From Linear to Circular Cconomy; Using Hollow Piles to Reduce Embodied Carbon and Promote Pile ReuseÂ-Paper

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The paper argues that conventional piling follows a linear model: foundations are built, then often abandoned or removed when buildings are redeveloped. This is especially problematic in dense cities, where redevelopment can occur well before a pile’s intended 50-year design life. Reuse is discouraged by uncertainty about existing piles’ location, condition and capacity, alongside insurance, approval, cost and programme risks. Removing or avoiding piles can also create congestion, waste and disruption.<br /><br />The authors present the HIPER hollow pile, developed by Keltbray Piling and City, University of London, as a way to support a circular approach. Its reinforced-concrete annulus provides shaft resistance, while a base cap provides end bearing. A central void enables inspection and testing—including surveys and sampling while a building is still occupied—and can allow the pile to be extended if greater capacity is needed for a later development. Construction uses conventional piling methods and equipment.<br /><br />The hollow design reduces concrete use and associated transport emissions. The paper reports that a 900 mm HIPER pile uses 0.43 m³ of concrete per linear metre while providing structural capacity comparable to four 450 mm conventional piles, which use 1.13 m³—a concrete saving of about 60%. Using fewer, larger monopiles may also reduce pile-cap work and accelerate construction. Reusing a pile can further spread its embodied-carbon impact across successive developments.<br /><br />The authors conclude that easier access to reliable information is essential to overcome barriers to foundation reuse. Hollow piles offer a means to inspect, verify and potentially extend foundations, reducing waste and helping the deep foundations industry move toward lower-carbon, whole-life design.

Keywords

circular economy

piling

foundation reuse

HIPER hollow pile

deep foundations

embodied carbon

reduced concrete use

pile inspection

structural capacity

low-carbon construction