Encyclopedia
Please note this is an old version of this entry, which may differ significantly from the current revision.
Subjects:
Engineering, Civil
The construction sector is currently responsible for over 30% of the consumption of natural resources and the release of solid waste and pollution into the environment. This situation is even more serious in closed communities such as islands, economically highly dependent on the outside world. One of the possible interventions to reverse this trend is the use of eco-sustainable construction materials such as wood, produced through supply chains with a low environmental impact. The local production of structural elements made of locally grown timber, besides the environmental benefits linked to wood properties, would bring ecological, social, and cultural advantages, such as better forest management and new job opportunities related to timber production, processing, and construction. These aspects are of paramount importance in isolated economies such as islands and become crucial in disadvantaged regions, such as the inner parts of Sardinia, currently prone to depopulation and a decline in rural land.
- sustainability
- building sector
- timber buildings
- short production chain
- circular economy
1. Introduction
Currently, the construction sector annually consumes an average 35% of resources—raw materials, water, and energy—and produces about 30% of the solid waste and pollution worldwide. This impact is incompatible with the concept of sustainability, which now permeates all sectors of human activity.
Sustainability is a complex concept, which concerns both the needs to be met and the capacities to be guaranteed over time, and the capital to be protected and enhanced, such as the environmental and human–social ones. The most widely recognized definition of sustainable development is reported in the report Our Common Future [1], commonly called the Brundtland Report, which identifies as sustainable the development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Based on this definition, the four pillars of sustainable development are identified as environmental sustainability, economic sustainability, social sustainability, and institutional sustainability, which protect and enhance the natural, economic, and human–social capitals with the aim of implying the maintenance of the quality and renewability of natural resources, guaranteeing job, income, and equally distributed well-being (safety, health, education, etc.) for the population, ensuring conditions of democracy, stability, and participation. Currently, climate change and environmental degradation pose a huge threat to Europe and the world. To overcome these challenges, the EU introduced the European Green Deal [2], a package of strategic initiatives that aims to put the EU on the path to a green transition, with the goal of achieving climate neutrality by 2050. The European Green Deal aims at transforming the EU into a modern, resource-efficient, and competitive economy by ensuring that no net greenhouse gas emissions are generated by 2050, and that economic growth is decoupled from use of resources. In this context, since sustainable development is clearly not compatible with the degradation of the environmental heritage and natural resources, it becomes mandatory for the construction sector to move toward a sustainable dimension. The turning point that can become the real driver of a process towards sustainability in the building sector is the circular economy model. The circular economy is based on cradle-to-cradle production and consumption models, which include the extension of the life cycle of products, the reduction of waste to a minimum, and the reintroduction of recovered materials into the economic cycle, according to the production–consumption–treatment–reuse chain, and in clear contrast to the current linear economic model, which instead acts according to the production–consumption–waste chain. As highlighted by the European Parliament [3], the circular economy would not only drastically reduce the EU’s carbon dioxide emissions but would also stimulate economic growth and create new job opportunities in Europe. It has been shown that the European New Circular Economy Action Plan (CEAP 2.0) would create 700,000 jobs across the EU by 2030 and the EU’s Gross Domestic Power (GDP) growth would increase by 0.5%. The circular economy model is particularly suitable in small and interconnected territorial realities such as islands, which face specific challenges due to their geographical and climatic conditions. These conditions result in the increase in the cost of living, fewer job opportunities, and overall lower economic results compared to continental ones. As stated by the European Commission [4], due to their small size and isolated energy systems, islands face a major challenge regarding energy supply. They typically depend on imported fossil fuels for electricity production, transportation, and heating, resulting in negative environmental and economic impacts. The transition toward a more sustainable energy supply, through the sustainable management of resources, would improve the efficiency, self-sufficiency, and level of protection of the islands’ environmental heritage. The use of local resources by the construction sector, therefore, appears to be a fundamental driver for sustainable and resilient economic growth and for the development of local skills and jobs for island communities. Especially in isolated communities, the high impact of the building sector and the prospects linked to the implementation of circular economies push actions toward two main directions: (i) the implementation of short production chains, and (ii) the use of eco-friendly, recyclable, locally available, and energy-efficient building materials.
