Just like roses, we humans, as a rule, prefer an atmosphere that is both light and cool. And here too, architectural applications featuring Solarflair pigments are already providing an answer. These include a permanent coating devised for a glazed dome roof. Here the problem was that the rooms beneath the dome would become unbearably hot in summer. Once again, the aim was to block light from the far-red end of the visible spectrum. Furthermore, because the human eye attains maximum sensitivity in light within the green area of the visible spectrum, the coating was also customised in such a way as to provide maximum transmission to light with a wavelength of around 520 nanometres. The results were exactly as predicted. “In the summer, says Rosenberger, “the coating reduces the temperature under the dome by as much as 13 degrees Celsius.”
   
She now plans to replicate this success with a new Solarflair-based specialist product for Venetian blinds by the name of Cool Blue. When applied to the surface of the plastic slats, Cool Blue deflects sunlight in such a way that the Venetian blind shines golden on the outside and shimmers blue on the inside. Unlike aluminium slats, however, the Cool Blue variety do not become hot in sunlight, for whereas the aluminium absorbs around 30 percent of the sun’s radiation in the form of heat, the coated slats simply deflect the radiation. “And for that reason, neither the slats of the blind nor the room behind it heat up,” says Rosenberger. “What’s more, the room is not only colder; it actually feels cooler.” Indeed, as Johann Wolfgang von Goethe noted almost 200 years ago in his Theory of Colours, “blue gives us a feeling of cold.”