Investigating the effect of air temperature, color-correlated temperature of light, and ambient light intensity on students' sense of thermal comfort in the library space.

The sense of thermal comfort in educational environments is a key factor affecting both learning quality and student productivity. Inappropriate temperature and lighting conditions can cause thermal discomfort, decrease concentration, lead to early fatigue, and impede learning progress. Therefore, creating a space with optimal thermal comfort not only supports students' well-being but also plays a crucial role in designing effective educational facilities. This study aims to explore how different levels of ambient temperature (20, 25, and 30 degrees Celsius), light intensity (200, 400, and 600 lux), and the associated color temperature of ambient light (2700, 4000, and 7800 Kelvin) influence students' perceptions of thermal comfort while studying in a laboratory climate chamber. Conducted over four months (December to March 2024) with 90 male students from Ilam city, the research employed a three-way ANOVA analysis using SPSS version 27. Results indicated that correlated light color temperatures of 2700 Kelvin (at 25 degrees Celsius and light intensities of 200, 400, and 600 lux), 4000 Kelvin (at 600 lux), and 7800 Kelvin (at 20 degrees Celsius) significantly affected students' feelings of thermal comfort (p<0.05). The ambient temperature of the study hall and the correlated color temperature of ambient light, both independently and in combination with light intensity, significantly influenced students' thermal comfort. Although ambient light intensity alone did not have a major effect, it contributed to interactions with ambient temperature. The findings also confirmed that both ambient temperature and correlated color temperature significantly impacted students' thermal comfort in the library, with effects varying depending on the ambient light intensity levels (200, 400, and 600 lux). Specifically, at 200 lux, the 4000 K group showed differences from the other groups. At 400 lux, a combined effect was observed, with the highest comfort reported at 2700 K. At 600 lux, only the group with the highest color temperature (7800 K) experienced greater thermal comfort than others. In conclusion, the influence of light color temperature on thermal comfort depends on ambient light intensity and temperature conditions, with different levels producing distinct effects under each scenario.Methodology: This study was conducted by combining field methods and numerical simulation. Climatic data (temperature, humidity, wind speed) were collected using data loggers over a 12-hour period (8 am to 7 pm). Then, using ENVI-met 5.6.1 software, two scenarios of the current state (without vegetation) and the desired state (with vegetation) were simulated and compared. Model validation was performed by linear regression analysis and comparison of actual and simulated data.

Findings: The present study shows that vegetation has a significant effect on moderating urban climate. The findings indicate that treeless areas are 3-6 degrees warmer, and green cover reduces wind by 60% and increases humidity by 15%. Simulations with ENVI-met (with an accuracy of R²>0.9) confirmed that the removal of 160 plane trees on Khayyam Street in Ilam increased ambient temperature and reduced thermal comfort.

Conclusion: The results showed that urban vegetation plays a key role in moderating heat islands through shading and evapotranspiration mechanisms. Urban planning should focus on preserving and developing green spaces with resistant native species. The use of simulation tools such as ENVI-met can help design sustainable urban environments.