Author(s)

ASHRAF RAGHEB

Abstract

The selection of low-impact building materials has emerged as a foundational strategy for achieving environmental sustainability in the built environment and for advancing the broader objective of carbon-neutral construction. Building enclosure systems incorporate a wide range of construction materials that collectively determine a structure’s embodied energy burden while simultaneously regulating its operational energy performance by mediating heat exchange between interior and exterior environments. This study employs a quantitative life cycle assessment framework to systematically evaluate the environmental impacts of a commercial office building across its entire service life. A two-storey office building situated in ASHRAE Climate Zone 5A in midwestern USA is modelled over a 60-year lifespan, with environmental impacts assessed from cradle to grave. The study quantifies and compares the total impacts attributed to each major building assembly system: structure, walls, floors and roof, expressed per unit of gross floor area across eight impact categories spanning air, water and land. The analysis identifies the roofing system as the assembly with the highest environmental burden, driven primarily by the embodied energy and manufacturing emissions associated with polyisocyanurate rigid insulation and a black ethylene propylene diene monomer membrane. A sensitivity analysis is subsequently conducted to evaluate the substitution of these high-impact materials with more environmentally benign alternatives, specifically expanded polystyrene insulation and a white thermoplastic polyolefin membrane and to quantify the resulting reductions in total life cycle impacts across all categories.

Keywords

environmental impacts, roof systems, life cycle assessment, sensitivity analysis