## 2 Methods
### The IAQ Model Proposal--Basic Assumptions  
In the IAQ model construction process (our proposal), the commonly accepted approach is to transform individual concentrations of pollutants into subcomponents before they are aggregated into a single index (occupant satisfaction in %). However, summation of sub-indices can lead to situations in which all are under individual health thresholds, but the final indicator shows when the threshold has been exceeded. Conversely, the averaging of partial sub-indices can lead to an overall indicator showing an acceptable IAQ, even though one or more partial indicators are larger than their individual thresholds. One solution is to use the maximum value of all sub-indices to create the final form of the \(\sum\)IAQ\({}_{\text{index}}\). Taking these issues into consideration, the authors created the \(\sum\)IAQ model with three complication levels adapted to the purposes of potential applications of the model, as presented in Figure 3;  
1. Certification of a building, e.g., via the BREEAM system using (three sub-indices), called \"quality\";
2. Design, including perceptible contaminants affecting comfort and using the IAQ index when calculating the IEQ (five sub-indices), called \"comfort\";
3. Complex design, with the \(\sum\)IAQ\({}_{\text{index}}\) representing both comfort and health (seven sub-indices) called \"comfort/health\". The simplest one, \"quality\", is an inner part of the \(\sum\)IAQ\({}_{\text{comfort}}\) model and can be used separately for simple applications with the main purpose of supporting a green building certification, e.g., via the  
Figure 3: \(\sum\)IAQ model has three possible levels (i.e., similar to a Russian doll structure) adapted to the potential applications of the model. Figure 2: To determine the indoor air quality and indoor environmental quality (IEQ) indexes for the case study. (TC—thermal comfort, L—light quality, ACc—acoustic comfort). BREEAM system using three components, i.e., CO\({}_{2}\), HCHO, and TVOC. This model is used later on the case study of a BREEAM building. Figure 1 shows the processes influencing the morphology of the \(\sum\)IAQ model and Figure 3 provides a list of the pollutants for which three IAQ submodels were built, containing human-perceived contaminants (IAQ\({}_{\text{quality}}\) and IAQ\({}_{\text{comfort}}\) models), but also the IAQ\({}_{\text{comfort/health}}\) model for both perceptible and imperceptible pollutants, i.e., those that are not perceptible by humans but affect health and require additional energy for intensive ventilation for health reasons. There are potential sub-indices, such as IAQ(VOC\({}_{\text{non-odorous}}\)) or IAQ(CO) [5; 7]. Dust pollutants may have their sub-index both in the comfort model (if reliable curves of human sensory perception of PM concentrations are known) or in the IAQ\({}_{\text{comfort/health}}\) model if their health impact is considered to be the dominant feature. Considering the types of pollutants harmful to health assigned to the sub-indices of IAQ, we only consider the most important air pollutants (i.e., target emissions) that were given in the WHO guide in 2010 [5; 7]. Submodels of processes that impact on air quality in indoor environments, which can be distinguished as components of the IAQ model, were based on sensory satisfaction functions (index of occupant dissatisfaction (PD) with the level of air pollution). Subcomponents of the three potential IAQ models were classified according to their future potential applications: in the assessment of environmental quality index IEQ (models IAQ\({}_{\text{quality}}\) and IAQ\({}_{\text{comfort}}\)) or in the design of ventilation taking into account all possible harmful-to-health pollutants (model IAQ\({}_{\text{comfort/health}}\)). In our opinion, such systematization creates order and has a practical dimension as presented later on in the case study. The following are the target pollutant groups:  
1.