Framework for optimising daylighting and passive indoor thermal comfort in single-banked office buildings in the temperate dry climate of Nigeria

Many researchers have differed on the optimum values of Daylighting and Passive Indoor Thermal Comfort (DPITC) determinants in tropical climates. The study is aimed at developing a framework for optimising DPITC in singled-banked office buildings, during the activity period (8 a.m. to 5 p.m.), in the temperate dry climate of Nigeria. It was achieved by evaluating the effects of orientation, window-to-wall ratio (WWR), R-values of external wall insulation material, and shading devices on DPITC. A quantitative research design using an explorative design approach was employed in the study as well as an experimental research strategy through simulation method to optimise DPITC. The study used the Federal Secretariat building of Nigeria as a prototype of a single-banked office building. The Google SketchUp Pro 2022 and OpenStudio 3.3.0 simulation tools were used to evaluate the prototype building from January to December 2023. The data generated was analysed using relevant statistical tools (MANOVA, ANOVA, column charts, graphs, and tables). The findings revealed that the best WWR for daylighting and passive indoor thermal comfort are 20% and 15% respectively, while the compromise value was 20%. It was also noted that the R-value of the external wall insulation material does not affect the daylighting of an office building but affects the passive indoor thermal comfort, where the optimum R-value was of 3.26 m2·K/W. The mathematical model was developed as A= 224.58 − 1254.84 WWR+ 102.87 PF − 4.11R … … .1 where A is orientation, WWR window-to-wall ratio, PF projection factor, and R is the R-value of the external wall materials.