CLT offers high strength and the structural simplicity needed for high-efficiency construction, as well as a lighter environmental footprint than concrete or steel. It also provides numerous other benefits, including reduced waste, improved thermal performance and design versatility.
• Thermal performance and energy efficiency: CLT’s thermal performance is determined by its U-value, or coefficient of heat transfer, which relates to panel thickness. Thicker panels have lower U-values; they are better insulators and therefore require less insulation. Since CLT panels can be manufactured using CNC equipment to precise tolerances, panel joints also fit tighter, which results in better energy efficiency for the structure. Because the panels are solid, there is little potential for airflow through the system. As a result, interior temperatures of a finished CLT structure can be maintained with just one-third the normally required heating or cooling energy.
• Environmental advantages: Manufactured using wood from sustainably managed forests, CLT provides a number of environmental benefits in addition to its excellent thermal performance. Wood is the only major building material that grows naturally and is renewable, and life cycle assessment studies consistently show that wood outperforms steel and concrete in terms of embodied energy, air pollution and water pollution. It also has a lighter carbon footprint— because wood products continue to store carbon absorbed by the trees while growing, and wood manufacturing requires less energy and results in less greenhouse gas emissions.
• Less waste: CLT panels are manufactured for specific end-use applications, which results in little to no job site waste. Plus, manufacturers can reuse fabrication scraps for stairs and other architectural elements, or as biofuel.
• Fire protection: CLT’s thick cross-section provides valuable fire resistance because panels char slowly. Once formed, char protects the wood from further degradation. When used in Type IV construction, CLT assemblies also have fewer concealed spaces, which reduces a fire’s ability to spread undetected. In addition, CLT offers increased compartmentalization if used for interior walls.
• Seismic performance: Because of their dimensional stability and rigidity, CLT panels create an effective lateral load resisting system. Researchers have conducted extensive seismic testing on CLT and found panels to perform exceptionally well with no residual deformation, particularly in multi-story applications. In Japan, for example, a seven-story CLT building was tested on the world’s largest shake table. It survived 14 consecutive seismic events with almost no damage. CLT also offers good ductile behavior and energy dissipation.
• Acoustic performance: Test results show that because the mass of the wall contributes to acoustic performance, CLT building systems provide adequate noise control for both airborne and impact sound transmission. CLT building systems offer additional acoustic benefits because builders use sealant and other types of membranes to provide air tightness and improve sound insulation at the interfaces between the floor and wall plates.