Grand Challenges in Sustainable Design and Construction
The world has experienced unprecedented urban growth in the last and current centuries. In 1800, only 3% of the world’s population lived in urban areas. It increased to 14 and 47% in 1900 and 2000, respectively. Since 2008, for the first time in history, more than half of the world population lives in the urban areas (Laski and Schellekens, 2007). In year 2003, United Nations estimated that by year 2030, up to five billion people will be living in urban areas, accounting for 61% of the world’s population. The ongoing migration to urban areas has massive environmental consequences. This condition of unprecedented shift from the countryside to cities has been influencing climate change, where urban areas account for up to 70% of the world greenhouse gas emissions. Cities are growing toward megacities with higher density urban planning, narrower urban corridors, and more high-rise urban structures. Increasing urbanization causes the deterioration of the urban environment, as the size of housing plots decreases, thus increasing densities and crowding out greeneries (Santamouris et al., 2001). Cities tend to record higher temperatures than their non-urbanized surroundings, a phenomenon known as urban heat island (UHI) (Oke, 1982; Jusuf et al., 2007). Earlier studies show strong relation between urban morphology and increasing air temperature within city centers. Urban structures absorb solar heat during the day and release it during the night. Densely built area tends to trap heat, which is released from urban structures into the urban environment, increasing urban air temperature compared to surrounding rural areas and causes UHI effect. UHI affects street level thermal comfort, health, environment quality, and may increase the urban energy demand. As the number of buildings and associated infrastructures increases drastically in order to cope with the increasing population in cities, tremendous resources are required for the construction, operation, and maintenance of these buildings. Design of these buildings become very crucial as the resources required in the subsequent operation and maintenance is highly dependent on the quality of such design (Macmillan, 2005). Over the years, there has been tremendous effort put in to design “Green Buildings,” with the key objective to make the buildings more sustainable by minimizing the utilization of resources in the construction, operation, and maintenance of buildings. Building systems such as air conditioning and lighting are energy guzzlers, which can consume more than 60% of the energy consumption in a typical commercial building. They can also impact the indoor environmental quality. Thus, energy efficiency of the systems is crucial. Selection ofmaterials, which can minimize the embodied energy and construction waste is also important.