Sustainable alternative to Bhutan's housing construction

Abstract

The global construction industry lacks innovation and contributes substantially to world energy consumption and greenhouse gas (GHGs) emissions. The construction model in Thimphu, Bhutan, shares a similar narrative, plagued by inadequacies of conventional on-site practices using energy-intensive materials, often resonating implications to other sectors like housing construction and delivery. This study posits emerging mass timber construction (MTC) as an innovative alternative to Bhutan's archetype mid-rise residential structure, focusing on voluminous assemblages of wall and structural systems. Using an analytical approach, this study compared the existing concrete building's essential economic and environmental sustainability with its hypothetical MTC equivalent. The economics focused on the life-cycle cost analysis (LCCA), while the environment focused on the embodied energy and CO2 emissions, estimated using the process-based method in a cradle-to-gate boundary limit. The environmental assessment unsurprisingly showed superior performances for the mass timber buildings relative to the conventional concrete ones.In contrast, the LCCA showed that mass timber buildings had material and built-up costs greater than concrete buildings by 30 and 38%, respectively, which is driven primarily by the high cost of timber in Bhutan. However, the scenario analyses regarding the end-of-life benefits and timber price reduction possibilities presented irrefutable evidence that the construction costs of MTC are cheaper or competitive with the concrete option. Integrating economics and environmental assessment establishes mass timber building as a viable innovative alternative, providing essential information to building developers and policymakers.

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