Impacts of the operational phase on the life cycle cost of permeable pavements.

Permeable pavements offer a promising strategy for reducing surface runoff and capturing rainwater for non-potable uses in buildings. However, the systematic incorporation of their broader benefits into life cycle based economic assessments remains limited. This study develops a Life Cycle Cost Assessment (LCCA) framework for permeable pavement models that integrates rainwater use in buildings and applies it to a Brazilian case study. Three permeable pavement models (asphalt concrete, cementitious concrete, and concrete paving block) are assessed alongside a conventional impermeable asphalt concrete pavement. The framework encompasses all life cycle phases, from raw material extraction to end-of-life, with particular emphasis on the operational phase, in which benefits are systematically quantified and monetised. Net present value (NPV) and discounted payback period were used as decision-support indicators. The results show that, despite the lowest initial cost, the conventional pavement yields a negative NPV (-R$ 142,189). On the other hand, all permeable models result in positive economic returns. Concrete paving blocks showed the highest initial cost, but still achieved a positive NPV (R$ 51,437) with a longer discounted payback period (10.8 years). Permeable cementitious concrete was the most cost-effective model, showing the highest NPV (R$ 72,780) and the shortest payback time (9.0 years). The findings demonstrate that operational-phase benefits, such as improved stormwater quality, flood mitigation, reduced heat island effects, carbon sequestration, changes in street lighting demand, fuel consumption, and rainwater harvesting, are decisive in offsetting higher initial costs. By explicitly accounting for operational benefits that are typically overlooked, the framework proposed herein broadens the scope of conventional economic analyses and strengthens the basis for informed decision-making in urban infrastructure planning.