## 2 Methods  
In this section, source, criteria, and methodologies are presented that were used to select literature papers and extract information from them. The scope of the research is to identify works featuring solutions for the control of indoor environment to improve or preserve thermal comfort. Therefore, the authors searched for papers presenting simultaneously:  
* A clearly identifiable thermal comfort model with inputs and outputs;
* A strategy that exploits the outputs of the thermal comfort evaluation to control well-indicated variables connected to the indoor environment. For example, a paper discussing an innovative control method of indoor temperature, only indicating the set-point value without specifying the origin of this value, would be excluded; a paper explaining that the set-point equates the neutral temperature calculated from predicted mean vote (PMV) model would not be excluded. The search has been performed in the Scopus database, with the query string graphically visualized in Figure 1.  
Figure 1: Graphical visualization of query string. Keywords in filled boxes were searched with “OR” logic. Scopus nomenclature: TITLE-ABS-KEY = title, abstract or keyword; PUBYEAR = publication year; DOCTYPE = document type (ar = article; cp = conference proceeding); * = wildcard character. Thermal comfort- and control-related keywords have been searched in the title and in other informative fields (abstract, keywords), to try and include both comfort-centered (comfort-related words in title) and control-centered (words related to control methods or systems in title) studies. The search has been restricted to the 2017-2021 period. The reason behind this limitation is that the search query includes practical control aspects that are linked to technological evolution. Moreover, a very large number of studies have been published on the investigated topic even in such a small period, indicating rapid progress in the field. This choice, therefore, allowed to consider only the most recent advancements while examining a large number of papers. Since this survey aims to collect primary references, only articles and conference papers have been retained. The search returned 2472 results. All the following selection processes have been performed manually. Initially, abstracts have been skimmed through to exclude the papers that clearly did not fit the criteria. A total of 244 papers passed this stage, were exported from Scopus in.csv format, and were analyzed. After a final selection based on relevance to the scope and presence of the required information, 166 of them have been included in the present survey and recorded in a reference database. A total of 123 of them are recalled in this paper. Table 1 summarizes the selection steps, tools, and criteria described above. The.csv file created at the third stage of the selection process only contained the fields exported from Scopus search, including authors, affiliations, title, year of publication, document type, source title, identifiers, keywords, and open access availability. To make the database more informative and to allow the extraction of statistical figures, the file was cleaned of fields not relevant to this research (e.g., funding details or PubMed ID) and manually completed with new fields based on full paper content, such as  
* Monitored quantities (inputs) and control variables;
* Hardware and software;
* Thermal comfort model category and description;
* Control algorithm type and description;
* Application context (season, building type and possible HVAC system);
* Multi-occupancy;
* Validation;
* Strengths and limits;
* Estimated cost of equipment (where specified);
* Level of readiness. This led to the spreadsheet in the Supplementary Materials, which is the true heart of the work, and the base for all the analysis in Section 3. Here, results are presented in tables and figures; the former summarize information about studies belonging to a given sub-group, whereas the latter provide an overview of the investigated article set.