## 3 Results
### Question 2: Why Is the IEQ Model Needed? It is well-known that people spend most of their time indoors, and IEQ significantly impacts the occupants' health, comfort, and working performance [18; 19; 20; 21; 22]. Previous studies identified that poor IEQ could cause sick building symptoms (such as dry eyes, stuffy nose, and headache) [23; 24] and may have a close connection with the prevalence of certain diseases (such as rhinitis and migraine) [18; 19]. These health effects would inevitably result in uncomfortable workers and poor performance. Besides the occupants' perspective, IEQ in the working environment has also aroused employers' interest since an unhealthy IEQ might lead to leave being taken due to ill health and low productivity, thereby lowering yields. It has been known that personal experience accounts for a large proportion of companies' operation and maintenance costs [25; 26]. Take an employee in California as an example; [PERSON] and [PERSON] [27] claimed that decreasing 1% in one employee's productivity  
Figure 2: High-frequency items occurring in the abstracts. Note: Colors indicate the cluster to which an item was assigned by the clustering technique that is used by the VOSviewer, while the circle’s size represents the related item’s research frequency [12]. was equal to USD 665 being lost yearly. Conversely, improving workers' performance could result in a USD 20-160 billion increase per year [25]. Additionally, the impact of IEQ on occupants also concerns the managers of schools since children are much more sensitive to IEQ than adults [28]. Poor IEQ not only negatively impacts children's comfort at school [29] and their performance [30] but also might cause health problems such as fatigue, stuffy nose, and headaches, which may impede children's development [31]. For example, [PERSON] and [PERSON] [32] identified a negative relationship between classroom, temperature (within a specific range), and students' test scores. An EU-level project, SINPHONIE (Schools' Indoor Pollution and Health: Observatory Network in Europe), which investigated the IEQ in 53 schools across 12 European countries, found a significant impact in terms of visual quality, particularly the amount of daylight, on students' school performance [33]. [PERSON] and [PERSON] [34] reported the detrimental effect of poor classroom acoustic quality on students' speech communication and learning ability. Moreover, poor IAQ, such as high concentrations of VOC (volatile organic compounds) and PM\({}_{2.5}\) (particles that are 2.5 microns or less in diameter) or inadequate ventilation rates in classrooms, were also detrimental to school children's health and performance [35; 36; 37]. All these IEQ aspects are essential to occupants' health, comfort, performance, and overall IEQ satisfaction. However, the degree of importance of these aspects is not so clear, and it differed among different occupants with different occupancy duration in various types of buildings [7; 38; 39]. Building managers (or others with the right to control the IEQ in the buildings) usually allocate attention and energy resources based on their own experiences and understanding of the different IEQ aspects. Therefore, identifying how different IEQ factors impact occupant satisfaction could help building managers to decide what IEQ aspect should be prioritized, especially when resources are constrained [40]. Given the above, all the building's designers, owners, and managers should be encouraged to invest in modifying the building designs or building operations if these modifications could improve the occupants' health, comfort, and performance. Therefore, to help decision-makers to better understand the quantitative relationship between the  
Figure 3: High-frequency items occurring in the various abstracts.