The study, published in Frontiers in Built Environment by Bonga PraiseGod Khuzwayo and colleagues at the University of South Africa, Durban University of Technology and partner institutions, tackles a familiar blind spot in construction engineering. Structural performance, construction productivity and environmental impact are usually assessed separately, often by different specialists using incompatible units and assumptions. That fragmentation makes it hard to trace why one material was chosen over another. The team’s answer is a multicriteria decision analysis procedure in which every criterion has an explicit engineering definition, a clear direction of preference and an auditable data source, all documented to three decimal places.

The framework rests on three calculated indicators. Structural Efficiency is defined as a common required axial design load of 30 kilonewtons divided by the self-weight of a one-square-metre wall panel, a deliberately narrow measure of demand relative to weight rather than a statement about structural safety. Production Efficiency comes from laboratory trials in which a three-person crew built 1.5-square-metre test panels, measuring completed wall area per hour. Embodied Energy sums renewable and nonrenewable primary energy over the product stage of the life cycle, covering raw material supply, transport to the factory and manufacturing, expressed in megajoules per square metre of wall.

Four alternatives entered the contest: conventional fired clay brick masonry, conventional hollow concrete block masonry, a ten-hole fired clay brick from Brickworks Limited, and a KEBE K190 vertically perforated clay brick. The two manufacturer-specific products came with independently verified Environmental Product Declarations, while the conventional systems relied on literature-based reference values. The authors were unusually candid about data provenance, classifying every input as experimentally derived, literature based, manufacturer reported, calculated or transferred. Because no direct productivity trials existed for the two branded bricks, they were assigned the conventional brick’s measured output and flagged explicitly as transferred analytical assumptions rather than measurements.

The pivotal step is the weighting. Rather than letting the researchers decide that energy matters more than speed, the framework uses entropy weighting, a technique borrowed from information theory that derives weights from the statistical dispersion of the data itself. Because Embodied Energy varied most sharply across the four alternatives, it captured the lion’s share of the discriminatory information, earning a weight of 0.706. Structural Efficiency received 0.216 and Production Efficiency just 0.078, the latter dragged down by three alternatives sharing the same transferred productivity value. The authors stress that these weights describe this particular dataset, not any universal hierarchy of engineering priorities.

The results were unambiguous. Conventional hollow concrete block masonry ranked first with an overall score of 0.984, combining the fastest measured construction rate of 1.027 square metres per hour with the lowest embodied energy of 295.650 megajoules per square metre. The KEBE K190 vertically perforated brick followed at 0.844, helped by the highest structural efficiency in the set thanks to its low self-weight. The Brickworks ten-hole brick scored 0.731, while conventional fired clay brick masonry trailed at 0.485, burdened by the heaviest wall and the highest embodied energy of 726.660 megajoules per square metre.

What makes the finding more than a one-off calculation is the battery of robustness checks. The researchers perturbed each of the least certain inputs, the transferred productivity values and the manufacturer-specific energy figures, independently by ten percent, and repeated the entire entropy calculation in all eight scenarios. No adjacent alternatives swapped positions. They then ran the same decision matrix through two entirely different aggregation methods, TOPSIS and VIKOR, and both reproduced the identical ranking. The ordering, in other words, is not an artefact of one mathematical recipe, though the authors caution that agreement among methods sharing the same inputs validates the aggregation, not the underlying data.

The study is equally notable for what it refuses to claim. The authors insist the framework is a screening tool for preliminary engineering decisions, not a substitute for code-based structural verification, fire and thermal assessment, or regulatory compliance. The structural indicator says nothing about compressive strength, slenderness or wall stability. The environmental assessment covers only the product stage and excludes transport to site, construction, maintenance and demolition. Embodied carbon, a distinct indicator from embodied energy, was left out entirely. The alternatives also differ in geographic origin and manufacturing technology, so the ranking is presented as a controlled methodological comparison rather than a market-wide verdict on any product.

For practitioners, the proposed workflow is a two-stage gate. Mandatory requirements such as compressive resistance, fire performance and durability must be verified first, as non-negotiable constraints that no environmental score can compensate for. Only then do feasible alternatives enter the entropy-weighted ranking, and any decision should be accompanied by the data vintage, system boundary and uncertainty statement so it can be audited and updated. The framework is also modular: cost, thermal resistance or embodied carbon can be added later, but adding any criterion or alternative forces a complete recalculation, because entropy weights are conditional on the full decision matrix.

The broader significance lies in the transparency the method demands. As buildings come under increasing pressure to cut their life-cycle energy demand, material choices that once rested on habit or single-metric comparisons are being subjected to the same auditable, data-driven scrutiny as any other engineering calculation. This study shows that when structural weight, build speed and embodied energy are placed in one matrix and weighted objectively, the traditional pecking order of masonry materials can change dramatically, and, more importantly, everyone can see exactly why.

Subject of Research: An entropy-weighted multicriteria decision framework integrating structural efficiency, construction productivity and embodied energy for masonry unit selection

Article Title: An entropy weighted multicriteria decision framework for masonry unit selection

Article References: Khuzwayo, B. P., Elsaigh, W., Rankine, R., & Walker, M. (2026). An entropy weighted multicriteria decision framework for masonry unit selection. Frontiers in Built Environment, 12, Article 1942111. https://doi.org/10.3389/fbuil.2026.1942111

Image Credits: AI Generated

DOI: 10.3389/fbuil.2026.1942111

Keywords: masonry, embodied energy, entropy weighting, multicriteria decision analysis, concrete blocks, clay bricks, environmental product declarations, construction productivity, structural efficiency, TOPSIS, VIKOR, sustainable construction