# Advancing Sustainable Textile Metrology: Reflectivity Measurement with Controlled Light Sources
## 3 Results and Discussion
### Reflectance Ratio
For additional statistical analysis of the results for the reflectivity of the knitted macrostructures, the coefficient of variation (CV) of the reflective ratio was also calculated as it indicates how stable the reflectivity of each textile sample is under different lighting conditions. The results are summarized in Figure 7.  
The analysis shows that sample C has the highest CV (6.36%), meaning its reflectivity varies the most depending on the lighting conditions. This makes it the least reliable of the six fabric designs for environments with different lighting. The lowest CV (3.09%) is found in sample F, which means its reflectivity varies the least depending on the lighting. However, sample F has the weakest reflectivity of all the samples (Figure 6), and this does not make it the best choice. Samples B, D, and E have moderate variation (between 3.8% and 4.3%), indicating that they are relatively stable but can be influenced by specific conditions. Sample A has a CV of 5.08%, placing it in the middle range--it is not as variable as C, but not as stable as F. Therefore, for applications that require moderate predictability of reflection, samples B and D could be a good compromise. The correlation between CV and the average reflectance ratio (RRav) is shown in Figure 8. The red line represents the regression relationship between the average reflectance and the coefficient of variation. The derived regression equation is as follows:  
\[CV=-10.9929+10.5661 RR_{av} \tag{4}\]  
The red area marks the confidence interval. It visualizes the degree of uncertainty in the results: a wider area means greater data dispersion. Most points follow an upward trend, meaning that samples with higher reflectivity are more prone to variate under different lighting conditions. The correlation coefficient (r = 0.49) indicates a moderately strong positive relationship between average reflectance and the coefficient of variation, i.e., not all samples with high reflectivity have high variation. Figure 6: The average reflectivity of each sample under the four lighting conditions. The letters A to F represent coded textile samples as defined in Table 1.  
Figure 7: Coefficient of variation (CV) of the reflective ratio of the textile samples. The letters A to F represent coded textile samples as defined in Table 1.  
Figure 9 shows the distribution of reflectance relative to the type of lighting. This view emphasizes the impact of lighting conditions independent of fabric construction. It is clear that the highest mean reflectance ratio occurs under daylight conditions and fluorescent lighting. This means that the investigated textile samples reflect the most light in natural conditions and would perform similarly in commercial and industrial environments. Regular store light gives lower reflectance ratio values than fluorescent lighting due to its warmer spectrum. Confirmation of this is the fact that home lighting, which has the warmest spectrum of the conditions studied, also leads to lower values of the samples' reflectivity. Finally, it is clear that regular store lighting and home lighting do not activate the chosen reflective thread used for the knitted samples as effectively.