Sensitive urban revitalization often goes hand in hand with sustainability. When an underpopulated neighborhood blossoms, its city becomes denser and more resource-efficient. Hamburg, Germany, provides a timely example, with its ambitious plan to turn the industrial HafenCity area into a cultural, business, and residential hub. The slate of projects under construction there includes the undulating Marco Polo Tower by Stefan Behnisch, RIBA, Martin Haas, and David Cook, RIBA, of Stuttgart, Germany-based Behnisch Architekten.

Scheduled for completion in 2009, the 16-story tower is projected to house 59 luxury apartments, as well as a ground-floor restaurant. On the same 2.2-acre plot will sit the headquarters for Unilever Germany, which the firm is also designing.

Marco Polo Tower's biomorphic form affords views of the city and the adjoining Elbe River. Its curved balconies will double as shading devices and provide shelter from winter winds. The architects also hope to include energy-conserving triple-glazed window walls. And a planned rooftop solar cooling system, in which solar-heated water drives an absorption cooling machine, will lower the building's ecological impact while ensuring chilled indoor air in hot weather.

project: Marco Polo Tower, Hamburg, Germany

key green strategies: Triple glazing, solar cooling, passive cooling, and mixed-use

architect: Behnisch Architekten, Stuttgart, Germany

developer: HOCHTIEF Projektentwicklung, Hamburg

structural engineer: Weber Poll, Hamburg

project size: 431 square feet to 2,476 square feet per unit

site size: 2.2 acres (includes Unilever Germany office building site)

construction cost: To be determined (TBD)

sales price: TBD

units in project: 59

renderings: Courtesy Behnisch Architekten