Energy simulation and modeling for window system: A comparative study of life cycle assessment and life cycle costing

The impact of the window system on building thermal performance is considerably complicated. It depends upon several interactive design factors and climatic diversity. Unfortunately, there is a lack of comprehensive life cycle assessment (LCA) involving operational thermal efficiency with embodied production. Yet upgrading the thermal efficiency of windows and cost of energy savings should be justified from the additional investment cost. Therefore, the study presents a holistic approach for optimizing the windows system integrating operational efficiency with comprehensive LCA and life cycle costing (LCC). The study employed energy simulation software FirstRate5 over a range of energy-efficient windows to assess potential design variables for energy expenditure. Performed simulations illustrate the dominance of façade insulation (R) above glazing in reducing energy consumption, roughly 87% of the cumulative reduction. However, the provision of a zero window is not an optimum solution for permitting daylight and fresh air. Thus, an analytical framework has been proposed for glazing to ensure thermal efficiency, lower embodied impacts, and cost-effectiveness. The resulting Pearson coefficient (r) shows a relatively higher thermal conductivity (Uw = 0.39) correlation with energy consumptions in a colder climate than hot- and warm-temperate environments. Thousands of simulations have been performed to generate data for developing linear regression models. In addition, Monte Carlo simulations have been conducted to validate the uncertainties of developed models. LCC analysis specifies the provision of glazing 40–68% of the window to wall ratio (WWR) feasible for optimal trade-offs. BIM-enabled LCA (Tally) identifies embodied environmental impacts for Aluminium, Timber, Fiberglass, uPVC, and Composite frame windows following the ISO 14040–14044 standards. Comparative analysis of different framed windows shows the suitability of using uPVC windows over others due to less cost, thermal efficiency, fewer environmental impacts, recycling possessions, and less energy demand at the manufacturing stage.