Studies the thermofluid principles of, and design strategies for, natural and mechanical systems for conditioning high-performance buildings that are needed to reduce anthropogenic emissions of greenhouse gases in coming decades. Topics include the dynamics of airflow in buildings in urban areas and the design of natural and mixed-mode ventilation systems, low-energy strategies and systems for dehumidification and sensible cooling, and thermal storage at diurnal and seasonal time scales. System design in leading commercial practice is presented and critiqued by invited practitioners and students. Through a group project, students assess climate- and building-specific systems on the basis of energy consumption, carbon emissions, and resilience to climate change.