Experimental and numerical investigation of heat transfer, daylighting, and thermal comfort of light-transmitting concrete (LTC) wall

Data from the International Energy Agency reveals that building-related energy consumption accounts for over 30% of global final energy consumption. Developing high-performance, low-energy building envelope materials therefore holds considerable significance for coping with energy shortage and advancing environmental preservation. This paper investigated a novel construction material: light-transmitting concrete (LTC). Consisting of PMMA rods embedded in concrete, this material is capable of transmitting natural sunlight while reducing energy consumption. A systematic study on the heat transfer mechanism, indoor daylighting, thermal comfort, and indoor temperature distribution of LTC wall was conducted via experimental measurements and numerical simulations (ANSYS Fluent). Results revealed that the LTC wall increases average daily illuminance by 6.3%–14.8%, and the artificial lighting use is delayed by approximately 35 min, achieving lighting energy savings of 14.46% in summer and 3.48% in winter. The LTC wall exhibits strong seasonal thermal adaptability, maintaining a cooler and more stable nighttime environment in summer while enhancing indoor thermal comfort in winter through passive solar heat gains. Microscopic analysis indicated that PMMA rods act as thermal barriers in summer and form beneficial thermal bridges in winter. Additionally, the composite structure reduces deformation and stress under variable temperature conditions. Overall, the LTC wall lowers the average indoor temperature by approximately 0.5 °C in summer and elevates it by the same margin in winter, thereby improving thermal comfort and curbing building energy consumption.