Towering 85 meters above the serene Norwegian countryside, Mjøstårnet stands as a remarkable testament to modern engineering. This 18-story structure, housing restaurants, apartments, and hotel rooms, might initially seem out of place amidst the rural skyline. However, a closer look reveals its harmonious integration with the surrounding forested farmlands. This is largely due to Mjøstårnet’s unique construction as the world’s tallest wooden building, crafted almost entirely from the trees of nearby forests.
For much of the 20th century, the idea of constructing a wooden building over six stories tall was deemed impossible. Traditional lumber, while strong against forces parallel to the wood’s grain, was vulnerable to perpendicular forces. This limitation meant wood lacked the tensile strength of steel and the compressive strength of concrete, both essential for supporting tall buildings and withstanding high-altitude winds.
The breakthrough came in the early 1890s with the invention of glue-laminated timber (glulam), followed by the development of cross-laminated timber (CLT) a century later. These engineered wood products begin as standard lumber, cut into smooth, uniform boards. In the case of CLT, these boards are glued in alternating orientations, with each layer set at 90 degrees to its neighbors. This configuration enhances the wood’s structural rigidity in all directions, allowing it to mimic concrete’s compressive strength and support loads up to 20 times heavier than traditional lumber.
Glulam, on the other hand, involves gluing boards in the same direction, forming massive beams with tensile strength comparable to steel. While not as versatile as CLT, glulam’s strength in one direction makes it ideal for load-bearing beams and columns. These innovations enable wood to compete with traditional materials, offering unique advantages.
At one-fifth the weight of concrete, CLT construction requires smaller cranes, foundations, and fewer workers. Unlike concrete, which demands a time-consuming casting and curing process, timber can be quickly shaped using computer-directed cutting machines. Additionally, engineered wood can be prefabricated in factories, creating standardized parts with clear assembly instructions, leading to faster and quieter construction with more biodegradable materials and less waste.
Once constructed, CLT and glulam buildings demonstrate resilience to natural disasters. Earthquakes can crack concrete, weakening structures, but cracked wood panels are easily replaced. In terms of fire safety, CLT’s outer layer chars at high temperatures, insulating inner layers for up to three hours, allowing ample evacuation time. Charred panels can be swapped out, unlike melted steel beams.
Beyond construction, CLT and glulam offer significant environmental benefits. Building construction accounts for 11% of annual global carbon emissions, with steel, concrete, iron, and glass production being major contributors. Timber, however, is a renewable resource that can be carbon-neutral if trees are replanted. Wood’s low thermal conductivity also facilitates energy-efficient heating and cooling.
Despite these advantages, CLT requires significantly more lumber than traditional wood construction, and neither CLT nor glulam matches the strength of steel or concrete in similar quantities. Even Mjøstårnet incorporates concrete slabs to reinforce its upper floors. A purely wooden structure may not yet support a 40-story building, the minimum height for a formal skyscraper. However, constructing buildings under 30 stories from wood could reduce their carbon footprint by over 25%.
As wooden buildings continue to rise, each contributes to the health of our urban environments, offering a sustainable alternative to traditional construction methods and paving the way for a greener future.
Research other wooden skyscrapers around the world and create a presentation. Include details such as their height, location, construction materials, and any unique features. Compare these buildings to Mjøstårnet and discuss how they contribute to sustainable architecture.
Using materials like balsa wood or cardboard, construct a small-scale model of a building using principles of CLT and glulam. Pay attention to the orientation of the layers and the structural integrity of your model. Present your model to the class, explaining the construction process and the benefits of using engineered wood.
Organize a debate on the pros and cons of using wood versus traditional materials like steel and concrete in skyscraper construction. Prepare arguments based on factors such as environmental impact, cost, durability, and safety. Engage in a structured debate with your classmates, presenting your points and counterpoints.
Analyze a case study of a natural disaster affecting a wooden building and a concrete or steel building. Compare the resilience and recovery process of each structure. Write a report summarizing your findings and discuss how engineered wood can improve disaster resilience in modern architecture.
Calculate the carbon footprint of constructing a hypothetical 20-story building using CLT and glulam versus traditional materials. Use available data on carbon emissions from material production and construction processes. Present your calculations and discuss how choosing engineered wood can contribute to reducing global carbon emissions.
Wood – A natural material derived from trees, commonly used in construction and manufacturing. – Wood is often chosen for building homes due to its strength and aesthetic appeal.
Construction – The process of building structures, such as homes, bridges, and roads. – The construction of the new community center will provide a space for local events and activities.
Timber – Wood that has been processed into beams and planks for use in building and carpentry. – The contractor selected high-quality timber to ensure the durability of the framework.
Sustainability – The ability to maintain ecological balance by avoiding depletion of natural resources. – Implementing sustainability practices in engineering can help reduce the environmental impact of new projects.
Architecture – The art and science of designing buildings and other physical structures. – The architecture of the new library incorporates green design principles to enhance energy efficiency.
Engineering – The application of scientific and mathematical principles to design and build structures, machines, and systems. – Engineering plays a crucial role in developing innovative solutions to environmental challenges.
Carbon – A chemical element that is a key component of all living organisms and is a major contributor to climate change when released in excess. – Reducing carbon emissions is essential for combating global warming and protecting the environment.
Emissions – Gases released into the atmosphere, often as a result of human activity, that can contribute to air pollution and climate change. – The factory implemented new technologies to lower its emissions and improve air quality.
Renewable – Resources that can be replenished naturally over time, such as solar, wind, and hydro energy. – Investing in renewable energy sources is vital for creating a sustainable future.
Resilience – The ability of a system or community to recover from disturbances or adapt to changes. – Building resilience in urban areas can help them withstand the impacts of climate change and natural disasters.
