- BACKGROUND OF STUDY
Sustainability in terms of the environment implies a natural resource balance. The core principle of “sustainability” is described as a “meeting the needs of the current generation without compromising the ability of future generation to meet their needs”, indicating a precautionary approach to those activities that effect the environment to prevent irreparable damage. However, construction is not an environmentally friendly process by nature, and it has become one essential part of sustainable issues. Resource utilization, the material manufacturing process, material transportation, and disposal of waste materials can potentially cause environmental problems. Greenhouse gas emissions, energy consumption, and depletion of resources are important factors that influence our built-environment. Sustainable construction must meet the goals for reducing energy consumption and greenhouse gas emissions, and using more renewable materials. Since the 1990s, the issues of sustainable buildings and sustainable building materials have been paid much attention to by scholars and governments around the world. Several green policies for green buildings and green materials have been proposed to address these issues. Within these policies, wood building structures are highly encouraged to be applied as green building structures as wood is regarded as an ecological green material, and it requires minimum treatment as well as minimum consumption of energy during the life cycle from the production to final disposal. There are several benefits of using wood material, one of which is carbon storage. Wood material contains 50% carbon during its growth, absorbing carbon dioxide in the air. Therefore, the more wood materials are used, the more carbon is stored, thus reducing the global warming effect. In addition, the effect of wood biomass substitution can decrease greenhouse gas emissions. It had been suggested that “exchanging coal for biomass wastes and residues is one of the lowest-cost, nearest-term options for reducing fossil CO2 emissions at existing power plants”. Research into fuel substitution in Sweden found that “the highest cross-price elastic ties can be found between wood fuel and non-gaseous fossil fuels (oil and coal), reflecting a relatively large substitution possibility”. In consequence, the use of wood material has a great advantage for reducing environmental problems.
However, wood resources are not sufficient in many land-limited countries or regions like Japan, South Korea, Taiwan, and so on. The domestic raw materials and products of wood can hardly meet the local demands from the construction industry, which requires a massive volume of wood materials. Therefore, the building construction industry in these countries or regions seeks to import wood from overseas. For instance, it is reported that approximately eight million to ten million cubic meters of wood are consumed in Taiwan every year, while the domestic supply amount of wood in Taiwan is only around fifty thousand cubic meters. The degree of self-sufficiency of wood in Taiwan is less than 1%, and almost 99% of wood used in the construction industry in Taiwan is imported from foreign regions, such as USA, Canada, Sweden, New Zealand, Australia, Brazil, Mainland China, and Malaysia. Hence, the identification of sustainable wood importing sources for these counties or regions plays a critical role in pursuing the sustainability of wood used in building construction.
Developing the building sector can provide substantial benefits to society; however the sector also contributes significantly to Humankind’s environmental footprint. Globally, for instance, buildings are responsible for more than 40% of total primary energy consumption and a third of total greenhouse gas (GHG) emissions (UNEP 2009, IEA 2013). The building sector normally accounts for 10-40% of Gross Domestic Product (GDP) and, at national level, usually accounts for 5-10% of employment (UNEP 2007 and 2009). Improving the environmental profile of buildings therefore has significant potential to stimulate both economic and social development, providing for the growth of new business, increasing employment and improving living conditions. In short, the environmental development of a building during its life cycle has an important role to play in terms of the sustainable development of our society, today and into the future (UNEP 2007 and 2009).
In this context, the life cycle energy use and environmental impacts of buildings have been intensively studied over the past few decades. Because of its dominance in the overall life cycle energy use, most attention has thus far been focussed on the energy used in a building’s functioning (operational energy) and associated impacts. Practical solutions for low energy buildings (e.g. a high level thermal insulation and air tightness of building envelopes; heat recovery ventilation system) have been intensively developed and as a result, operational energy demand and associated impacts have been significantly mitigated, leading to the introduction and development of low energy buildings. Although the operation phase is still responsible for the major part of the life cycle energy use of buildings, as a result of the aforementioned measures to improve operational energy efficiency, the relative importance of the energy used in other life cycle phases (e.g. material production phase (embodied energy)) is nowadays increasing.
A building is composed of a combination of many different products, which are made from various raw materials. The manufacture of building products is actually responsible for about 30% of annual global raw material consumption (UNEP 2008). In the building sector, raw materials are extracted, processed, transported, assembled with other products and finally disposed of (or reused/recycled) at the end of a building’s life. These processes all contribute to energy use and environmental impacts. Building material selection is, therefore, a significant factor in the development of sustainable construction. Against this background, wood and wood-based building products have lately attracted considerable attention as a promising construction material due to their unique environmental properties (e.g. renewability, reusability, carbon storage capacity, energy content, etc.). In fact, recently the development of sustainable wood construction has become a matter of public interest. In particular, the development of high-rise and large scale buildings from wood, replacing concrete and steel, has become a global trend, incorporating several aspects (e.g. environmental aspects, industrial potential). In addition, the life cycle assessment (LCA) of wood products and wood construction has nowadays also been frequently discussed.
Wood is an organic material, produced by a large number of woody plants and quite variable in properties. In fact, the term "wood is not much more definitive than the term "metal." Many species with differing characteristics are used in construction for many purposes. Compare for example balsa and birch, or redwood and rosewood. Wood is naturally grown, and the variability within a species, due to genetic and environmental influences, is substantial. In general, the variation for most wood properties (the ratio of highest to lowest for any property) is more than 2:l.
