Towards a sustainable building stock in Sri Lanka
By Eng. (Prof.) Shiromi Karunaratne
Sustainable development has been defined in many ways, but the most frequently quoted definition from ‘Our Common Future", also known as the Brundtland Report is ‘the development that meets the needs of the present without compromising the ability of future generations to meet their own needs’. Is the Sri Lanka construction industry moving towards a sustainable future? This can be considered a topic worth rigorous investigation.
Construction plays a major role in Sri Lanka’s economy and is the fourth largest, contributing about 6% -7% of the Gross Domestic Product (GDP) of the country during the last decade. Traditionally, most construction materials are derived from non-renewable natural resources through mining and quarrying activities. With the increasing human population, there is an increased demand for natural resources to supply much-needed building materials. Today, second only to water, concrete is the most consumed material in the world. Compared to all the other building materials used combined in construction, this is as much as two times. According to world statistics, the total volume of cement production worldwide has amounted to 4.2 billion tons in 2019 compared to 1.39 in 1995, indicating a more than 200% increase over a period of fewer than 25 years. The world population growth over the same period (25 years) is only 36%. In 2019, the global production of industrial sand and gravel was an estimated 330 million metric tons. In 2016 alone, more than 7 billion tons of concrete have been utilized in Sri Lanka and the need for river sand per year has risen to more than 21 million cubic meters. Moreover, annually more than 4 million tons of concrete go as waste through construction and demolition activities. It is worthwhile to see how the production of concrete has affected global sustainability.
It has been estimated that the production of 1 ton of cement, contributes to 1.25 tons of Carbon Dioxide. Accordingly, to meet the global cement demand, approximately 5.2 million tons of Carbon Dioxide is released into the atmosphere annually. This is about 1.5% of the total Carbon Dioxide emitted globally in 2016. Further, it has been found that about 100-300 kg of Carbon Dioxide is released during the production of 1 cubic meter of concrete. The concentration of Carbon Dioxide in the atmosphere has risen from 370 ppm to 410 ppm during the last 20 years alone.
Furthermore, concrete production was responsible for about 9% of global industrial water withdrawals in 2012. This was approximately 1.7% of total global water withdrawal for direct and indirect human consumption predicted that by 2050, 75% of the water demand for concrete production could likely occur in regions that are expected to experience water stress.
According to the World Steel Association, construction is one of the most important steel-using industries, accounting for more than 50% of the world’s steel demand. Irrespective of the enormous resource utilization and associated environmental impacts, concrete, as well as steel, will likely remain in use as major construction materials well into the future leaving many more problems to be tackled. One of the other biggest environmental problems related to infrastructure development is energy use. The global building sector consumes around 36 percent of the world’s energy.
There is enough evidence to conclude that the construction industry is one of the most resource-intensive and high impactful sectors in any economy. The quota on global material resources, energy, and water uses as well as waste generation due to the construction industry is highly significant: it is responsible for 33.33% of material consumption, 11% of global energy-related CO2 emissions, and 54% of landfills due to lack of proper end of life cycle management methods. The building materials have an environmental impact at every life cycle stage: extraction of raw materials, processing, manufacturing, transportation, construction, demolition, and disposal at the end of the building’s useful life. Accordingly, the increasing global population is consuming more than their fair share of resources for meeting the present needs of shelter and related infrastructure while polluting the environment with various emissions. Therefore, the construction industry should be considered as one of the key stakeholders in achieving global sustainability.
Indicators of sustainability?
A sustainability indicator can be defined as a measurable aspect of environmental, economic, or social systems that is useful for monitoring changes in the relevant system characteristics. It is important to identify the midpoint and endpoint indicators that directly reflect sustainability aspects. Global warming, depletion of the ozone layer, depletion of resources, etc. can be identified as few important global mid-point indicators, whilst eutrophication, acid rain, ecotoxicity, etc. can be identified as few important local mid-point indicators. These indicators provide more holistic measures towards understanding the end-point impacts on human and ecosystem health and resource depletion. Minimizing the contribution towards these factors due to the construction can be considered as the focus of green building construction.
Can sustainability indicators be quantified?
