# Performance of Solar Control Films on Building Glazing: A Literature Review
## 6 Main Conclusions, Research Gaps and Recommendations  
Research studies on the performance of solar control films (SCFs) installed in building glazing systems were collected and thoroughly analyzed for this literature review article. As stated in the comprehensive literature review, the impact of SCFs on the performance of the transparent elements of building facades is a somewhat recent research topic with multiple subjects of interest. As a result, it has a large potential for investigation. The consulted research studies show that the application of SCFs to building glazing has numerous advantages as a rehabilitation solution. In fact, this recent glazing technology, which is continuously under development and investigation to create new and improvedproducts, aims to increase the energy efficiency of the glazing and promote indoor thermal and visual comfort for the occupants. The potential impacts resulting from the application of SCFs are shown in Figure 10.  
The assessment of the performance of SCFs is disperse in terms of methodology, analyzed variables and performance indices used. Moreover, most of the case studies of the existing literature are located in Europe and in East and Southeast Asia, corresponding to temperate, arid and tropical climate zones. It is also important to note that the performance of a given SCF depends on multiple conditioning factors such as the substrate to which it has been applied, solar orientation, type of air conditioning system and its energy efficiency, comfort conditions, existing shading and type of climate. Thus, the analysis of the performance of SCFs in existing glazing should consider these factors that directly affect the performance of the film. Even though some studies present a more complete analysis considering the evaluation of these conditioning factors on the film performance, the large majority is rather limited. Comfort assessment with SCFs installed in building glazing systems is also scarce in the existing literature, missing indoor glare analysis and thermal comfort analysis using adaptive models. Having identified the existing research gaps on the topic, future research considering the following potential studies should be conducted, singly and in combination, to further explore the potential of SCFs on building glazing:  
* Performance of SCFs considering whole building scenarios;
* Daylight assessment in the presence of SCFs installed in open plan spaces;
* Visual comfort assessment in the presence of SCFs, including glare analysis;  
Figure 10: Potential positive and negative impacts of the application of solar control films to building glazing. * Thermal comfort assessment in the presence of SCFs considering adaptive thermal comfort models;
* Sensitivity analysis of the conditioning factors such as film type and properties, film installation position, glazing type and properties, type of building, climate and solar orientation;
* A holistic analysis assessing the global performance of SCFs consisting of the thermal, luminous, energy, environment and economic performance assessment considering the conditioning factors with the highest potential impact;
* Single and multi-objective analysis of the performance of SCFs considering different conditioning factors. This literature review should positively aid in enhancing the limitations of existing studies and provide guidance for future research on the topic. Conceptualization, M.d.G.G. and A.M.R. ; methodology, M.d.G.G., A.M.R., J.P. and H.T; investigation, M.d.G.G., A.M.R., J.P. and H.T. ; writing--original draft preparation, J.P. and H.T. ; writing--review and editing M.d.G.G. and A.M.R. ; supervision, M.d.G.G. and A.M.R. All authors have read and agreed to the published version of the manuscript. The first and second authors gratefully acknowledge the support of FCT (Fundacao para a Ciencia e a Tecnologia) for the PhD Grants FCT PD/BD/127848/2016 and PD/BD/150576/2020, respectively.