Studies on Virtual Water Content of Urban Buildings in India

Background/Objectives: Water conservation in buildings seldom considers the water used in building production or in other words the virtual water content of buildings. There is very few reported research in this field, especially in the Indian context, despite the fact that water scarcity is a burning issue requiring urgent attention. The paper attempts to provide a baseline study of  virtual water content of urban buildings in India and establish its significance in sustainable design practice. Methods: Virtual water content is calculated through case studies of one residential building each from Kolkata and Pune under a common framework. The methodology includes the computation of inherent and induced virtual water, where the former is on account of the materials and the latter is for the actual construction. The inherent water considers five major materials of construction viz. bricks, cement, steel, aluminium and glass, as data pertaining to embodied water coefficients of only these are available on date. The inherent and induced virtual water when added gives the total virtual water content expressed per unit floor area. Findings: The virtual water content was calculated at 19.3588 kl/m² and 16.2707 kl/m² for Kolkata and Pune respectively. The inherent water component at 61.45% and 82.00% of the virtual water for Kolkata and Pune respectively conformed to earlier findings that the inherent water was comparatively more significant than the induced water component. An important finding of the study was that buildings in warm-humid climate used more water in their on-site processes as compared to their counterparts in moderate climate. The quantum of virtual water translates to water requirement of 1233 families for one whole year on an average. This is a significant amount of water hidden in buildings that goes unnoticed. Applications/Improvements: Rapid urbanization and growing water scarcity necessitates serious attention to virtual water content of buildings for a more holistic approach towards water conservation leading to a sustainable future. In this context, the study assumes a novel approach in our understanding of virtual water content of buildings and hopes to inspire further research in this area.