Prior to industrialization, buildings were traditionally constructed using locally sourced materials and manual labour. As a result, building artisans acquired deep knowledge of the materials that they used, resulting in proper material selection and maintenance that lead to efficient resource use and sustainable building life cycles (Murakami 2008). This would be the wisdom of traditional vernacular buildings cultivated before industrialization of the construction system, which is clearly an advantage compared to modern buildings. Although little scientific attention has so far been paid to vernacular architectures from an environmental aspect, there should be useful ideas to be taken from their solution (Murakami 2008, Kimura et al. 1999). A combination of traditional and modern building solutions could offer an interesting and profitable approach to the further development of sustainable modern buildings. As to building material selection, the idea that “the right material in the right place” should be particularly notable. The nature of materials was intrinsically understood from various aspects and suitable materials were used according to the function required, the location of use and so forth (Murakami 2008, Thoma 2003).
Unlike metals and fossil-fuel-based products (such as plastics), our forest resource is renewable and with proper management a flow of wood products can be maintained indefinitely. The importance of forest-based products to our economy and standard of living is hard to overemphasize— half of all major industrial raw materials we use in the United States come from forests. However, the sustainability of this resource requires forestry and harvesting practices that ensure the long-term health and diversity of our forests. Unfortunately, sustainable practices have not always been applied in the past, nor are they universally applied around the world today. Architects, product designers, material specifiers, and homeowners are increasingly asking for building products that are certified to be from a sustainable source. For the forest products sector, the result of this demand has been the formation of forest certification programs. These programs not only ensure that the forest resource is harvested in a sustainable fashion but also that issues of biodiversity, habitat protection, and indigenous peoples’ rights are included in land management plans.
Building construction has important role in sustainable development, it is not only due to participation in national economy, but it is due to the fact that constructed environment has great influence on life quality, comfort, security, health, etc.
Construction, maintenance and updating of constructed environment have potential effects on environment, and buildings consume most of unrecoverable resources and create great amount of waste, and buildings create half of the total carbon dioxide . The current building construction challenge is creating economical buildings that increase life quality while reducing social, economical and environmental effects. Achieving sustainability in architecture and construction is the goal emphasized more these days. There are many theoretical basics but some of them are not practical. Vernacular architecture due to some of characteristics has many sustainability aspects, but Architecture without sustainability as a serious challenge appeared after industrial revolution. The technology and its achievements are mainly considered, and architecture converts from "part of environment" to "separate from environment". So, architecture destroys environment and it would be changing and also noneconomic without adequate qualities. In result, new solutions should be proposed to benefit from technology in addition to interaction with environment. in this regard, sustainability approach presented and defined in building and architecture sector to improve these challenges.
- STATEMENT OF THE PROBLEM
A building requires assembling different materials through the process of construction. Some of these materials include concrete, timber (wood), steel and glass and so on. Energy is involved in the extraction of these raw materials, their processing and transportation from the factory to the construction site and their eventual placement. In most of the developing countries, Nigeria inclusive, there is a general dependence on fossil fuel for energy generation for these processes. This results in the emission of greenhouse gases such as carbon dioxide, sulphur dioxide, methane etc in the atmosphere resulting in the depletion of ozone layer thus causing global warming and by extension, climate change.
Some building materials such as steel, glass, concrete are manufactured from raw materials that their replacement require geological years while tree is continually being fell for construction work without due consideration for forestation, consequently the nature is over exploited resulting in environmental degradation, desertification, desert encroachment and imbalance in the ecosystem. Fewer trees mean more carbon dioxide in the atmosphere since plants absorb carbon dioxide and release oxygen into the atmosphere during photosynthesis. This has engendered the need to investigate the potentials of building materials that are comparatively sustainable, hence the topic “types of wood and Sustainability in Building and construction’’.
- AIMS AND OBJEVTIVES
The main of the study is to examine types of wood and sustainability in building and construction. Other specific objectives include:
- to determine between the relationship between types of wood and sustainability in building and construction.
- to examine the different types of wood.
- to Investigate the sustainability of wood as a building material.
- to offer recommendations that will enhance the sustainability of wood as a building material in Nigeria.
- RESEARCH QUESTION
- What is the relationship between types of wood and sustainability in building and construction?
- What are the different types of wood?
- How is the sustainability of wood as a building material?
- What are the recommendations that will enhance the sustainability of wood as a building material in Nigeria?
- STATEMENT OF RESEARCH HYPOTHESIS
1. H0: types of wood have no significant effect on sustainability in building and construction.
2. H1: types of wood have significant effect on sustainability in building and construction.
- SIGNIFICANCE OF STUDY
The study on the types of wood in sustainability and construction will be of immense benefit to the entire construction industry and the timber market in Nigeria. The study will explore the wood and the types of wood. The role of wood in the performance of the construction industry will be captured in this study. The study will educate the contractors in the construction industry on the best types of wood for effective construction. The study will serve as a repository of information to other researchers that desire to carry out similar research on the above topic. Finally the study will contribute to the body of the existing literature on the types of wood in sustainability and construction
- SCOPE OF STUDY
The study will cover types of wood and sustainability in building and construction.
- LINMITATION OF STUDY
1. Financial constraint- Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
2. Time constraint- The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.
- DEFINITION OF TERMS
Wood: the hard fibrous material that forms the main substance of the trunk or branches of a tree or shrub, used for fuel or timber.
Sustainability: Sustainability is the ability of a system to exist constantly at a cost, in a universe that evolves towards thermodynamic equilibrium, the state with maximum entropy. In the 21st century, it refers generally to the capacity for the biosphere and human civilization to coexist. The ability to be maintained at a certain rate or level.
Building: a structure with a roof and walls, such as a house or factory.
Construction: the action of building something, typically a large structure.