The concentration of the world’s population in urban centers has led to important processes of urbanization and construction, which on many occasions have exceeded the capacity of the urban land where they are located. This has characterized a set of conditions that are closely linked to various types of environmental impact, having special relevance the reduction and pollution of water sources, the critical conditions of environmental sanitation, the loss of natural habitats and biodiversity, high rates of solid waste generation and general deterioration of environmental conditions in cities.
In order to contextualize the environment in which these urban processes operate. This document presents an approach to the world panorama related to energy, water, materials and land in housing. And, the impact on planetary boundaries, specifically the loss of the integrity of the biosphere (loss and extinction of biodiversity), by the architecture and construction industry.
According to the UN, it is estimated that worldwide 41% of available energy is consumed between the residential and commercial sectors. This high energy consumption directly affects the environment; through the use of non-renewable resources such as oil, gas and coal, which generate high emissions of CO2 and other greenhouse gases (GHG), contributing to pollution of the planet. It is estimated that between 7 and 9% of total global carbon dioxide emissions come directly from housing use. International energy consumption reports state that fossil fuels (oil, coal and gas) continue to form the basis of primary energy consumption in the world. In 2008, fossil fuels accounted for 88.1% of the world’s total consumption of energy sources, a slight decrease compared to 2007.
The fastest growing energy source in 2007 was coal with 3.4%, followed by hydroelectricity with 3.1%, then gas with 2.8%, while oil decreased 0.29% and nuclear showed a decrease of 0.45%. Of the total energy consumption, 22% corresponds to the residential sector and 19% to the commercial sector. Having as a base world population, a figure higher than six billion inhabitants and whose trend is to exceed nine billion in 2050, according to global statistical projections.
According to a report on the forecast of world energy consumption until 2030, prepared by the Energy Information Administration (EIA), in terms of CO2 emissions, this will grow 39% in the period, going from 29 billion metric tons to 40.4 billion by 2030. From the environmental point of view, the increase in CO2 emissions continues; its estimate reaches a total of 8,565 metric tons in 2008, and its percentage distribution by source is 20.7% for gas, 34.8% for oil and 44.5% for coal. CO2 emissions related to fossil fuels are also expected to decrease as the demands of developed and emerging countries are reduced.
The analysis of the current state of water and the anthropogenic effects on this resource must be framed in the natural availability of water on the planet. It is estimated that water covers 71% of the land surface, located mainly in the seas and oceans where 97% of total water is concentrated and the other 3% of fresh water; distributed among glaciers and polar caps containing 2.06%, underground deposits and continental glaciers with 0.93%, and the remaining 0.001% is distributed in decreasing order among lakes, soil moisture, atmosphere, reservoirs and rivers.
The situation of shortage or deficit in the supply of drinking water in the world is critical, according to the UNESCO, 1.1 billion people in the world lack this service and 2.4 billion lack adequate water sanitation. This reality was addressed during the 5th World Water Forum in Istanbul (Turkey) on 16 March 2009. Based on the data presented in the Third World Water Development Report (WWDR-3), “ensuring environmental sustainability” was set as a priority objective and the goal was to halve the proportion of people without access to safe drinking water by 2015; this goal was impossible to achieve.
On the other hand, the Food and Agriculture Organization of the United Nations (FAO), presents data on the distribution of water according to its different uses; finding that 93% of water is destined for agriculture, 4% for the architecture and construction industry, and only 3% for domestic consumption. This same report reveals that 25% of the total population of developing countries does not have access to drinking water and that 90% of polluted water is discharged directly into rivers, lakes, lagoons or the sea. This increases the serious problem of scarcity and generates high impacts on human health, reaching the conclusion that about 80% of the ailments and 33% of the deaths are derived from the crisis of shortage of drinking water; this situation varies a little in urban areas, since its deficit of coverage in aqueduct is 27.5% and 36.9% in sewerage.
