How do we design a sustainable built environment for ten billion people? What technologies and policies will move us in this direction? These are questions that will challenge engineers, who will create the built environment of the twenty-first century. An engineering education in the 21st century must prepare students to address these challenges.

Engineering educators often describe their curricula with the metaphor of a toolbox. Engineering principles of mass conservation, energy conservation, and thermodynamics, to name just a few, can be viewed as powerful tools for solving problems and designing processes and products. But how do we use these engineering tools in designing sustainable systems? This presentation will show how basic engineering principles, especially the concepts of mass and energy balances, can be used in characterizing the sustainability of engineered systems. Mass and energy balances will be applied at multiple scales to illustrate how even basic engineering concepts can give us powerful insights concerning the design of engineered systems. The presentation will conclude with an overview of how engineering educators, throughout North America, are incorporating concepts of sustainability into curricula.