Researchers have discovered that current global energy forecasts significantly underestimate the effects of climate change on urban heating and cooling systems, projecting a shortfall of about 50% by the year 2099 if greenhouse gas emissions continue at high levels. This gap could have substantial consequences for essential sustainable energy planning moving forward.
Most existing research primarily focuses on chemical feedback mechanisms—large-scale processes that involve intricate relationships between energy consumption, greenhouse gas emissions, and the atmosphere. However, a research team from the University of Illinois Urbana-Champaign is concentrating on the frequently neglected physical interactions between urban environments and the atmosphere, which can impact local microclimates and eventually influence global climate.
In a recent study led by civil and environmental engineering professor Lei Zhao, the researchers highlight that waste heat generated at the municipal level from heating and cooling buildings can significantly affect local climates and energy needs. The results of this study are documented in the journal Nature Climate Change.
“The heat produced from heating and cooling systems constitutes a major portion of the overall heat generated in urban areas,” Zhao explained. “These systems emit considerable heat into the atmosphere, causing cities to warm up, which in turn increases the demand for indoor cooling systems, further amplifying local heat.”
This phenomenon is part of what the researchers refer to as a positive physical feedback loop involving the use of cooling systems and the rising temperatures in urban settings. The authors mention that the increasing temperatures due to climate change may potentially reduce energy consumption during winter, creating a negative feedback loop that should be factored into any forecasts concerning temperature and energy demand.
The study indicates that a decrease in heating usage would result in less heat being released into urban areas, leading to milder urban warming compared to current climate conditions.
“This creates a negative physical feedback loop that might lessen the decrease in heating demand,” Zhao noted. “However, it does not negate the effect of the positive feedback loop. Instead, our model implies that it could create more pronounced variations in seasonal electricity demand, which requires thoughtful planning.”
To incorporate these often-overlooked physical factors into the broader understanding of climate change, the research team employed a hybrid modeling framework that integrates dynamic Earth system modeling and machine learning. This approach examines the energy demand for urban heating and cooling amidst the uncertainties and variability posed by urban climate change, taking into account the differences in cities related to income, infrastructure, population density, technology, and temperature tolerance.
“The key takeaway from this study is that energy projections should consider both positive and negative physical feedback loops,” Zhao stated, “as this will assist in comprehensive climate impact evaluations, inform evidence-based policy decisions, and enhance coordination around energy planning sensitive to climate changes.”
Zhao’s team is actively exploring how factors such as humidity, building materials, and future climate mitigation strategies will further influence their models, aiming to refine energy-demand projections.
Zhao is also connected with the Institute for Sustainability, Energy, and Environment, the National Center for Supercomputing Applications, and the Gies College of Business at Illinois.
This study was supported by the National Science Foundation and iSEE at the University of Illinois Urbana-Champaign.
