Unfit for stranding assessment: a panel-scale multimodal-LLM audit of building-decarbonisation disclosure (BeDA)

Buildings account for roughly 34% of global final energy use and 37% of energy- and process-related CO$_2$ emissions. Stranding regulation now being enacted (New York City Local Law 97, the EU Energy Performance of Buildings Directive recast) presupposes that a building portfolio's carbon intensity can be measured per square metre and compared against a science-based pathway. Whether corporate disclosure is actually fit for that comparison has not, to our knowledge, been measured at scale. We introduce BeDA (the Built-environment Decarbonisation-disclosure Auditor), a multimodal large-language-model instrument, and apply it to a global firm panel (2,246 firms, 2003-2023). Its standards-compliance score is reliable across models and model families and convergent with three independent external criteria. Most disclosure is unfit: only about one built-environment firm-report in five discloses operational carbon intensity per $m^2$ (21.5% in a region-stratified sample of 200 firm-reports, Wilson 95% CI [16.4%, 27.7%], inter-extractor $\kappa$=0.95; 45.5% across 519 real-estate firm-reports, $\kappa$=0.97). The rate is roughly twice as high in Europe as in the United States (64-74% versus 37% for listed real estate). Among the 215 real-estate firm-reports for which an intensity can be constructed, 39% already exceed the Carbon Risk Real Estate Monitor (CRREM) 1.5 {\deg}C pathway's intensity limit. Credibility does not predict stranding readiness once portfolio size is controlled; this is a screening tool, not a forecast. The main obstacle to enforceable building-stranding regulation is therefore a measurable, jurisdiction-specific reporting gap, one that a targeted disclosure mandate can close and that BeDA can monitor.