Hempcrete building performance in mild and cold climates: Integrated analysis of carbon footprint, energy, and indoor thermal and moisture buffering

Abstract

The use of hempcrete as a bio-based alternative to conventional building materials was investigated through a building life cycle carbon footprint analysis of a conventional wood-frame enclosure and a hempcrete enclosure. Embodied emissions were determined using the Athena Impact Estimator. An in-house developed whole building hygrothermal model was validated using experimental data and then used to assess the operational energy including the dynamic interaction of thermal and moisture buffering with building heating and cooling loads.The higher thermal mass of hempcrete was shown to increase heating energy consumption and reduce cooling energy consumption due to a reduction in solar heat gain. Therefore, for the mild and cold climates studied here, cooling energy savings were mostly overtaken by increased heating energy consumption. The difference in energy performance was minimal compared to the savings in embodied emissions for the building life cycle carbon footprint, which showed a 23.2% and 9.9% reduction in emissions for the hempcrete building with a 50-year lifespan.Due to the high moisture capacity of hempcrete, ignoring the moisture-dependency of thermal conductivity can result in underestimation of energy consumption. Moisture buffering had little effect on energy performance, however, it can greatly reduce condensation risk, thereby improving IAQ and durability.