Thermal Performance of Alternative Construction Systems in Tropical Climates: An Outdoor Experimental Test-Cell Study

This study evaluates the thermal performance of three construction systems under tropical climatic conditions through outdoor experimental test-cell monitoring. The systems analyzed comprised a lightweight multilayer envelope (M1), concrete blocks incorporating raw rice husk as a 2.5% replacement of the fine aggregate by mass (M2), and conventional concrete block masonry (M3). Indoor air temperature was recorded continuously at 3-min intervals during a representative warm period from November 8 to 14, 2025. The lightweight system exhibited the highest indoor temperature variability and peak values, reflecting its limited capacity to damp transient thermal loads. The rice-husk concrete block system did not consistently produce lower daily mean temperatures than the conventional block system; however, it showed the lowest daily thermal amplitude and a narrower temperature distribution, indicating improved thermal stability. The conventional concrete block system presented comparable mean temperatures and intermediate thermal variability. These findings show that daily mean temperature alone is insufficient to characterize passive envelope performance and that peak exposure and thermal damping are also relevant indicators. The study provides comparative outdoor test-cell evidence on the influence of wall composition on indoor thermal response and supports the further evaluation of agro-industrial residues as components of building-envelope systems for tropical climates.