RT info:eu-repo/semantics/article T1 Two new models of direct luminous efficacy under clear sky conditions for daylighting in Burgos, Spain A1 Dieste Velasco, Mª Isabel A1 García Ruiz, Ignacio A1 González Peña, David A1 Alonso Tristán, Cristina K1 Luminous efficacy models K1 Direct illuminance K1 Modeling K1 Iluminación natural K1 Daylighting AB The use of daylight in buildings contributes to energy savings while significantly improving visual comfort and well-being. It is therefore very important to be able to quantify illuminance to take advantage of daylight. Although several models have been proposed in recent years to determine global and diffuse illuminance, the same may not be said of direct solar illuminance, which situates this study in an area of noteworthy scientific and technological interest. Two luminous efficacy models for clear sky conditions are proposed and the results of benchmarking with previous models from the literature are presented. Data collected in Burgos (Spain) were analyzed. Specifically, eight previous models for the prediction of direct illuminance were compared with our two new models. The two new models predicted illuminance more accurately than most of the classic models. Specifically, running the models on the training data yielded Root Mean Square Error (RMSE) values of 2.58 % and 2.76 % for the first and the second model, respectively. Likewise, the test data yielded RMSE values of 3.31 % and 3.49 %, and the Mean Bias Error values with the training data were 0.06 % and 0.11 %, respectively. The models achieved high accuracy levels with both the training and the test data sets. PB Elsevier SN 0960-1481 YR 2024 FD 2024-09 LK https://hdl.handle.net/10259/10839 UL https://hdl.handle.net/10259/10839 LA eng NO This research was co-funded by MCIN/AEI/10.13039/501100011033, “ERDF A way of making Europe” (Project PID2022-139477OB-I00), “European Union Next Generation EU/PRTR” (Project TED2021-131563B–I00) and Junta de Castilla y León, Consejería de Industria, Comercio y Empleo (Project INVESTUN/22/BU/0001). DS Repositorio Institucional de la Universidad de Burgos RD 08-may-2026