Paul de Ruiter Architects has an impressive portfolio when it comes to sustainable buildings. And with each building, the sustainable options increase again. "Luckily," says the architect. “We want to tempt more and more people to sustainability.” Architect Paul de Ruiter (58) has been working on the theme of sustainability for a quarter of a century. In the 1990s, he was already way ahead of the troops. Fortunately, the subject is now seriously on the map. "Thanks to new technologies and materials, a lot is now possible. That is exciting and innovative and buildings really benefit from that." Smart facade An example that De Ruiter mentions is the QO Intercontinental hotel in Amsterdam. "This is the most sustainable hotel in Europe, near Amstel station. The facade of this hotel is climate-active. I call it The Chameleon Skin. This was once the subject of my PhD research." In short, it means that the facade can respond to the arrival of the hotel guest. De Ruiter: "As soon as a hotel guest leaves the room, all shutters are closed, the heating systems are switched off and the room remains at the right temperature. When the guest returns, everything turns on automatically. Thanks to this smart facade, the hotel saves 65 percent on the heat supply and 90 percent on cooling."