ficial if the wood is regularly harvested and used in construction (to increasingly replace concrete or steel); in this way, carbon dioxide can be removed from the atmosphere . Only a small portion of Australia’s forests are ‘carbon dense’; most are lower density open forest or woodland. A considerable proportion is regrowth from previous harvesting and over 90 per cent of timber production is concentrated in those areas.
Lippke and his team have identified a number of possibilities for the use of engineered timber panels to replace fossil fuel-utilizing construction systems of reinforced concrete and structural steel. According to their findings, sustainably managed forest plantations in practice offer a two-way flow of carbon dioxide: they absorb carbon dioxide during their growth and when the tree dies and decays, falls back or burns, the carbon returns to the atmosphere; thus the plantation remains carbon neutral . For instance, Lippke’s team calculated that the use of engineered wood joists (weighing around one metric ton) in place of steel floor joists reduces CO2 emissions by approximately 10 tonnes. In another example, the use of wood flooring in place of concrete slab flooring reduced the CO2 emission level to 3.5 tonnes for every ton of wood utilized. Therefore, they recommend: plantation of rapid growth tree species, cropping the wood before the trees become less active, utilizing them in place of steel or concrete in construction, or using the wood as biomass to produce energy or bio-fuels to replace fossil fuels. This suggests that a detailed evaluation of each forest will have to be done, as older forests are slower in their absorption of carbon dioxide, but continue to offer numerous other ecological benefits (e.g. high biodiversity). Life cycle analysis will help to compare the different options’ carbon footprints.
Timber is one of few materials that have the capacity to store carbon (other materials, such as straw and bamboo can also store carbon), which means that CLT construction systems are an opportunity to turn building structures into ‘carbon sinks’. Contemporary technology has changed both the way in which timber buildings are converted and assembled , and how these can be protected against fire, insects and decay [34,35]. Wood is one of the oldest construction materials and one of the most utilized worldwide (more than steel and concrete) in construction . Given its carbon sequestration capacity, wood might well be the construction material of the twenty-first century. Engineered timber from managed forestry, from independently certified sources (i.e., PEFC, FSC), are likely to revolutionize the construction industry and become the material that makes sustainable construction in future possible [37,38,39].
The energy budgets of products and buildings made of wood show that they may use less energy over their total life cycle (manufacture, use, maintenance and disposal) than can be recovered from the waste products of their production and from their recycling potential at the end of their life cycle: they are energy-positive. No other construction material is so comprehensively energy-efficient and therefore climate effective as wood. (Wegener, Pahler and Tratzmiller, p. 4) .
3. What Is Solid Wood Panel Construction and What Advantages Does It Bring?
According to the Timber Development Association of Australia , a cross-laminated timber (CLT) construction system is a structural wood panel system fabricated by bonding together large timber boards with structural adhesives, alternating the grain directions of each layer, to produce a solid, load-bearing timber panel with each layer of the panel alternating between longitudinal and transverse lamellae. CLT is not just a ‘product’, it’s a building system. It has now become a recognised construction system increasingly used in Europe as an alternative to steel and concrete.
Large-format solid timber panels are engineered wood products used as massive load-bearing walls and floor slabs. First developed in Switzerland, Germany and Austria, CLT panels are