In the ENVIII unit temp/humidity/baro sensor, the barometric sensor is the QMP6988, and this can also be used to calculate altitude. In the QMP6988.h file line 138, there is a line for this:

float calcAltitude(float pressure, float temp);

... meaning you can call that method (calcAltitude) from the class in your .ino file.

Does anyone know which are the correct units (degC or degF) required for the float temp entry please? And also what units are returned for the calcAltitude (feet, meters etc)?

Many thanks.