When Reconfigurable Housing Reduces Household Expenditure: A Constraint and Cost-Transmission Model

Repository abstract

Can a home that changes configuration make adequate housing cheaper for its residents? Flexibility, disassembly and adjustable tenure already have substantial precedents; none implies that technical change automatically becomes a household saving. We develop a constraint and cost-transmission test connecting household–slot eligibility, a capacity-constrained partial equilibrium and a normalized expenditure account. The model separates three questions: does an intervention increase usable allocation, does it lower the clearing price, and do added charges erase the benefit? Two conditional propositions give the clearing price and necessary and sufficient expenditure thresholds. Matching-deficit certificates identify congestion that additional configuration options cannot remove. In a synthetic 120-household example, 50% configuration-compatible adoption with unchanged site authority leaves 90 allocations and increases expenditure by 1.7%; activating qualified sites permits 120 allocations and reduces it by 18.4% before additional site costs. That saving disappears when those costs reach 18.4% of baseline expenditure. Across 100 paired synthetic worlds, configuration flexibility alone reduces expenditure in 45 worlds, showing that mismatch and hard-capacity constraints require different responses. Independent exhaustive matching checks and numerical equilibrium checks support internal correctness. The contribution is an applied diagnostic synthesis, not a new matching theorem, universal AFI law or measured robotic-housing effect. Its use is to reject poorly targeted investments and specify what an empirical affordability test must measure.