The researchers studied a special type of sunlight concentrator called dielectric crossed compound parabolic concentrator (dCCPC) for controlling daylight in buildings. They found that dCCPC can help save energy and improve indoor lighting by adjusting its transparency based on the sun and sky conditions. By using mathematical models, they were able to accurately predict how well dCCPC would work in different situations. This research shows that dCCPC has great potential for improving daylighting in buildings.