Sustainable phase change material solutions for buildings: A study on the potential of vegetable butters

This paper explores the characteristics of twelve types of vegetable butters, including their chemical composition, density, latent heat, and thermal conductivity, using various experimental methods. All these butters are composed of three categories of fatty acids in varying proportions: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). SFAs are the dominant fatty acids, accounting for between 30 % w /w and 89 % w/w of the total composition. However, in these complex lipid systems, the thermal behaviour cannot be interpreted solely on the basis of fatty acid composition and reflects the combined effects of fatty acid distribution, triacylglycerol architecture and polymorphism. For instance, the latent heat storage capacities of these different butters, which range from 90 to 142 kJ/kg, are closely tied to their chemical composition. Both melting and crystallisation temperatures also differ significantly from one species to another, while all studied butters demonstrate an apparent thermal stability temperature higher than 285 °C. Of the vegetable butters evaluated in this study, tucuma, murumuru, and cocoa butters show excellent potential for use as PCMs in building applications to improve thermal comfort in temperate climates, due to their favourable melting/crystallisation temperatures and associated enthalpies. However, they are not suitable for use in tropical areas, where mango butter is a more appropriate option. • Vegetable butters show diverse thermal responses linked to their lipid structure. • Thermal behaviour arises from both fatty acid composition and triacylglycerol polymorphism. • Fatty acid chain length and unsaturation control first-order phase change trends. • Polymorphic TAG organisation explains multi-peak melting and crystallisation behaviour. • Climate-dependent selection is required to ensure reliable PCM cycling in buildings.