# Performance of Solar Control Films on Building Glazing: A Literature Review
## 5 Discussion of Existing Studies on the Performance of Solar Control Films
### Climate  
SCFs initially emerged on the market with the main aim of reducing excessive solar heat gains through glazing systems. As a result, the majority of the research studies evaluate the performance of SCFs when installed in buildings located in hot climates with high solar radiation levels. As previously mentioned, the window film market has been evolving and new types of SCFs that aim to balance different performance aspects (such as visual and thermal comfort) and increase the glass performance during the cold season, other than reducing excessive solar gains, have been developed. Hence, the evaluation of the performance of SCFs should also be carried out for temperate and cold climates.  
Figure 9 shows the location and respective climate of the existing research studies on the performance of SCFs when installed in building glazing. The existing studies reported in the literature review considered case studies located on tropical (tropical monsoon [34]), arid (cold arid steppe [35]; hot desert [36; 37; 38; 40; 51]), temperate (humid subtropical with a hot summer [41; 52]; temperate oceanic [42; 43; 53; 54; 55]; hot-summer Mediterranean [19; 44; 45; 56; 50]; monsoon-influenced humid subtropical [47; 48; 49]) and cold (warm-summer humid [57]) zones, in accordance with the Koppen-Geiger climate classification [58].  
SCFs show a better performance when installed in hot climates, particularly during the hot season (higher temperature and solar radiation levels) when the reduction in excessive solar heat gains is more significant. The performance of SCFs is less noteworthy when installed in cold climates and/or during the cold season because they can promote an increase in the heating energy needs due to the reduction in solar heat gains through the glazing. Low-E films are more adequate for temperate or cold climates since they can better balance heat gain/losses through the glazing system to meet the different required indoor comfort conditions throughout the year.  
Figure 8: Type of glazing substrate (**a**) and type (**b**) and installation position (**c**) of solar control films assessed by the existing studies.  
in building glazing systems. In addition, Optics [29] and Window [30] software, developed by the Lawrence Berkeley National Laboratory, were common complementary simulation tools to compute the thermal and solar optical properties of the glazing systems with and without SCFs [19; 34; 35; 44; 46; 50; 56].  
The computer simulation models used by the reported studies were usually calibrated with experimental data, involving the comparison and subsequent approximation of the simulated values to the ones experimentally collected. The most common calibration variables are indoor air and/or glass surface temperature and energy consumption. The statistical parameters normalized mean bias error (NMBE) and coefficient of variation of the root mean square error (Cv(RMSE)) are usually computed to assess the quality of the calibration of the simulation models [44; 46; 49; 57]. After a successful calibration, the computer simulation model is considered to accurately reproduce the case study and thus suitable to perform trusting simulations of the performance of the glazing systems.