## 2 Literature Review  
### Evolution, Main Applications, and Features of Post-Occupancy Evaluations  
Post-Occupancy Evaluations (POEs) aim at assessing building performances, users' behavior, and feedback regarding existing buildings during the operational phase and once the building has been occupied for some time [27; 28; 29; 30; 31]. POEs were first introduced in the UK and US in the 1960s in order to assess building performances from user perspective, by means of interviews, questionnaires, photographic surveys, and walk-through surveys [27; 28]. The major developments of POEs were during the 1980s, aiming at analyzing and optimizing the facility management and design [29]. POEs had been performed in the US, mainly in the public sector, UK, New Zealand, and Canada [32], and, since a correlation between workplace features and worker productivity was proposed in 1985, they have been also applied in the private sector to improve costumer and worker satisfaction and to optimize the workplaces [30]. In the mid-90s, the interest moved from analyses during the operational phase alone to an entire building life cycle process, i.e., Building Performance Evaluation (BPE) [33; 34]. Insights and findings from POEs could be applied in the subsequent design and building life cycle process [34; 35; 36].  
In the last two decades, POEs have mainly been applied to assess and optimize building energy performances, and to reduce the building environmental impacts [37]. A less investigated but promising research field is the optimization of occupancy patterns, and cleaning activities and contracts. Space features and workplace cleanness have been classified as basic factors affecting user satisfaction [5], and, consequently, user productivity. The variable \"interior use of space\" can account for around 43% of the variance in employees' enjoyment at work, well-being, and perceived productivity [6].  
As above mentioned, POEs are analyses of the built environment, aiming at defining the effectiveness and functionality of spaces for users, building performances, and user satisfaction and perception regarding facilities in general and workplaces in particular [27; 38]. There are three levels of POEs depending on accuracy, time needed to be performed, tools, and levels of invasiveness of user privacy [7; 30]:  
* Indicative POEs enable to perform overall non-invasive analyses of the building, with selected interviews and photographic surveys to detect critical areas of the building.
* Investigative POEs are more in-depth analyses, and more invasive, with questionnaires, video recordings, and measurement, and they are meant to find causes and consequences of the building performances.
* Diagnostic POEs are the most in-depth analyses, with high levels of user privacy invasiveness and high costs, since they can imply the use of sensor systems to monitor the building, providing data to analyze and optimize building performances and future designs.  
Despite being expensive and invasive for user privacy, especially when performing diagnostic analyses, POEs can have several benefits, ranging from the optimization of the operational phase in terms of performances and user satisfaction, to an increased facility adaptation to organizational change and growth over time [27; 30], and to the definition of design criteria and requirements based on actual user and space needs for similar buildings [39].