Integrated environmental, energy and cost life-cycle analysis of windows: Optimal selection of components

Abstract

There is an increasing need for energy-efficient windows; however, these windows can have high embodied impacts and can be costly. This has not been thoroughly analyzed and the literature has mainly focused on the operational performance of windows. It is important to wisely select optimal windows that minimize energy consumption, costs, and environmental impacts throughout their life cycle, considering the influence of window orientation and climate data. This article presents an integrated cost and environmental life-cycle assessment (LCA) of window solutions, combining alternative glazing and framing options. Optimal window solutions were selected using a Pareto bi-objective optimization (costs vs. environmental impacts) for three different European climate regions, considering various window orientations. The influence of each window component (glazing and framing), as well as window properties (thermal transmittance and solar factor) on the overall environ-mental and cost life-cycle impacts was studied. Pareto optimal window solutions for warm climates highlight low solar factor windows, while for cold climates they highlight low thermal transmittance value. The glazing is the component with the greatest influence on the total environmental impacts (mainly operational). The impacts depend to a very great extent on the thermal transmittance values and solar factors. The life-cycle cost analysis shows that the initial investment in the windows has a high impact on the overall cost, even when a lifespan of 30 years is considered. This article provides insights into and recommendations for the design of windows by addressing different climatic conditions and window orientations.