The local dimension of the production chains entails various advantages in terms of sustainability. Easier logistics and faster delivery lead to better control over deliverables, and lower transport and storage costs lead to a reduction in the overall costs of logistics, thus increasing revenues. Companies are more aware of their environmental and social footprint and can more easily comply with local rules and ethical sourcing, and local sourcing leads to a reduction in carbon emissions of the supply chain process, thus reducing the environmental footprint. With all investments circulated locally, the short supply chain provides a great advantage to the local economy and to the individuals who live in the area.
Natural materials have found increasing interest over the years. According to Allied Market Research [5], the global green building materials market was valued at USD $237.3 billion in 2020, and is projected to reach USD $511.2 billion by 2030, growing at a CARG (compound annual growth rate) of 8.1% from 2021 to 2030. Natural building materials are recyclable products that promote the conservation of non-renewable resources and reduce the environmental impact of the production chain’s segments. The preeminent natural materials are those deriving from agro-forestry supply chains, eco-sustainable, renewable, recyclable, and with reduced LCA (Life Cycle Assessment) costs. The production of most natural materials, for example, involves a limited consumption of natural resources, energy, and carbon dioxide. In some cases, such as for wood, straw, and sheep wool, the impact can even be negative, as carbon dioxide can be sequestered and not dispersed into the environment. In this regard, in 2020, the European Commission launched the Renovation Wave Strategy [6], a program to improve the energy performance of buildings. One of the cornerstones of this strategy is the so-called life cycle thinking and circularity, that can be achieved by minimizing construction’s footprint by using resources in an efficient and circular way and transforming the construction sector into a sink of carbon dioxide, encouraging the use of green infrastructure and organic building materials able to store carbon, such as sustainably sourced timber. The main actions of the strategy include expanding the market for sustainable construction products and services, also resorting to new materials and nature-based solutions, and further developing the framework for eco-design to increase the offer of efficient products to be used in buildings and to promote their use.
Among natural load-bearing materials, timber is optimal from the point of view of environmental sustainability, as it is a naturally eco-friendly material characterized by appreciable mechanical and thermo-acoustic performance and ease of handling and installation. In Italy, the tradition linked to the use of wood in buildings was mostly limited to floors and roofs, but in recent decades there has been a renewed diffusion of wood in construction thanks also to the development of engineered products such as laminated timber. Nonetheless, almost all the wood used in construction is imported, with extremely negative consequences from the economic, environmental, and social points of view due to the costs, energy consumption, and pollution linked to transport, and the penalization of local development. In this context, the implementation of a short production chain for the use of locally grown timber in construction would certainly meet sustainability needs.
2. Sustainability of Timber as a Building Material
Wood, together with stone, is the oldest building material, and has been long and widely used due to its specific technical properties, availability in nature, renewability, and ease of processing and handling. Following industrialization, in some countries the use of wood has been downgraded or abandoned in favor of materials such as steel and reinforced concrete, but the notable technological evolution that has affected the wood engineering sector has determined the revamping of wood as a structural material in recent decades. From the point of view of environmental sustainability, the natural renewability of the raw material, the ability to extract carbon dioxide from the environment and store it for the entire service life of the material, even when it is transformed into a secondary and final product through manufacturing processes, and the recyclability, biodegradability, and the absence of toxic contents [7] represent advantages that allow timber to minimize its environmental impact. From the point of view of economic sustainability, timber is a light material, installed with dry connections and on small foundations, and easily prefabricated. These properties benefit timing, assembly, and logistics, and determine the general reduction of construction costs. From a performance point of view, timber can be used as a structural material, without reinforcing materials, in compressed elements such as pillars, bent elements such as beams, and stretched elements such as tie rods, unlike what happens with concrete and masonry. This is due to timber’s appreciable mechanical strength both in compression and in tension, which makes it an excellent competitor even for modern steel or reinforced concrete structures. Timber is also characterized by natural hygroscopicity, high thermal inertia, and low conductivity, therefore contributing to environmental comfort [8,9]. Owing to these positive issues, the wood industry is constantly expanding in Europe. In Italy, the timber construction sector is growing, and today, the turnover of the timber construction industry exceeds 1 billion euros, marking +33% compared to 2020, and Italy is currently the third European manufacturer of prefabricated timber buildings [10]. The spread of timber in the construction sector is favored by the production and development of laminated timber, an engineered wood that combines the characteristics of industrial products subject to quality control, such as high and constant performance and reliability, with the intrinsic advantages of a natural material. The main structural product in laminated timber is the GLT (Glue-Laminated Timber) beam, composed of overlapping boards glued in the direction of the grain (Figure 1).
