Inspired by the waterfront qualities of its site, the environmentally- and culturallysensitive Kempinski Hotel Sail Tower explores the concept of an 145;architectural sail146;. Derived as an expression of the building functions and occupant activity rather than nautical utility, the sail elements create varying surface texture and effect. Integrated LED lights embedded in the sails emit a soft, low light that can be programmed to move gradually over the building, mimicking the wave of a sail in the ocean breeze. The sails, designed to be prefabricated off-site, are composed of aluminum frames wrapped with a durable, Teflon-coated synthetic fabric Gore-Tenara. Erected off-site and flat-packed, the units can be transported by elevator to each floor, expanded with an internal screw jack 145;mast146; mechanism, and set in place. The program for the 60-story, 63,000 sm building mixes a 242-key luxury hotel, 104 residential units, amenities, support spaces, and 600-car enclosed parking. The building massing is oriented to optimize water views, minimize solar exposure, and shade the entrance court. Privacy increases as the building rises, and circulation routes between the units and amenities, like the pool, were determined in collaboration with a local partner to ensure cultural appropriateness. The project, situated on a prominent parcel along the Corniche in Jeddah, marks the transition between the desert landscape and the Red Sea. The climate in Jeddah ranges from up to 115F in the summer to down to 55F in the winter, with high humidity year round. Analyzed using Ecotect software, the calibrated angles of the sails provide protection from sun and wind, direct views to the water, and increased privacy for each unit, turning as the building rises and the balcony depths increase.