-200% 26% Progress in reading among students due to daylighting Sources: (absenteeism) independent studies from Lockheed Martin in California and ING Bank in the Netherlands; (turnover) study from Story County (Iowa) Human Services; (eyestrain, headaches and drowsiness) Department of Design and Environmental Analysis, Cornell University, “Worker Reactions to Electrochromic and Low-E Glass Office Windows;” (in schools)Heschong Mahone Group, “Daylighting in Schools: An Investigation into the Relationship Between Daylighting and Human Performance.” How can glass and glazing cut down HVAC and lighting costs? HVAC systems account for about 40 percent of total energy use in commercial buildings, according to the Department of Energy. Meanwhile, lighting systems capture about 16 percent of electricity costs. Building owners can offset costs in both areas through the use of high-performance glass and glazing products, and by maximizing natural daylighting.