Application of Vegetal Concrete for Carbon-Neutral Built Environment

Abstract

To maintain the thermal comfort, buildings consume about 40% of the total energy produced in most of the countries. Thus, they are one of the largest contributors to the global greenhouse gas emissions and the associated climate change. Emissions from the built environment originate from three sub-sources: construction, operation, and demolition. To reduce the embodied energy of construction materials, operation energy of buildings, and energy required to dismantle the buildings at the end of their life cycle, the use of materials made from crop residues and agroforestry wastes seems to be a viable option. Lightweight concrete made of crop residues such as hemp, jute, sisal, flax, nettle, and pigeon pea in the form of aggregates is also called “vegetal concrete.” These aggregates are embedded in a cementitious matrix. Few examples of vegetal concrete are lime hemp concrete, cork-cement composites, lime stabilized straw bale, flax-lime concrete, and cement straw boards/panels. Because of their source, these biomass-based building materials are considered to be carbon negative. In addition, carbon sequestration takes place during various stages of their lifespan. The other advantages with vegetal concretes are their excellent thermal insulation property and a favorable hygrothermal behavior that improves thermal comfort and thereby reduces energy consumption in buildings. This chapter reports the availability and suitability of various crop residues, the types of vegetal concrete being developed, the carbon footprint of vegetal concrete materials, and their impact on energy consumption in buildings throughout the three phases: construction, operation, and demolition. Comparisons with other applications for crop residues are also drawn, and the second-order effects of manufacturing and application of vegetal concrete are discussed in the chapter.