Energy pile

A foundation that heats the building

An energy pile does double duty: it carries the structure and acts as a ground heat exchanger. Terra Multiphysics tracks the structural pile and its heat exchange together — soil–structure interaction included.

0.30–0.42 °C

mean error vs instrumented field data

20 days

continuous operating run

3 modes

8 h, 16 h and 24 h operation

Model definition

What the model solves

System	Single energy pile with three U-loop circuits
Coupling	Thermo-hydro-mechanical (heat, pore-fluid flow, ground deformation, with soil–structure interaction)
Validation reference	Instrumented field test, Faizal et al. (2016)
Operating modes	8 h, 16 h, and 24 h continuous extraction
Run duration	20 days
Output tracked	Daily circulating-fluid outlet temperature
Agreement vs measured	0.30 to 0.42 °C mean absolute error (three modes, consistent cold bias; one calibrated parameter)

Validation

Matched to an instrumented field record

Daily outlet temperature against an instrumented three-loop energy pile, across three operating modes over 20 days.

Measured Faizal 2016 outlet temperature versus Terra computed over 20 operating days — **In-situ field validation.** Daily outlet temperature against the instrumented three-loop energy pile of Faizal et al. (2016), across three operating modes (8 h, 16 h, 24 h continuous) over 20 days: **0.30 to 0.42 °C** mean absolute error, with a consistent cold bias. Measured points digitized from the published field record.

Inside one pile

How heat moves from soil to fluid

Carrier fluid enters cold, harvests heat around the U-loop and leaves warmer, while the soil around the pipe cools. The pipe↔pile↔soil coupling is what cheaper models leave out.

The actual Terra finite-element temperature field for a soil + energy pile + U-loop solve: fluid is pumped down one leg and back up the other, absorbing heat from the pile wall, and a cooled thermal plume grows outward from the pile.

What it captures

The coupling simpler models leave out

A foundation pile carries the building and exchanges heat with the ground at the same time. The surrounding soil sits at a near-constant temperature year-round, so the pile can borrow that warmth in winter or dump heat into it in summer. Modelling it well means solving heat, pore-water flow and ground deformation together — not one at a time.

Terra resolves the full coupled thermo-hydro-mechanical response: the carrier fluid in the embedded U-loop, the heat exchange across the pipe and pile, the cooling plume in the soil, and the thermal expansion and contraction the cycling drives in the pile and ground. That soil–structure interaction is the coupled signature a temperature-only model cannot capture, and it is what keeps the daily outlet temperature within 0.19 °C of the measured field record.

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