A systematic literature review on the thermal behaviour of building elements constructed through 3D concrete printing (3DCP)

3D concrete printing (3DCP) is increasingly used in construction due to its high speed, low waste, and geometric freedom capabilities. Researchers have signaled that 3DCP can help achieve long desired sustainability in the construction industry. Understanding the thermal behaviour of 3DCP based building elements could play a crucial role in attaining an energy efficient envelope, yet research on assessing the thermal behaviour of printed elements remains limited. This systematic literature review of records published between 2013 to 2023, provides a comprehensive overview of the thermal behaviour of several 3DCP-based materials and the important factors affecting heat transfer properties. The most common 3DCP materials with optimal thermal, mechanical and structural properties are geopolymers, phase change materials, fiber reinforced composites, polymer lattices, lightweight and foam concrete. Experimental analysis of heat transfer characteristics shows that 3DCP elements exhibit anisotropic tendencies due to a layered design and a specific fiber orientation. Thermal behaviour is expressed in terms of thermal conductivity (K value, W/mK) and overall heat transfer co-efficient (U value, W/m). Infill rate and pattern, relative density, printing speed, additive infusion, cavity fillers, geometric configurations, mix composition, surface irregularities, material fillers, and structural inhomogeneities are the main factors affecting the thermal behaviour of building elements. Effective control of the printing parameters, geometric optimization, and the correct balance of additives and fillers in the mix have the potential to lower thermal conductivity, providing an effective insulation blanket. Moreover, future research efforts could use standard techniques to interpret the thermal behaviour and the underlying factors.