In fact, the availability of drinking water has been reduced in an accelerated way both in the reserves of underground aquifers and in surface currents. This is partly due to the contamination of sources by discharges, and to the strong changes that have progressively suffered the natural ecosystems related to the capture, storage and natural regulation of water; which added to the high energy consumption and the high costs of its treatment, affects the coverage and provision of this service, especially in the most vulnerable population.
The extraction and processing of raw materials for the production of building materials and elements generates high deterioration of ecosystems and biodiversity in the areas of exploitation, generally with dynamics of deforestation, erosion and contamination of soil, water and air. Other processes, such as the production of cement, ceramics and metallurgy industries, involve high energy consumption of non-renewable fossil fuels, with a strong environmental impact.
According to the construction industry, this sector is responsible for almost half of greenhouse gas (GHG) emissions; added to the contributions in emissions from the cement, wood, metallurgical and ceramics industries. In this way, in their processes they consume 30% of the energy demand of the total industrial sector.
On the other hand, cement production is the sub-sector that generates the greatest amount of greenhouse gas emissions worldwide, given the high energy consumption required per unit of production. Energy consumption in the cement industry represents almost 2% of global primary energy consumption and approximately 5% of the energy consumed by global industry. It takes the equivalent of 60 to 130 kilograms of fuel and 110 kWh of electricity to produce one ton of cement. The cement industry generates, globally, 5% of global anthropogenic CO2, one of the main greenhouse gases contributing to climate change.
In this context, more than 90% of the energy used in cement production uses fossil fuels, mainly coal, coke, oil and natural gas. Thermal coal is the most widely used fuel in the global cement industry, given its higher calorific value and relatively low prices compared to oil. According to the World Coal Institute, globally 450 g of thermal coal are consumed for every 900 g of cement produced.
The metallurgical industry, producer of iron and steel, is responsible for approximately 5% of total GHG emissions, according to the International Energy Association – IAEA. For each ton of steel produced, 1.7 tons of CO2 are emitted into the atmosphere.
The excavation of mines, the removal of minerals and the processing of metals can cause serious damage to the environment and in extreme cases even destroy ecosystems. Environmental impacts, in many cases, are irreversible or very critical, such as the deterioration of land suitable for agriculture and the loss of the natural landscape. These impacts generate erosive processes and water pollution with soluble salts of potentially toxic elements (EPT), such as arsenic, selenium, lead, cadmium and sulfur oxides, among others. In addition, the excavated underground material can generate volumes of waste up to eight times higher than the original.
On the other hand, the wood industry generates significant impacts on the global forest cover, the current rate of deforestation worldwide exceeds fourteen million hectares (about 54000 square miles) per year, most of the losses occur in the tropics. The exploitation of wood is closely linked to deforestation and its collateral consequences of erosion, desertification and loss of biodiversity; and secondly to reforestation with fast-growing, short-cycle trees, which can drain soil nutrients and reduce site fertility and disrupt the soil in less time.
The global forest area in 2015 was estimated at approximately 4 billion hectares, with 36.4% in primary or uninterrupted forests. The forest cover occupies 30% of the total land area, however its distribution is mainly in countries of the tropics, being two thirds of the world area in only ten countries.
The global brick industry has increased its production since 1990. A sales volume of 26 billion euros was calculated for 2015, slightly more than 20% of the total sales volume of the ceramics sector. Since the 1990s a large number of factories have developed in Germany and Eastern Europe, countries that have the advantage of good raw materials. The brick industry in China has experienced an enormous boom and a high level of technology in production. Similarly, the production and technology of the ceramics industry is increasing in the Arab countries of North Africa, where manual processing has dominated until now.
This ceramic industry produces environmental impacts through the exploitation of clays, the intensified use of energy (especially coal), the emission of smoke, particles and gases and the disposal of waste, which contaminate the soil and water. However, this material presents advantages for the construction industry such as mass production, low cost, use of unskilled labor, thermal mass and structural resistance, which allow its role in low-rise construction.
The ceramic masonry combined with structural elements in concrete, allows the constructive development in height. In relation to the exploitation of stone materials (stone, gravel and sand) worldwide there are no precise indicators or statistics. This activity depends on the presence of geological reservoirs in each country and the economic viability, determined by various factors, including the type of mineral and its wealth, the depth of the reservoir and the technical process to be applied for extraction.
