Tec-Sun polycarbonate incorporates differential light technology. When light is brighter outside the conservatory, a highly reflective surface is created which, rejects 80% of the suns solar energy whilst allowing high levels of natural light in. Looking from the outside in the appearance is solid. However, looking out from the inside, the roof is transparent. This is achieved by incorporating finely divided metals into the polyester laminate. At night the roof takes on a "solid" appearance which can be enhanced by up lighting to create a warmer more room like feel.