Exploring te potential of hardwood for building construction to reduce embodied GHG emissions

This study investigates the potential of hardwood as a complementary structural material for reducing embodied greenhouse gas (eGHG) emissions in buildings, responding to the growing interest of substituting concrete. Historically, operational emissions have been significantly reduced through improved thermal insulation and renewable energy integration, shifting attention toward eGHG emissions. While softwood is chosen to replace concrete in structural applications, resource limitations restrict its scalability. This research quantitatively assesses hardwood as a complementary alternative. The methodology involves identifying representative building typologies in Switzerland from energy performance databases and selecting two contemporary objects as benchmark case studies. Life cycle assessments (LCA) of these buildings establish eGHG emissions benchmarks. Timber alternatives, employing both soft- and hardwood, are developed according to practical construction requirements, structural safety, serviceability (vibration control), and fire safety criteria. Comparative LCAs of these timber typologies, based on Swiss standards (SIA 2032 and KBOB database), quantify potential eGHG emission reductions in comparison to concrete construction. The results reveal that timber substitutions consistently lower eGHG emissions compared to concrete. Although hardwood generates 20-100% higher emissions at the element production level, due to its density and processing demands, building-level analyses demonstrate comparable eGHG emissions reductions for both timber types. Multi-box slab elements significantly outperform traditional joist construction in material efficiency, minimizing slab thickness and related building height. Furthermore, structural over-dimensioning for fire safety proves more environmentally advantageous than protection panels when fire safety requirements are limited. Overall, hardwood emerges as a credible solution to complement timber typologies, enabling substantial eGHG emission reductions.