Case Study: City of Communications, Madrid

The City of Communications business park project in Madrid, Spain was born at the concept design stage back in 2002. Global Architectural association, HOK International was responsible for the master plan and urban design of the building. Once this stage was complete, local architect Rafael de La-Hoz Castanys took over for the architectural delivery of this project.

At the time of completion in 2008, the building had the largest horizontal surface for collecting solar energy in Europe. The complete structure has over 16,600 PV solar panels that run the length of the entire office complex on the building rooftops.

At over a km in length, the rooftop has an area of 390,000m2, of which 26,000m2 is occupied by solar PV panels. The installed power reaches an approximate 4MW peak, generating over 3.6GWh of power per year. This design enables the building to save 15% on climate conditioning in winter, and 34% in summer, as well as saving on lighting. The façade of the office blocks is a double skin, where the external glass is hung out from staggered glass fins. The project involved an investment of approximately €21.8 million.

Although this building has both a glass façade and a canopy, neither of these things holds the PV power. Fundamentally, the entire roof of this building is photovoltaic, constituting one of the largest horizontal surfaces for collecting solar energy in Europe. The solar panels that cover 26,000m2 of the roof of the canopy transform solar thermal energy into electricity, at the rate of 4,389,000kW/h/year. This represents a reduction of 2000 tons of CO2 emitted into the atmosphere. The roof 's shadow, cast over the façades, cloisters and entrances, unifies, protects and refreshes.