Evaluation of indoor air quality using the decibel concept. Part I--proposal of new units

Weber-Fechner's law concerning the perception of sound by man with time expressed as a logarithmic function can also be used for the odour constituent used in the evaluation of indoor air quality in buildings. A new unit dB (odour) based on the concentration of Total Volatile Organic Compounds (TVOC) is proposed as it is currently the basis for determining the air change rate. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human small sensors is equal to one and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and a threshold concentration (TVOC) of 50 micrograms/m3-0 dB (odour). The upper limit is determined by the initial value of toxicity TVOC-25,000 micrograms/m3-135 dB (odour). Optimal values corresponding to PD = 20% (according to EUR 14449 EN) and admissible values corresponding to PD = 30% (see Table 3) are proposed, therefore the same values used to evaluate noise can be used to evaluate air quality and additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The determination of the required volume of fresh air for ventilation and air-conditioning systems according to the new principles is the subject of the Part II of this paper.