Westarkade Tower: First of a kind Energy Efficient Tower

The architects at Sauerbruch Hutton, Germany have built the world’s most energy efficient glass tower using “pressure ring facade”. The architecture incorporated the façade design developed in 1990s which managed excess sunlight in glass towers while building the 15 story glass tower in Frankfurt, Germany. The design includes a pressure ring facade, the first of its kind, reducing the effects of changes in the pressure around the building and enhancing natural ventilation. Complex and highly sophisticated computer controlled flaps in the outer facade open and close and equalize the pressure throughout.

The inner windows can be opened and strong winds entering the building are prevented. The building’s control system constantly gets a feedback from a rooftop weather station and from 40 sensors installed all around the building which measure pressure, temperature and sunlight. The system also has geothermal heat exchangers, heat capturing modules from basement data center and heat recovered from vented air.

All this reduces the tower’s primary energy demand to less than 100 Kwh of energy per square meter per year. It is approximately half of the current European average, and one third of the American.

The need for the mechanical ventilation will be almost eliminated in fall and spring as air from open windows will be available.  The unwanted summer heat is rejected by the Venetian blind installed horizontally. On the other side, pane of glass over the blinds and provided with ventilation at both top and bottom protects blinds from strong winds. This posed a major problem that when windows were opened, pressure difference created around the tower sent drafts across the floor which flew everything.
The firm overcame this challenge by collaborating with Stuttgart based firm Transsolar KlimaEngineering and came with an innovative design. This employed installation of 180 vertical ventilation flaps in the outer skin resulting in the management of airflows. This system is called as pressure ring façade by the designers.

The control system gives all occupants advice on when to open the windows displayed on LED panels installed in offices. But the occupants will have the final word on whether they wish to enjoy the evening breeze or not! The designers feel that the Westarkade tower is paving the way for future designs aimed to enhance natural ventilation and energy efficiency.