The built environment makes a substantial proportional contribution to the overconsumption of natural resources, the production of air pollutants and greenhouse emissions, the Urban Heat Island effect, and has been strongly associated with decreased biodiversity. As the global community faces growing challenges in meeting the UN Sustainable Development Goals, innovative green technologies must be developed to maintain our quality of life in a sustainability-focused future. Such innovations include bio-based building materials and phytoremediation. As standalone technologies, hemp-concrete has impressive hygrothermal capabilities, maintaining temperature and humidity to comfortable levels; while green walls maintain temperature, humidity, and are capable of remediating common air pollutants. Both systems are carbon positive, and thus could make significant contributions to the move to net zero cities. However, there are limited studies comparing the services provided by hempcrete and green walls, nor of their potential for combined effects. We used four scaled-down buildings: three hempcrete structures – one cast-in-place, and two prefabricated, with one containing modular green walls, and one standard brick structure, exposed to Sydney’s industrial outdoor environment for several months to test these effects. Structure performance was compared for their effects on indoor ambient, outer and inner surface temperatures demonstrating high performance for both hempcrete, green walls, and the combined technology.
Based on the surface temperature data obtained, our results indicate that Cast-in-Place hempcrete has outstanding insulating properties, outperforming other building materials in mitigating extreme ambient temperatures. Furthermore, prefabricated hempcrete has relatively good insulating properties – slightly outperforming brick in mitigating indoor air temperatures. The hempcrete structure containing the green walls was marginally outperformed by brick, although still has contains the benefits of being carbon-positive and supporting biodiversity. As such, the insulative performance of Prefabricated and Cast-in-Place hempcrete generally outperformed brick as a building material, with impressive heat transfer mitigation from outdoors to indoors, providing a high performance, sustainable, carbon negative alternative material throughout a building’s lifecycle.