The residential renovation market exhibits severe information asymmetry. A homeowner commissioning work cannot reliably judge whether a contractor's quote reflects a fair price for the scale and quality of work actually delivered — a textbook lemon market (Akerlof 1970), and more precisely a credence good (Darby and Karni 1973; Dulleck and Kerschbamer 2006). This paper proposes the Verified Renovation Quote (VRQ) framework, integrating four components: (1) a 170-category reference-price layer with indicative ranges published openly and precise prices reserved for verification, built on the openly published Japan Construction Cost Database (JCCDB) item schema (65,729 items across 398 categories; item names, categories, and units only); (2) a contractor-tier margin model making scale-appropriate profit ranges explicit rather than hidden; (3) a three-stage verification judgment (approved / conditional / rejected) refusing to certify quotes lacking internal consistency; and (4) tamper-evident, time-anchored certification via SHA-256 hashing and Bitcoin/OpenTimestamps anchoring through an institutionally independent verification body. The framework is presented as a market-design intervention; empirical validation is deferred to future work.
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Toshikatsu Oga (2026) studied this question.