Several studies have revealed that, during the periods of national economic growth, construction activity grows at a faster rate than the economy as a whole. In many developing countries, the basic indicators of underdevelopment are related to gross inadequacies in shelter, infrastructure and amenity delivery systems which result from the constraints of the construction sector. Thus, the construction industry can be said to be the backbone of national economic and social development.
Despite the strategic importance of the construction sector, it still operates with major inadequacies in many countries. For example, construction costs are relatively high, basic inputs, particularly building materials, are scarce and expensive, the sector is import dependent amidst availability of unexploited indigenous resources. In short, the construction sectors outputs do not fulfil the demands for shelter and infrastructure especially the demands of low-income population.
There are several reasons for this anomaly but the most fundamental ones are: lack of sound planning and policies; lack of finance; and use of inappropriate and outdated technologies which are not suitable for local conditions, and are wasteful in terms of energy inputs. This publication addresses some of the latter problems.
The rapid pace of technological changes in the past couple of decades has radically impacted the nature of construction practices in developed countries and this has brought the technology-related issues in the forefront in various sectors including the building materials industries. Changing technological needs of the construction sector necessitates that the developing countries rectify their past deficiencies and enhance capacities to enable them to face the new challenges. Regardless of its level of development, each developing country should possess such capacities as to be able to monitor and assess the implications of the advances taking place around the world. It should further ensure that, the domestic construction sector is able to respond positively to changing technological environment.
In this context, absorption and adoption of innovative and appropriate technologies for developing human settlements in general, and for improving the construction sector in particular, play a vital role in any programme related to social and economic development. Adoption of innovative and appropriate technologies is not limited to setting up a mechanism to react to the above mentioned changes but also comprises the continuous acquisition of new information on construction processes in order to induct innovations.
No doubt information on available technological options is an important input for improving the performance of the construction industry, but final diffusion of technology goes beyond it and takes care of technological know-how, sources of technologies and finally establishes a mechanism and a framework for the modernization of existing industries.
The importance of the construction sector was recognized at HABITAT: United Nations Conference on Human Settlements, held in Vancouver, Canada in 1976 and the Commission on Human Settlements in its fifteen sessions over the past twenty years has underscored the significance of the sector by adopting special resolutions and by recommending selected programme areas to be implemented by UNCHS (Habitat). Owing to the vital role of the indigenous construction sector in the achievement of national economic and social goals, most of the activities of the Centre, in the construction sector, have focused on strengthening the domestic capacities of developing countries to enable them to meet the increasing demand of the construction sector outputs-housing and infrastructure facilities.
Agenda 21, adopted by the United Nations Conference on Environment and Development (UNCED), held in Rio de Janeiro, Brazil, in June 1992, has underscored the direct relationship between sustainable human settlements development and the sustainable construction-sector activities. In so doing, it has included a separate programme area entitled Promoting sustainable construction industry activities in its recommendations on Promoting sustainable human settlements (Chapter 7 of Agenda 21).
The basis for action for promoting sustainable construction activities as stated in Agenda 21 reads as follows:
The activities of the construction sector are vital to the achievement of the national socio-economic development goals of providing shelter, infrastructure and employment. However, they can be a major source of environmental damage through depletion of the natural resources base, degradation of fragile eco-zones, chemical pollution and the use of building materials harmful to human health
and the objective for these actions as stated in the Agenda reads:
The objectives are first, to adopt policies and technologies to exchange information on them in order to enable the construction sector to meet human settlements development goals while avoiding harmful side-effects on human health and on the biosphere, and, second, to enhance the employment-generation capacity of the construction sector. Governments should work in close collaboration with the private sector in achieving these objectives
Recognizing the crucial role of the construction-sector activities in providing shelter for millions of poor and low-income population, the Habitat Agenda of the Second United Nations Conference on Human Settlements (HABITAT II), held in Istanbul, Turkey in June 1996, has also included in its Global Plan of Action a distinct section on construction sector and has devised a comprehensive set of action areas to be taken by Governments and other stake holders in the sector.
It is worth mentioning that both Agenda 21 and the Habitat Agenda lay special emphasis on environmentally-sound construction practices to ensure sustainable use of natural resources; reduce the polluting impact of construction on the environment; reduce the cost of construction outputs in order to render them affordable to low-income population; and make the construction practices compatible with the local conditions (use of appropriate technologies). Both Agenda, among other things, stress the importance of improving energy efficiency and the application of low-energy, environmentally-sound and safe technologies in the construction.
The purpose of this publication, in line with the above mentioned recommendations, is to address some of the prevailing and critical setbacks of the construction sector in developing countries. It demonstrates how environmentally-sound construction practices can be developed and how and through which measures can the sector meet the local demands in a sustainable manner. Bearing in mind that energy is one of the costly and most vital input to the construction and the building materials industry and the fact that excessive use of energy increases the cost of production and causes environmental degradation, special emphasis has been given to energy related aspects of production. Attempt has been made to demonstrate and analyze different approaches and modalities on how energy use in the construction sector can be optimized and how high-energy content materials can be easily replaced with low-energy content materials for the purpose of low-cost housing construction.
The publication starts with an analysis of high-energy content materials such as cement, lime, bricks etc. and then proceeds to discuss recent innovations to traditional technologies such as soil construction, use of timber and bamboo, alternative cementitous materials and the use of organic and inorganic wastes in the construction. The publication also includes some energy efficient house design options namely: passive solar heating and natural cooling of buildings. Finally, the publication concludes with a chapter entitled: Strategies for optimizing the use of energy in construction. It should be mentioned here that, the technologies and any other information presented in this publication are inexhaustive. They can, however, serve as a basis for further study and research through the references and bibliographies given therein.