Embodied impacts of buildings from energy-carbon-water nexus perspective: A case study of university buildings

Abstract

Despite extensive investment in energy efficiency efforts, the energy footprint of the building sector still contains over 40 % of the world's annual consumption of energy. Although most of a building's life cycle energy use comes from operational activities, a portion of it stems from embodied energy (EE), which is directly expended in a building's construction and indirectly consumed using materials. Because each material consumes not only different amounts but also different types of energy sources, studying embodied carbon (EC) is equally important. The building construction sector also consumes nearly 1/5th of global fresh water, which is becoming a grave concern, given the increasing frequency of droughts and wildfires. The fact that material manufacturing and construction processes also consume water makes it essential to not just assess energy and carbon but also embodied water (EW). The literature recommends evaluating total EW including direct and indirect EW as well as any EW associated with EE use. In this paper, macroeconomic models are utilized to compute and analyze the energy, carbon emission, and water embodied in four university buildings. The results show that the total EE, EC, and EW values for the four case study buildings vary from 13.1 to 51.1 GJ/m2, 1.4–10.0 kgCO2/m2, and 2,820–12,900 gal./m2, respectively. The EE values also show a near perfect positive correlation with EW values. However, the share of EREW in the total EW ranges from 13 % to 16 %, indicating that a decrease in EE use may not help decrease a majority of EW.