There are two types of environmental impact caused by extractive operations: the first is the overexploitation of non-renewable resources, which means their exploitation for future generations. The second is inadequate mining exploitation, which deteriorates the quality of the environment in aspects such as air pollution, soil, water, noise, destruction or disturbance of natural habitat, visual impact on the landscape and various repercussions on groundwater levels. Abandoned water deposits and pending rehabilitation quarries deteriorate the landscape and can pose serious environmental threats, especially as a result of acid drainage from mines.
It is expected that the production, manufacture and use of construction materials will continue to increase. According to the growing housing needs of the world population, this represents serious environmental impacts such as the deterioration of the landscape and biodiversity of the areas of exploitation, pollution of air, water and soil by the emission of gases and the dumping of solid and liquid waste.
The world population concentration in urban centers currently exceeds 50%; that means that more than half of humanity is located in urban areas. The availability of adequate urban land for residential development is limited by high land costs and the lack of suitable land, road infrastructure and services, generating precarious urban sectors with serious housing deficiencies and the generation of environmental impacts. Additionally, it is observed that the high costs for the development of formal housing construction processes for low-income sectors leads to a low quality of housing solutions, which in many cases does not meet the minimum conditions of space, structure, environment and comfort.
According to United Nations data, the world population in 2007 was estimated at 6,670 million people and is increasing at a rate of more than 75 million per year, so that by 2020 are estimated 8000 million and by 2050 a total of 9,200 million inhabitants. In this framework, the urban population was estimated at 3,290 million, 49% of the total population and the rural population at 3,380 million, just over half. For 2008, the world presented an unprecedented fact, more than half of the world population was concentrated in urban areas, so it is estimated that by 2025 the urban population will reach 57% of the total, with more than 4,580 million inhabitants; the projected rural population will be 3,430 million, representing 43%.
The United Nations Population Fund – UNFPA37 in its 2017 report indicates that most urban growth will occur in developing countries. Africa and Asia are expected to double the urban population between 2000 and 2030, while Latin America and the Caribbean will continue to increase the urban population more moderately. In this regard, the urban population of the developed world will increase relatively little, with projections ranging from 870 million to 1.01 billion people. The same document shows that 52% of the world’s urban population continues to live in areas with less than 500,000 people, areas with significant shortages of housing, transport, water and energy supply, waste disposal and other services, and few human, financial and technical resources at their disposal. In recent decades, small cities have always had more than half of the total urban population and are expected to account for more than half of the world’s urban growth between 2005 and 2025. The document goes on to state that the space occupied by urban settlements is growing faster than the urban population itself. The world’s urban population is projected to increase by 72 per cent between 2000 and 2030, while the area of built areas of 100,000 or more could increase by 175 per cent. According to recent estimates, based on satellite imagery, urban settlements cover only 2.8 per cent of the world’s land area, approximately 400,000 square kilometres, half of them in the developing world.
In this way, the demographic increase implies, in itself, a major negative impact on the environment, as a result of human activities in all sectors: industrial, energy, agriculture and waste production. Other critical factors are represented by the increase in the consumption of raw materials, especially those coming from natural resources for construction; energy consumption with an annual growth of 5%; the supply of drinking water, the shortage of which will increase every year, the generation and disposal of garbage and wastewater that are progressively affecting soils and water sources
This global panorama has led to a rethinking of the design and construction processes of buildings and particularly of the residential sector, so that the construction industry has been directing its efforts to the development of projects framed within the concept of sustainability, within an interactive dynamic of environmental, social and economic factors. Currently, there is consensus in world politics to adopt measures to mitigate environmental deterioration and overexploitation of natural resources, where the construction industry is not exempt. Housing projects should aim at the rational use of natural resources (water, energy, materials and soil), integrating non-conventional energy systems with innovative construction alternatives, including criteria for recycling and reuse of materials and, in general, actions to minimize negative environmental effects.
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