Life cycle assessment of hemp-lime concrete wall constructions: The impact of wall finish type and renewal regimes

Using sustainable building materials is one of the key methods for minimising the negative environmental impacts of the global construction industry. Bio-based buildings building materials, such as hemp-lime concrete, are considered more sustainable, as they make use of a renewable raw material and can sequester CO2 from the atmosphere. Studies have shown that hemp-lime concrete can have a favourable global warming potential, though the life cycle of building materials affects a wide variety of negative environmental phenomena that should also be considered. Studies examining the life cycle of hemp-lime concrete have so far primarily focused on the material itself. Though the exterior surface of a hemp-lime concrete wall needs to be protected and have a finish applied to it, few studies have considered the environmental impacts of coated hemp-lime concrete wall constructions. Using life cycle assessment methodology, through a wide range of environmental impact categories, the study analysed the environmental impacts of applying lime putty and sand coatings to a hemp-lime concrete wall in pessimistic, average and optimistic scenarios, It also compared the environmental impacts of four types of appropriate wall finishes and the impacts of applying varying finish renewal regimes in the use phase. It was found that applying lime putty and sand finishes to the exterior and interior surface of a hemp lime concrete wall increased the total global warming potential by 19.054–30.793 kgCO2eq and had a noticeable effect on all other impact categories. It was found that while no one finish type could be considered globally superior to the others, in a majority of circumstances applying lime-based coatings resulted in lower embodied environmental impacts, than applying a ventilated façade with timber cladding.