Embodied Energy and Lifecycle Costs: Questioning (Mis)conceptions about Underground Construction

In the construction community, underground construction is perceived as being significantly more costly and more energy-consuming than comparable surface construction. Although the literature is scarce, studies that have attempted to quantify this difference tend to compare built projects in very heterogeneous conditions. The objective of this article is to present the results of life cycle cost and energy consumption simulations conducted as part of a large research project at our home institution. This article begins by examining the preconceptions the construction industry seems to have about underground construction as reported in the press from 2007 to 2017. Then, we present the method and results of two unpublished studies on the differences in costs and energy consumption of a hypothetical commercial building project in two different geological contexts. We find that energy consumption is 15% higher but also 4% lower. We also find that underground construction in unconsolidated sediment ground is approximately 23% more expensive, while only 10% in bedrock, which is significantly lower than the 200% to 300% differentials reported in previous studies. We attribute this to the level of detail of our studies, the inclusion of ground conditions and conclude that our results help to dispel certain misconceptions about underground construction, which can contribute positively to urban sustainable development goals.