Pre-print: https://ssrn.com/abstract=5247212
The growing global population is increasing the demand for housing at the same time as the ecological limits requires much more resource-efficiency. Small multi-unit buildings are regularly proposed to increase material efficiency in housing construction. However, there are many ways to design and build buildings; which are the most materially efficient and what are the factors that increase material use? This paper quantifies material use and intensity (MI) in small multi-unit buildings using real world examples from 5 countries (Brazil, Canada, Greece, Switzerland and Nigeria) on 4 continents. We study buildings with 3 to 35 units built between 2014 and 2024. Overall, this study examines drivers of MI and how they vary (or not) within the 50 case study buildings.
When we compare the material use and intensity (MI) by floor area (per square meter), there’s a 20% difference. But when we compare by units, the difference is much bigger, about 150%. This is because some units are larger, have more bedrooms, or use space differently than others. Concrete use is dominant across countries with structural concrete making up 55% of the total material mass and concrete unit masonry 20%, representing 75% of the material mass across sampled buildings. Floors, decks, slabs, and exterior walls contribute heavily to this proportion but with large variations between countries. The work provides needed geographical diversity to our understanding of MI and understanding of how norms on space use influence MI.
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