Hidden wavelengths in white light can change how warm a room feels
White light that looks identical to the human eye can still contain different mixes of red and blue wavelengths that change how warm or cool a room feels. In a Penn State experiment, blue-enriched white light allowed participants to tolerate air temperatures about 1.3 degrees Fahrenheit warmer. If larger studies confirm the effect, lighting could eventually work with heating and cooling systems to widen comfort ranges and reduce building energy use. A room can look exactly the same and still feel different. Penn State researchers found that hidden differences in white light can shift how people experience indoor temperature. The study tested whether ordinary-looking white light could affect thermal comfort. The work was led by scientists at Penn State and focused on red and blue wavelengths inside white light. Those wavelength differences were invisible to participants. Yet they changed the gap between perceived and real temperature by as much as 1.3 degrees Fahrenheit. Julian Wang, professor of architectural engineering at Penn State and principal investigator of the study, said the goal was to see whether …
