Why Wood?

WHY SHOULD WE USE WOOD IN CONSTRUCTION?

Demet Sürücü, M.Sc. Forest Industry Engineer, Specialist

Wood is an exceptional construction material.

Wood is the only construction material with a renewable source, and it is a carbon store. Trees capture carbon while carrying out photosynthesis, the vital cycle that uses sunlight, water and CO2. Forests are carbon sinks; this cycle continues as trees grow and increase in diameter. As trees age, their capacity to store carbon decreases. Within the framework of sustainable forest management plans, trees need to be harvested and brought into the economy, and by constructing wooden buildings, wood continues to store carbon. One cubic meter of wood stores 1 ton of CO2. When a wooden wall covering 1 m² is built, a carbon storage capacity of approximately 52 kg is achieved. When a wooden wall replaces a similar concrete wall, approximately 100 kg of CO2 emissions caused by concrete production are also avoided. Harvesting wood renews forests and increases respect for and awareness of forests and wood.

Wood is the construction material that consumes the least energy during production. Compared to steel, reinforced concrete and other construction materials, less energy is consumed in producing structural wood. Wood industry facilities also use wood by-products such as bark and sawdust as fuel; both carbon cycle and energy consumption data encourage working with wood.

Wood is a recyclable construction material that contributes to the circular economy. The relatively low energy required to bring wood back into the economy after its service life as a construction material, together with its long lifespan, are among the reasons it is preferred as a building material. The fact that the oldest standing structure in Anatolia is the King's Tomb chamber at Gordion in Polatlı, Ankara, dating back to 800 BC, gives a brief idea of its lifespan as a building material.

Wood is a material that is highly resistant to earthquake loads and respectful of living beings' right to life. Wood is lightweight. It has a high load-bearing capacity relative to its weight. Thanks to this property, the seismic waves generated by earthquakes produce lower inertial forces, which makes wood the best construction material in earthquakes. For this reason, wood is the main structural material in almost 95% of residential buildings in regions of the world with high earthquake risk. Wood is resistant to seismic forces. Wood is five times lighter than concrete.

Wood is an industry that can be advanced through innovative technologies. Supported by technological developments, wood has ushered in a new timber age and has been designated the construction material of the 21st century. As a result of wood technologies, mass timber products such as Cross-Laminated Timber (CLT) and Glued Laminated Timber (GLT) have made multi-story wooden buildings possible. The 48-meter-high luxury residential project Treet, built in Bergen, Norway in 2015, the 18-story, 53-meter-high University of British Columbia student residence building, built in Vancouver, BC, Canada in 2017, and

multi-story buildings with heights ranging from 40 to 82 meters continue to be built in many countries such as the USA, Canada, Norway, Sweden and Japan, while existing laws, legislation and regulations are being revised.

Wood provides the time needed for people to leave a building unharmed in the event of a fire. For wood to burn, the temperature inside the wood must reach around 260 °C. Burning time may vary depending on the type and thickness of the wood and the production method of the engineered material. When wood burns, a char layer forms on the cross-section; since the part of the structural element beneath the char layer does not lose its load-bearing capacity even after the fire, designers and fire engineers are given the time needed to evacuate the people and other living beings inside the building. This is why buildings where large numbers of people gather, such as sports complexes, concert halls and airports, continue to be built with wood. Thanks to advancing technology, fire-retardant chemicals and architectural solutions, evacuation times of buildings can be calculated as 30, 60 and 90 minutes. The high expansion coefficient of steel causes structural collapse to occur rapidly. In multi-story wooden buildings, steel connection plates and screws are embedded in the wood or covered with intumescent strips, so that wood prevents the fire from reaching the steel.

Wood is the most suitable material for prefabrication. With wooden buildings that can be produced modularly, it is possible to promote a faster, waste-free construction sector. Especially in urban transformation projects, safe buildings can be constructed in a short time in densely populated areas. The saying "time is money" is proven once again with timber construction. Prefabrication is also a significant advantage in building permanent housing for disaster areas.

With its distinct advantages over other construction materials, and through hybrid solutions with materials such as reinforced concrete and steel, wood continues to rapidly strengthen its place in the construction industry as an economical building material.

In this process, wooden buildings must be designed correctly, calculations must be made accurately, and all designers must select wood according to the requirements of the place of use (earthquake, wind and similar effects, service life, etc.). Building livable cities is possible by reducing CO2 emissions and increasing organic construction material solutions. Scientific data and best practices from various countries have shown that, in the fight against the climate crisis, it is possible to increase structural wood production by establishing crisis-resilient forests. In Türkiye's Nationally Determined Contribution at the UN Climate Change Conferences, the targets of a 41% reduction in carbon dioxide emissions by 2030 and reaching "net zero" by 2053 were maintained for two consecutive years, at COP 27 held in Egypt in 2022 and COP 28 held in Dubai in 2023. To achieve these targets, Türkiye must immediately begin to find solutions by using wood in construction, the most effective way to decarbonize the built environment.