Figure 3
The architecture diagram titled “Actors slash Stakeholders” shows a blockchain-based cement emission monitoring process. At the top center, a dotted, rounded rectangle includes four stakeholders: “Regulatory Authority” with the government building logo, “Cement Manufacturer” with the cement bag logo, “Construction (end user)” with the construction icon, and “Independent Investigator” with the clipboard logo. A downward-left arrow labeled “Registration, reporting, certification” connects the Regulatory Authority to the Cement Manufacturer, while a downward-right arrow labeled “Audit requests” connects to the Independent Investigator. A horizontal left-pointing arrow labeled “Off-chain audits” links the Independent Investigator to the Cement Manufacturer. A downward arrow from a dotted, rounded rectangle box labeled “Stakeholders and actors interact with blockchain through D Apps” points to the “Fronted Decentralized Applications (D Apps) Application Programming Interface (A P I)” box with a monitor and mobile logo. From the D Apps slash A P I box, a rightward arrow labeled “View certification” connects to a vertical side connector labeled “Access logs and events on the B C,” which extends upward to the top dotted rounded rectangle box. A downward arrow labeled “Deploy, interact with, and publish events” leads from D Apps slash A P I points into a dashed, rounded rectangle labeled “Smart Contracts,” containing “Sustainability Certification S C” on the left and “Audit S C” on the right with document and Ethereum logos connected by a double-headed arrow. Below this section, a downwards arrow labeled “S C interactions and announced events are logged on the Ethereum B C.” A downward arrow connects “Smart Contracts” to the “Ethereum Blockchain” with the Ethereum logo, a rectangular box above the “Ethereum Blockchain” that reads “Regulators and auditors access information on I P F S through the I P F S hashes stored on the B C.” On the left, below “Cement Manufacturer,” a long leftward arrow points to “Smart Meters and C E M S (Continuous Emissions Monitoring Systems)” with a sensor logo, and a rightward arrow labeled “Upload emissions reports” connects it to “I P F S Slash Decentralised storage” with a server and cylinder logo. A note above explains that “plant structure, processes, and emissions data (through C E M S and smart meters), and other reporting requirements are stored on I P F S. This is communicated to S C s through the I P F S hash by the manufacturer.” From the I P F S storage, a downward arrow labeled “I P F S hashes” connects to Smart Contracts. Between I P F S and D apps Slash A P I, Bidirectional arrows labeled “Upload documents” above and “View documents” below. Below the smart meters, a downward arrow points to “Monitoring and Timing Oracles” with a triangle icon. A note above explains that “Oracles calculate periodic averages, emissions intensities, and other values upon which manufacturers are scored and report them to the S Cs.” A rightward arrow from Oracle, labeled “Report emissions violations” above and “Report periodic emissions data” below, leads to Smart Contracts.High-level system architecture of the proposed blockchain-based certification solution. Source: Authors' own creation/work