Results from the simulated use of mass-timber construction to improve the thermal performance of lightweight residential buildings in Australia

Since Australia’s acknowledgement of climate change and its need to reduce greenhouse gas emitting activities, the national con-struction regulations have included residential thermal performance requirements. The improvement from no thermal performance regula-tion to the 5 Star minimum requirements could be met by increasing levels of floor, wall and ceiling insulation and improved glazing. However, the improvements required to achieve 6 Stars or more, may require the careful consideration of the type and placement of thermal capacitance. Traditionally, the materials selected to provide thermal capacitance include clay brick and concrete-based products. However, these are massive materials and have a relatively high embodied ener-gy. The use of mass-timber products within the built fabric may pro-vide improved thermal performance for a relatively small increase in embodied energy but also may significantly improve long-term carbon sequestration. This paper tests this hypothesis. House energy rating simulations were completed for 28 house plans located within two Australian climates. A comparative analysis of simulated heating and cooling requirements, embodied energy and carbon sequestration ex-amined the relative differences between the clay brick, concrete and mass-timber variations. In most cases the mass-timber systems pro-vided improved thermal performance, minor increases to embodied energy and significant increases in carbon sequestration.