3D printing for energy optimization of building envelope - Experimental results.

The building sector is a major contributor to the world's energy consumption, exhibiting an ever-increasing trend. Heat losses through the building envelope constitute the most significant factor. Furthermore, the construction process has seen limited technological advancements in recent years, remaining heavily reliant on manual labor. Additive manufacturing emerges as a promising approach, with applications in the building sector on the rise. However, research on the thermal performance of 3D-printed components remains limited. Despite its recent introduction in the construction industry, 3D printing has yet to attain a level of maturity commensurate with other established methods. This paper aims to reduce this gap by analyzing 3D-printed blocks from a heat transfer perspective. The article introduces two key innovations. Firstly, it explores the design of various internal geometries and air gaps aimed at minimizing heat flux exchange between block surfaces. Secondly, it presents an experimental study conducted with a custom-designed setup tailored for testing 3D printed blocks. The blocks are constructed using recyclable plastic material and feature different internal geometries based on hexagonal cells. While the plan size of the cells remains consistent, their vertical structures vary as follows: 1) Block 1: Hexagonal air cavities without horizontal partitions. 2) Block 2: Hexagonal air cavities with three horizontal partitions, dividing the cells vertically into four parts. 3) Block 3: Honeycomb structure characterized by three horizontal partitions and staggering along the vertical axis. Their performance was experimentally evaluated using the Hot Box method, heat flow meter sensors, and infrared thermography. The results demonstrated reductions of up to 11.5 % in terms of thermal transmittance (U-value) with the inclusion of horizontal partitions. Starting from a U-value of 1.22 ± 0.04 W/m