Experimental investigation of novel bio-composite with integrated phase change materials (PCM) for enhanced energy saving in buildings

Abstract

The construction sector contributes to over 35 % of the garbage and emissions of greenhouse gases in the European Union. The importance of renewable natural resources in producing low-energy, environmentally friendly products is increasing. The possibility of creating alternative building materials, such as bio-composites, is expanding. This study reveals the possibility of modifying native potato starch (PS) subjected to treatment with sodium silicate solution (SS), glycerol (GL) and phase change materials (PCM) in purpose to improve hemp shive bio-aggregate based composite mechanical and heat storage properties. Directly using SS and GL as starch modifying generally saves materials and energy necessary for hemp shive pre-treatment (washing, preparing, drying, saving working hours) and does not produce waste. The bio-composite can be made stronger by as much as twofold, and its water absorption can be reduced by up to 27 % by modifying the starch binder and applying a heat treatment procedure. Adding PCM may increase the samples‘ heat capacity by up to 35 %. At the same time, it prevents swelling, reduces water absorption, and allows for increased mechanical strength, satisfying its use as a construction thermal insulation material. The effect of three different preheating temperatures (i.e., 60, 40, and 35 °C) was studied, imitating possible summer temperatures reached on the building wall in the bio-composites with PCM. The time to reach PCM phase transition temperatures of 27 and 23 °C depends on preheating temperature. Preheating at higher temperatures positively influences PCM effectivity in the bio-composite.