Built Environment is the slogan
The need to protect the built environment in the face of infrastructural development has been the objective of many nations, regardless of their economy. Concerted efforts are being made to counter the negative impact of human activities on the environment. Some industries are beginning to reduce the amount of fossil fuels consumed or find alternative fuels and design new techniques aimed at reducing carbon dioxide emissions.
Nevertheless, if any success is to be achieved, the construction sector must focus on finding solutions.
The construction sector is a major emitter of greenhouse gases. During construction activities, large quantities of natural resources are consumed. Water is used extensively, much waste is generated, and a wide range of ecosystems is destroyed.
Due to the negative impact of the construction sector on the environment, there are increasing demands from the public to ensure sustainable construction – requiring new methodology for building design, construction, maintenance, regeneration and conservation. One aspect to be considered in the context of sustainable construction is the environmental impact from the extraction and production of the materials used.
Nigeria offers the greatest construction opportunities in Africa
If the growth rate of the construction sector in Nigeria (regarded to be 18.08%), is anything to go by, then it has the potential to surpass China by the year 2020. Though contributing about 3.2% of Gross Domestic Product (GDP), the construction industry is a multibillion dollar business in Nigeria.
A survey by the Nigerian National Bureau of Statistics (NNBS) on the cost of construction materials consumed between 2010 and 2012 indicates that, apart from a slight drop in cost of gravel/granite between 2010 and 2011, there is a steady growth occasioned by increased construction activities in the country (Figure 1).
Presently, massive construction works are on-going in every part of the country. A few of the notable edifices that have been constructed in the last three years are shown in Figure 2. What could have been responsible for this rapid growth in construction in Nigeria?
The need to provide infrastructural facilities for the teeming population is one of the major impetuses for the unprecedented construction activities going on in the country. Secondly, Nigeria is blessed with natural construction materials such as granite, sand, water, timber etc., including large deposit of calcium carbonate, a major raw material in cement manufacture.
Currently, the annual cement production capacity in the country is put at 29.75 million metric tonnes (mmt) with great potential to increase. Another catalyst that aids the construction sector is the ever-increasing size of a middle class with the expectation that everyone must have his/her own building.
Figure 1: Cost of materials input in construction in million USD
Despite the giant strides made by the government to provide the infrastructure needed, there is still a huge gap between demand and supply. For instance, housing deficit has been widely reported as 16 – 18 million units, with an estimated N60 trillion (about USD266.7 billion) needed to bridge the gap. Recently, the Federal Government created a new Ministry of Lands, Housing and Urban Development with a mandate to provide about 54,500 housing units across the country.
The road network is also grossly inadequate with only 30% paved. In tackling this menace the government resolved to disburse a sum of N921.4 billion (USD4.1 billion) in addition to N1.4 trillion (USD 6.2 billion) that has been spent to complete about 195 road projects, which were under construction across the country. Several other areas of infrastructural development require similar attention, such as waterways, airports and railways, for the country to achieve the goals of Vision 20:2020.
All these are indicators of the fact Nigeria could potentially be one of the biggest construction markets in the world.
Is the Nigerian construction sector sustainable?
Sustainable construction means responsible supply, operation and maintenance of buildings (or any other infrastructure) that meet the needs of their owners and users over their lifespan with minimal unfavourable environmental impacts, while encouraging economic, social and cultural progress. This definition was developed during the Marrakech Task Force Sustainable Building and Construction workshops in 2007.
But to what extent has the construction sector in Nigeria fulfilled the criteria of this definition? Have all the buildings in Nigeria served their intended use within their expected lifespan? Does the construction sector minimise its negative impact on the environment?
Reports of incessant building collapses in the country are indicators that much is still needed in sustaining our construction activity. Where buildings collapse, rubble from the collapsed building is disposed of indiscriminately, posing a threat to the environment.
The Nigerian construction sector still relies heavily on traditional construction materials which are not sustainable as wide expanses of the ecosystem are destroyed due to extraction and production of materials used for construction. Figure 3 shows the impact of quarrying of granite and sand on the environment as well as the air pollution resulting from cement production.
Unless drastic efforts are made to counter the negative aspects of our construction practices, more harm than good will come from our quest for infrastructural development.
Sustainable construction materials are available in abundance in Nigeria
The cost of construction materials is increasing daily because of high demand, scarcity of raw materials, and high energy costs. From the standpoint of energy saving and conservation of natural resources, the use of alternative construction materials is now of global interest. Different solid wastes, generated in large quantities by industry and agriculture, are being used as full or partial replacement for conventional materials in many developed countries.
This includes wastes such as fly ash and rice husk ash which are used as pozzolans to partially replace cement in concrete.
Being an agrarian country, Nigeria generates extremely large quantities of agricultural waste, the effective disposal of which is a major challenge. Urbanisation and industrialisation has also created unprecedented amounts of industrial waste. For instance, Nigeria is the biggest producer of cassava in the world.
In processing cassava either for industrial or domestic uses, large quantities of cassava peels are produced. Similarly, corn cobs, Bambara groundnut shells, and coconut shells are agricultural wastes, the ashes of which research has shown, are potentially pozzolanic and could be used as a partial cement replacement.
Furthermore, in Nigeria’s industrialisation drive steel mill industries have been established, which produce steel slag as a by-product. Steel slag, along with building rubble, is lying unutilised while studies have shown that these materials could be used as aggregates in concrete production.
Why is Nigeria not tapping these resources?
Unlike in most developed countries, Nigeria has no policy on the use of wastes in construction. Where any policies exist, they have not been enforced. However, it appears that Nigerian Building and Road Research Institute (NBRRI) is a making a concerted effort to address the problem.
The NBRRI launched cement-stabilised brick technology with which it recently built classrooms at the Pastoral Resolved Centre of the National Commission for Nomadic Education (NCNE). The use of waste materials reduced the cost of construction dramatically. Nevertheless, more needs to be done to utilise available alternative construction materials.
Nigeria must wake up to ensure sustainable construction
For Nigeria to ensure sustainable construction a holistic approach must be adopted. The government, as a matter of urgency, must create appropriate means for implementation of research results while a realistic national policy for scientific research in the sustainable construction materials must be developed.
A synergy between the universities where sustainable materials are being researched and their counterparts, the research institutes, should be encouraged. It is hoped that if everything necessary is done, Nigeria could be point of reference in sustainable construction.
More information from the author on [email protected], Tel:+234(0)7036439726
