,
I was trying to built a wheatherstation using several bme sensors (bme280, bme680)
All of them give me values which definitly are far away from reality. For example my common homedevice is
measuring 24.3 °C and 52 % for actual ambient Temp and Humidity while my bme680 gives me 28.87 °C and 40.95 % . This effect does not get better on using a bme280
Somebody has an idea what´s wrong with these measurements ?
Actually I was testing with the Adafruit_bme680 library and corresponding examplecodes.
Could be your "standard" is wrong or your BME's are cheap clones with no chance of accurate measurement. Do you get the same temperature and humidity readings when you compare the BMEs' readings?
I don´t get the same values by changing the sensor, just another set of housenumbers
You probably should invest in a known quality sensor to use as a calibration source. Try Adafruit or equivalent.
might make ssense, I purchased all my sensors on AliExpress but I never thought that all of them can be this bad
Don't sell them short. I'm sure they can be even worse than you experienced.
There's an old nautical saying, "never take two chronometers to sea. Always take one or three."
Avoids the problem you're having 
Test each sensor along with the control sensor in a freezer, a refrigerator, a room and an oven (to achieve 40c ~ 45c). Record data from the two sensors over several hours. Map the data together and write the correction function. Label each BMP with its correction.
This looks too much laboratory stuff which I don´t have at home. I just wanted to built a cheap DIY-weatherstation with a nice design for my living room. The photo shows the physical result but as a simple housenumber generator it´s not the right design. At least I expected some feelable results close to real situation.
That's a pretty cool looking project. Spend the extra 15 bucks and get an accurate sensor.
This guy has tested a few (click).
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BME280 and BME680 is always higher temperature and lower humidity (I suspect self-heating) I think those sensors are not for uncalibrated DIY projects)