New research led by University of Hawai‘i (UH) at Mānoa atmospheric scientists found that the century-old yardstick used across many industries to estimate air-conditioning and refrigeration energy demand — called cooling degree days — is missing something fundamental.
New research led by University of Hawai‘i (UH) at Mānoa atmospheric scientists found that the century-old yardstick used across many industries to estimate air-conditioning and refrigeration energy demand — called cooling degree days — is missing something fundamental. Their study, published recently in Nature Communications, reports a new, physics-based version of the metric — effective cooling degree days — that captures how temperature and humidity together impact the actual work a cooling system is required to do. Applying it across North America, they found that cooling efficiency has been quietly declining by 2–4% per decade since 1971, and that the old temperature-only metric misjudges how much cooling is required in different regions, overstating demand in some places and understating it in others.
“Estimates of cooling degree days are used everywhere,” said Jake Casselman, Atmospheric Sciences postdoctoral researcher in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “Utility companies, grid operators, energy planners, and engineers use them to anticipate electricity demand, and financial markets trade futures on them to hedge against unusually hot summers. If that yardstick is biased in ways that depend on a region’s climate, then the planning decisions built on it are biased too. That can mean building the wrong amount of power generation in the wrong place, or misjudging where the grid is most at risk during a heat wave.”
Read More at: University of Hawaii at Manoa
The research team assessed efficiency and energy demand of cooling across North America, including in the desert Southwest. (Photo Credit: National Park Service)
