Break-Even Conditions for High-Rise Modular Public Housing: A Probabilistic Life Cycle Sustainability Assessment

초록

Despite growing interest in modular integrated construction (MiC) for public housing, procurement decisions remain dominated by initial cost comparisons that overlook broader social benefits. Quantitative evidence on the conditions under which these benefits can offset cost premiums is currently absent. This study identifies break-even conditions for high-rise modular public housing using a probabilistic life cycle sustainability assessment (P-LCSA). Four non-market social benefits-carbon reduction, safety improvement, waste reduction, and early occupancy-are monetized and evaluated through 10,000 Monte Carlo simulations for 17-story and 25-story public housing scenarios in Dongducheon, South Korea. Deterministic incremental social benefit-cost ratios (IS-BCRs) of 0.353 (17-story) and 0.226 (25-story) indicate that monetized benefits offset only 23-35% of cost premiums. Early occupancy dominates total benefits (87%), while Monte Carlo simulation confirms P(IS-BCR >= 1.0) = 0.00% in both scenarios. The contribution lies not in reporting a negative result, but in quantifying the viability gap and identifying decision-relevant thresholds. Break-even analysis shows reducing cost premiums to 8-10% as the most plausible pathway, while a hybrid package combining cost reduction, carbon pricing, and schedule compression achieves IS-BCR above 1.0. The study contributes a probabilistic decision-support framework that reframes the question from whether MiC is viable to what conditions are required for social justification.

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