The winner of the first place in the Emilio Ambasz Prize for Green Architecture for International Buildings this year was European Investment Bank in Luxembourg. This truly iconic building was designed by Ingenhoven Architects.

This extensively glazed building is famed for its unique structural design, apart from several energy-efficient design elements. By virtue of these qualities, this office building achieved the coveted “Very Good” rating under the United Kingdom’s Building Research Establishment Environmental Assessment Method (BREEAM). It is also the first building on continental Europe to have been assessed under this scheme.

The headquarters of the EIB boast of a 170 meter-long tubular glass and steel structure with a zigzagging non-hierarchical office layout. This 72,500 sq meter building has enough office space and facilities for 750 employees and includes indoor ‘warm’ atria, a cafeteria, restaurant, and a connection to nearby buildings.

The building is completely shielded by 13,000 sq meters of glass that allow the penetration of daylight easily from all angles. Operable windows allow occupants to directly control the room temperature and permit natural ventilation.

Glass Roof

The highlighted tubular glass roof, framed with light-weight steel, covers 170m by 50m of building area.  Being glazed, the roof offers maximum daylight and transparency and is key to the building’s environment-friendly concept as it curves around the office floor plates. The tubular glass envelope allows for daylighting of the working bays. The transparency of the external envelope is reflected internally by an open office layout that promotes free interaction.

This glass roof curves around the floor plates to create atriums in the V-shaped “gaps” of the building wings. The landscaped winter gardens on the side of the valley are unheated and act as climate buffers; they reduce variations between the outside temperature and the desired temperature in the offices, thereby contributing to lowering heating requirements in winter and cooling requirements in summer.

 In contrast, the atriums on the boulevard side serve as circulation spaces. The largest atrium houses the main entrance to the building, and so temperatures in these areas have to be kept at a comfortable level. Both winter gardens and “warm” atriums are naturally ventilated through open flaps in the shell to draw fresh air into the building and to reduce heat gain especially in the summer months.

Cold water pipes also run through the concrete floor slabs, creating chilled ceilings in order to cool the building in summer and to regulate the building temperature between seasons. In winter, thermal energy from solar heat gain is used to heat the building, thus reducing energy consumption.

Energy Conservation

Mechanical systems such as lighting, sun shading, heating, cooling and ventilation can be controlled individually. Wastage is avoided as much as possible, as individual settings are reset to the most efficient levels possible several times a day by the central control unit. Staff members can open their windows to the atriums and winter gardens or to the outside at almost all times.

All offices are equipped with a control panel that allows building users to individually regulate blinds for sun shading, lighting and temperature. Artificial office lighting is restricted to 300 Lux throughout the offices. However, staff can illuminate their individual work spaces with desk lamps to 500 Lux. This overall reduction in general lighting Lux levels significantly reduces the building’s energy consumption.

All surfaces - walls, floors and ceilings - are also designed to make optimum use of daylight, enhance luminosity and thus contribute to a pleasant working atmosphere.
Efficient Construction Materials

Construction materials were selected in accordance with the energy used for their manufacture, with materials with the least energy consumption given preference. The internal façade frames, for example, which cover a surface area of 17,600m2, are made of wood rather than aluminium because research found that the energy used in the manufacture of the wooden materials is only 2% of that which would have been expended in the manufacture of the equivalent aluminium profiles.

This environmental philosophy extended to the construction site, where the majority of materials were chosen for their small environmental impact. For example, all wood used has been certified by the FSC or the PEFC (programme for the endorsement of forest certification).