Chapter 10: Thermal performance of thermoactive continuous flight auger piles

Every year, the floor area of the European building stock increases by approximately 1%, resulting in additional energy consumption of over 4·5 Mt of oil equivalent (BPIE, 2011). At the same time, the European Union has ambitious carbon dioxide emissions reduction targets (EC, 2009) which are in conflict with such increases in demand. One approach for reducing both energy and carbon dioxide emissions from buildings is to adopt shallow ground energy systems, where ground heat exchangers are combined with a heat pump to improve energy efficiency, potentially reducing demand by around 75%, depending on the system coefficient of performance.

Further financial and embedded carbon economies can potentially be made by using the foundations piles of a building to host the heat exchanger part of the ground energy system, so called thermoactive piles or energy piles. This innovation was pioneered in the 1980s in Austria and Germany (Brandl, 2006). However, progress towards more global adoption of thermoactive piles and other geostructures has only taken place more recently (e.g. Barla and Perino, 2014; Laloui and Di Donna, 2012). This has triggered a renewed interest in thermoactive pile research, and for the first time, there has also been a focus on maximising the energy efficiency of these systems (Bozis et al., 2011; Cecinato and Loveridge, 2015; Gao et al., 2008; Wood et al., 2010).