Prototyping a construction-stage platform for as-built sustainability data management

New regulations and voluntary green certification schemes mandate the disclosure of as-built life-cycle global warming potential (GWP). Current construction-phase data management is a bottleneck because contractors and subcontractors manage data using fragmented digital workflows. This study utilizes an Action Design Research (ADR) approach to develop and pilot a low-code/no-code (LCNC) digital platform designed to integrate BREEAM reporting and automated A1 to A5 carbon calculations into routine site operations. This preliminary study was implemented over a two-month pilot on a commercial project in Tallinn, Estonia, involving five subcontractors. The System Usability Scale (SUS) method yielded an average score of 89.5, indicating good usability and successful workflow integration. Pilot demonstration and expert feedback confirmed that domain-specific, structured data capture significantly improves reporting quality, auditability, and calculation readiness. The findings demonstrate that digitizing the reporting responsibility enables lean-aligned carbon performance feedback, providing a solution for meeting emerging "as-built" environmental disclosure requirements.