ides excellent opportunities for re-use and, when harvested from certified sustainable forestry and properly recycled, it can serve as a carbon-neutral source of energy or construction material.
‘Timber’ is what we call wood that has been cut for use as building material. We tend to use both, wood and timber, interchangeably. Timber plays an important role in the debate about how our cities should evolve to accommodate what the government hopes will be an increasing population in coming years without irretrievably damaging the environment.
One cubic metre of wood stores around one ton of CO2, making timber a construction material that can impact positively on the environment. Generally, timber buildings require less primary energy consumption (‘primary energy’ is the energy form that has not been subjected to any transformation process; it is energy contained in raw fuels and other forms of energy received as input to a system; it can be non-renewable or renewable) and have a lower Global Warming Potential (GWP) than concrete or steel buildings (the difference can be 25 per cent or more). Ideally, shouldn’t our buildings be like trees and our cities like forests?
Let’s build the same building with half the resources! (Hermann Kaufmann) .
2.2. Forests, Trees, Wood Products and Carbon Sinks: Grown by the Sun, Timber Is Materialized Solar Energy and an Efficient CO2 Accumulator
Everything begins with the forest that provides the material and is a decisive climate factor if wood is sourced in a sustainable way from well-managed forests. Residential building construction with wood is now changing, focusing on green supply chains and resource-optimized engineered systems. Timber construction is an efficient method of CO2 storage, as long as the material is obtained using responsible methods of forest cultivation (plantations) and from a certified source that is not too far away (to avoid transport-generated greenhouse gases).
A tree produces oxygen, and absorbs over 1.4 metric tonnes of carbon for every ton of timber grown. One cubic metre of timber stores one tone of CO2. No doubt, steel and concrete are great building materials, until you consider their ecological footprint: 5 per cent of all GhG emissions worldwide come from concrete, while each ton of solid wood panels has sequestered around 1.6 tonnes of CO2. New engineered timber outperforms both concrete and steel: During manufacture a ton of steel emits 1.5 tonnes of carbon; and the production of a ton of cement emits over 1.1 tonnes of carbon. Fast growing softwoods will be the future, planted for laminating into large structural panels.
The aim is to evolve systems and designs in timber to tackle the significant negative environmental impact of buildings. Innovative uses of wood technology offer new ways of constructing efficient and affordable structures that demand fewer resources from the environment while maintaining functionality and aesthetic appeal.
Mid-rise urban infill projects—insertions within the existing urban fabric (not high-density and high-rise, but mid-rise, 4 to 10 storeys)—are gaining in popularity. The inner-city residential buildings of tomorrow will focus on construction speed, carbon emissions and weight reduction by using low-carbon lightweight construction systems and cladding; these prefabricated systems will increasingly use high-performance timber panels such as CLT panels, as these can be easily handled on-site. Building more mid-rise infill with timber is highly desirable, as carbon sequestered in trees is thus stored in wooden building components for the duration of the building’s life. This will enable us to turn buildings into ‘carbon sinks’, while avoiding GhG emissions, and increasing resource efficiency and buildings’ adaptability.
Recently conducted research on sustainable forest management, the lifecycle of wood products and the use of timber in infill construction has attracted the construction industry’s interest. For example, new findings report that instead of keeping wood growing in forests for hundreds of years, it is bene