Temperature calibration for of the shelf sensor nodes
Calibration here is not related to the electrical performance of the device. As an example, the DS18B20 has a typical accuracy +/- 0.5C, from a 3-5V supply.

For a room thermometer, calibration refers to reflecting the room temperature to the value reported by the sensor, and is as much as a consumer feature than a technical necessity. There will be a small amount of self-heating in the node, there may be local heat sources in the room (say a TV, or a PSU), there may be air currents which lead to cooling, and a node placed higher up will most likely read higher than one placed low down. Many of these factors are not stable which makes the claimed accuracy rather unimportant.

Think of the calibration as applying an offset so the perceived optimum room temperature results in a similar reading from all sensors.

For example, there is a A/C thermostat next to me which reports temperature to a precision of 0.1C. Its exposed to sunlight through the window, and is next to a door. I guess it has maybe 0.5W of self-heating, except when the backlight is on. At different times, with the same room fabric temperature, the thermostat will record different temperatures - and that is not a reflection on the accuracy of the sensing device. Making the measurement accurate does not add value, since a person in the room also feels temperature differently as the conditions vary.