Figure 1. Glue-Laminated Timber beams.
To produce GLT, boards cut from fresh logs and then artificially dried are used, selected according to the proper mechanical strength grading. The boards undergo an initial check that identifies their defects (knots, clusters of knots, resin pockets, grain deviation, deformations) and, in the event of exceeding the threshold values defined by the standards, the defective part is eliminated by truncation. The boards reclaimed from defects undergo a finger jointing and then pass to planing, and finally, to gluing. This production process ensures that the final product has superior mechanical characteristics compared to the parental solid wood. A further evolution of laminated timber technology is Cross-Laminated Timber (CLT), manufactured by superimposing layers of boards orthogonal to each other (Figure 2). The typical effects of wood anisotropy are attenuated by the cross-layer configuration, which also allows the use of CLT as a load-bearing element both in vertical structures such as walls and in horizontal ones such as floors and roofs. The benefits brought by the cross-layer configuration to the mechanical characteristics of the CLT also allow the use of wood species with poor mechanical properties. This has a positive impact in terms of sustainability, as it favors the use of local wood species that have mechanical characteristics lesser than those of Central Europe species traditionally used in the production of laminated timber [11,12]. CLT is very suitable for prefabrication, as it allows most elements to be produced in the factory and essentially only the connections to be left to construction site operations.
Figure 2. Cross-Laminated Timber panel.
3. Timber Production Chain in Sardinia (Italy)
Despite the positive market trend, the advanced technological solutions, and the availability of raw materials, with the Italian forestry area being over 35% of the total territory, among EU countries, Italy is the least self-sufficient in the supply of wood raw material, producing less than one-third of its needs. Dependence on foreign countries entails a highly unfavorable economic balance for the wood construction products, such as logs and sawn wood, veneers, panels, and semi-finished and finished products, which is overall positive only thanks to the Italian furniture industry and the considerable added value generated by this sector. Italy imports two-thirds of its needs from Austria, France, Switzerland, and Germany, and is the leading European importer of industrial timber, the leading world importer of firewood, and the fourth world importer of wood chips and scrap wood. Sardinia is in line with this trend, also due to the further handicap of its insular condition. The level of harvesting of Italian forests is one of the lowest in the EU, being less than 25% of the annual increase, compared to the EU average of 65%. Overall, the supply of Italian wood is quantitatively low, characterized by qualitative and quantitative inhomogeneity and generally not directed toward adequate technological and economic valorization [13].
In line with the general Italian trend, Sardinia Island (Italy) is currently witnessing a continuous growth of the timber construction market, evidenced by the growing number of local companies operating in the sectors of assembly and marketing of timber buildings. Furthermore, Sardinia is characterized by a forest area equal to approximately 40–60% of its total surface area, with a prevalence of Oak and Eucalyptus among the broadleaved trees and Aleppo Pine, Stone Pine, Radiata Pine, and Corsican Pine among the conifers [14]. Despite these aspects, currently, no structural timber production chain is present in Sardinia, and the wood used in timber buildings is almost 100% imported.
This entry is adapted from the peer-reviewed paper 10.3390/su152014815
This entry is offline, you can click here to edit this entry!
