The topic of Indoor Environmental Quality (IEQ) monitoring, meant as the sum of the four environmental domains (thermal, visual, acoustic, and air quality), is becoming increasingly relevant, mainly in tertiary-use spaces. The reason is to be found both in a growing interest in personal well-being, comfort, and productivity and in the advent of inexpensive and easy-to-use devices, the low-cost sensors. However, it is not possible to trace the clinical picture of the indoor environment based on the numerical quantity expressed by the sensor. It is necessary to combine this objective data with the subjective data of the user's personal comfort (IEC).