Guest lecture By Professor William W. Nazaroff

The talk was the first of a series of presentation entitled “Civil Engineering Distinguished Talks” (in short “CED-Talks”).

Along business-as-usual trajectories, atmospheric CO₂ levels will rise from the current 400 ppm to the range 650-900 ppm by year 2100.  The best alternative for limiting climate change during this century involves transforming society’s energy supply and end-use systems to achieve large-scale cuts in fossil carbon emissions.  Both adaptation and mitigation responses are needed. The large scales of necessary changes pose enormous challenges for those concerned with the built environment.  If we do successfully navigate past anthropogenic climate change caused by an overreliance on fossil fuels, what changes might we anticipate for the late 21^st century in the built environment?  One important feature would be a weaning away from distributed combustion as a major energy transformation process.  Electricity will be provided to buildings from sources with low net carbon emissions. We will need to curtail the burning of fuels for purposes such as heating and cooking. Personal control over key attributes of the indoor environment will become common, promising associated benefits such as lower overall energy use and higher occupant satisfaction.  In low-income countries, household air pollution problems will diminish as a consequence of two pivotal transformations: (1) replacing inefficient kerosene lanterns with highly efficacious LEDs; and (2) replacing inefficient and highly polluting solid fuel cookstoves with efficient and clean electric induction appliances.  Within this large frame, my research group currently focuses on a few key aspects of indoor environmental quality that center on human occupants.  We are studying the gaseous, particulate, and bioaerosol emissions from human occupants of buildings.  In Singapore’s tropical climate, we are studying the extent to which occupant satisfaction and cognitive performance can be met at higher temperatures augmented by user-controlled fans.  Like Ulysees in the Odyssey, society faces perils on our sojourn through the energy-climate nexus in the 21^st century.  On one side is the inertia of the status quo, which makes the unacceptable business-as-usual paths the more probable ones to be followed.  Hazards also lie along our path if we myopically focus on saving energy in buildings without sufficient attention to the importance of meeting the real needs of occupants.  However, if we study carefully, execute well, and choose wisely, we may find calmer waters beyond Scylla and Charybdis.