On the path to sustainable development goals, more focus should be directed toward the contribution made as a nation or as a world towards sustainable indicators. It is important to describe them in a quantified manner and with the use of an appropriate index, we can understand where we stand, the path to be taken, and what we need to achieve. This will also lead us to a better understanding of the problem. As such, an index that involves all three environmental, economic, and social factors could be used to measure sustainability, however, this article emphasizes only the environmental indices. A traditional index may only indicate water pollution, air pollution, and generation of solid waste etc., however, a sustainability indicator will quantify activities that lead to pollution, emphasize the preservation of natural resources, and even focus on circular economic aspects, etc. The discussion of this article will be limited to the quantification of construction and resource utilization-related sustainability only.
Reduction of cost while achieving the desired quality and performance is usually given the highest priority in traditional construction approaches. However, it is high time that the local construction industry starts thinking beyond traditional means. As an island nation, Sri Lanka is indeed blessed with a variety of natural resources. However, most of these resources used in building construction are non-renewable, hence, need to be used responsibly. Depletion of natural resources should be minimized while maintaining a healthy building environment during all life cycle stages such as construction, operation as well as demolition of the building while reducing the water and energy usage.
Indications towards Sustainability
A building would have four distinct life cycle stages such as design, construction, operation, and demolition. The decisions such as material selection, methods of meeting HVAC requirements, etc., taken during the design stage would determine how the rest of the life cycle stages impact the environment (local as well as global), the health and well-being of the inhabitants, and the construction/operational costs. Among the life cycle stages of a building, the construction and usage stages contribute to most of the direct as well as indirect emissions, amounting to about 90 to 95% of the total. The wise use of building materials with lower emissions during construction and the use of passive design techniques for lighting and ventilation to reduce the energy use during the operation stages can considerably reduce the negative impacts due to environmental emissions. Proper quantification of these sustainability impacts would convince the parties involved to make correct decisions at the correct point of involvement.
Are methods available for quantification of building sustainability?
The main purpose of sustainability assessments is to gather and report information for decision-making during different life cycle phases of the construction, design, and use of a building. During the last few decades, the building sector has witnessed the development of two types of sustainability assessment tools. The first group of these tools includes those, which purely are based on a criteria system. The second group includes those tools that use the life-cycle assessment (LCA) methodology. The criteria-based tools have a system of assigning point values to several selected parameters. Among the criteria-based tools LEED (US), BREEAM (Great Britain), Green Mark (Singapore) and GreenSL (Sri Lanka) can be identified as the systems used in Sri Lanka widely. The LCA-based environmental assessment tools are used to make informed decisions, selecting design options of buildings as well as building materials during the design phase to reduce the environmental footprint of the construction during all life cycle stages. Though there are numerous tools to conduct environmental life cycle analyses, only a few can be effectively used for complete building-specific analyses. OneClick (Sweden), E-Tool (Australia), ATHENA (Canada) can be identified as tools having an LCA-based approach. Among them, OneClick and E-Tool can be identified as the latest web-based tools using recent updates of ISO-compatible international databases such as Ecoinvent, Gabi, etc. It is very important that these software tools represent the authentic construction methods/processes and accompany data representing the country where the study is being done. As of now, Sri Lanka does not have its own software tools nor a national LCA database for building materials to make such assessments viable. The only option is to use an available building LCA specific software tools with a database developed in another country. Though databases such as Ecoinvent and Gabi are among the few, most comprehensive databases in the world, it contains only a limited number of construction materials and processes related data to Sri Lanka. Hence, a national database containing local building material data as well as a building sustainability assessment software tool, which can identify the local construction methods and processes are of paramount importance for the future sustainability of the local building construction industry. Hence, more investment needs to be made in research and development in this regard.
With the financial support of the National Research Council (NRC) of Sri Lanka, the author has undertaken to develop a lifecycle approach-based building sustainability assessment tool. Unlike most of the tools available, even non-specialized users will be able to use this web-based tool easily to accomplish a full environmental life cycle sustainability assessment of a building project. This tool will incorporate local construction processes and materials so that the engineers and architects will be able to conduct environmental life cycle assessment of projects to make informed decisions on building form, material usage, operation and maintenance related decision making. Quantitative assessment of the sustainability of the Sri Lankan building stock and analyzing their effect on the environment, society, and economy should be a high priority in achieving 2030 sustainable goals for the country.
Eng. (Prof.) Shiromi Karunaratne
BSc.Eng (Moratuwa), M.Eng, PhD (Saitama, Japan)
Professor, Department Civil Engineering,
Sri Lanka Institute of Information Technology, Malabe
Chartered Member of IESL, Member of SLAAS – Section C