Energy consumption in buildings depends on several physical factors, including its physical characteristics, various building services systems/appliances used, and the outdoor environment. However, the occupants’ behavior that determines and regulates the building energy conservation also plays a critical role in the buildings’ energy performance. Compared to physical factors, there are relatively fewer studies on occupants’ behavior. This paper reports a systematic review analysis on occupant behavior and different modeling approaches using the Scopus and Science Direct databases. The comprehensive review study focuses on the current understanding of occupant behavior, existing behavior modeling approaches and their limitations, and key influential parameters on building energy conservation. Finally, the study identifies six significant research gaps for future development: occupant-centered space layout deployment; occupant behavior must be understood in the context of developing or low-income economies; there are higher numbers of quantitative occupant behavior studies than qualitative; the extensive use of survey or secondary data and the lack of real data used in model validation; behavior studies are required for diverse categories building; building information modeling (BIM) integration with existing occupant behavior modeling/simulation. These checklists of the gaps are beneficial for researchers to accomplish the future research in the built environment.

The effects of partially replacing of cement with glass powder in concrete were studied and therefore found that some extent could be replaced which contributes in strength development. Cement was partially replaced with glass powder at varying percentages such as 10%, 20% and 30% and several concrete cylinders were casted along with plain concrete specimen. The cylinders were tested for compressive strength and split tensile strength at the age of 7, 14 and 28 days and were compared with the results of plain concrete. The overall test results indicated that the waste glass powder could be utilized in concrete as a good substitute of cement up to particle size less than 75μm. In replacement of cement with glass powder of 10%, the compressive strength and split tensile strength were reduced in 7th days for all samples. The 20% replacement of cement by glass powder met maximum compressive strength as compared to that of plain concrete. At 28 days, 30% replacement of cement by glass powder met maximum split tensile strength as compared to that of plain concrete.