Molybdenum and its applications

Sustainable Bioclimatic Second-Skin Façades Save Energy & Transform Buildings

Bioclimatic architecture is an important new international design trend that can help to reduce building energy requirements. It refers to designing buildings and spaces (interior and exterior) using local climatic conditions to improve thermal and visual comfort. These designs provide protection from summer sun, reduce winter heat loss, and make use of the environment (e.g. sun, air, wind, vegetation, water, soil, and sky) for building heating, cooling, and lighting. Stainless steel is being used for innovative, award-winning, bioclimatic projects around the world because of its longevity and low maintenance requirements.

Examples are provided below but for more information read the feature articles:

CTBUH Journal
The Use of Stainless Steel in Second-Skin Façades, December 2013, Issue III

The Construction Specifier
10 Key Questions about Exterior Shading, October 2014, pg. 38
Designing Sunshades into the Façade – Stainless Steel Selections, June 2012

Construction Canada
Complementing the Building Inside and Out with Metal Fabrics, October 2014
Designing with Stainless Steel: Bioclimatic hybrid façades, October 2011

EuroInox Case Studies
Metalworking workshop in Gradignan
Solar shading systems: Düsseldorf Airport

Second-Skin Façade Technology

In bioclimatic design, two façade layers, an insulated wall and a second shading or sheltering layer, are used so that the inner wall is shielded from weather. The windows in the inner wall are operable and sometimes computer controlled to maximize natural ventilation. A variety of technologies are being used for the outer façade including louvers, woven mesh, perforated screens and green (plant) screens. They may actively change with varying conditions or remain passively fixed.

The outer façade can transform the appearance of lower cost new buildings or revitalize outdated existing facades at a much more reasonable cost than a more elaborate curtain wall. This makes them a cost effective aesthetic choice for renovation or new construction.

Active Second-Skin Façade Systems

There are many variations on active second-skin façades. Hybrid systems employ an operable shading system over the insulated glass façade, which maybe between inner and outer glass layers or be the outermost wall. The two layers can be from 0.2 to 2 m (0.7 to 6.6 ft) apart, and incorporate integrated sunshades and natural ventilation.

All have computer-controlled mechanical operating systems that work with the building’s heating and cooling systems, making it possible for them to respond dynamically to varying conditions. By adjusting to match the sun’s trajectory, they maximize the benefits of solar radiation while minimizing heat gain. Energy is necessary to operate these assemblies, and maintenance of the mechanical and sensing systems is required so they are not suitable for all applications.

ThyssenKrupp AG Headquarters

ThyssenKrupp AG worked with TKQ architect consortium JSWD Architekten and Chaix & Morel to design a new seven building corporate campus in Essen, Germany. The German Sustainable Building Council (DGNB) has awarded the project a Pre-certificate in Gold based on the new German Certification for Sustainable Buildings. Energy requirements are expected to be 20 to 30% below statutory requirements.

All of the buildings are simple glazed structures but their appearance is unique because of their second façade. The buildings are wrapped in automated sunshade systems with Type 316 stainless steel horizontal and vertical slats or custom perforated sunscreens. These active motorized sunshade systems have moveable triangular, square and trapezoidal fins are automatically adjusted with changing conditions to save energy. Used in combination with natural ventilation, the system eliminated the need for air conditioning.

ThyssenKrupp AG headquarters
Photos: Courtesy of ThyssenKrupp AG

Council House No. 2

The City of Melbourne Australia’s multi-award winning, ten-story Council House No. 2 achieved the Green Building Council of Australia’s highest Green Star 6 rating. Relative to typical construction, it uses 85% less electricity, 87% less gas, and 72% less potable water, and reduced CO2 emissions by about 60%. Half the energy consumption for typical Melbourne buildings is for traditional air conditioning, which was eliminated by using active and passive sunscreens, natural ventilation and conductive cooling of the ceilings.

Council House 2
Photo: Ronstan Tensile Architecture

The west facing public façade has a façade of timber slat sunscreens supported by a lightweight Type 316 stainless steel tension cable system that can be pivoted vertically in response to the time of day and angle of the sun. On the north side of the building, passive green plant screens were used on the sides of balconies to screen low angle sun and filter glare. They are supported by a Type 316 mesh and tension cable system. The vegetated screen extends over the roof and provides an arbor like sunshade for the rooftop terrace.

Transformative Passive Systems

Unlike tensile supported systems that parallel the insulated wall, lightweight framing supports for woven mesh or perforated panels allow the distance between the inner insulated skin and exterior hybrid second skin to vary making seamless curving, geometric and other shapes possible. This can dramatically change the appearance of a new or existing building at a much lower cost than installing an undulating insulated curtain wall. Passive screens avoid the maintenance requirements of automated systems and are suitable for any environment.

Guangzhou Children’s Activity Center

Guangzhou, China’s 2nd Children’s Activity Center provides teaching, performance and exhibition space for after-school and weekend arts-education courses for primary- and secondary-school students. Designed by Steffian Bradley Architects (SBA) and completed in 2006, this 42,735 m2 (460,000 ft2) concrete and glass building has a capacity for 20,000. The dramatic and seamless compound curves on the exterior were created by a Type 316 stainless steel mesh metal panel system.

The design eliminated the need for air-conditioning in common spaces which substantially reduced energy requirements. The woven mesh maximizes natural light inside the building, while creating a distinctive identity and enhancing energy savings and sustainability.

Guangzhou, China’s second Children’s Activity Center
Photo: Steffian Bradley Architects

Stockholm Congress Centre

The new Stockholm Waterfront, a Swedish congress center located centrally on the city’s harbor, is a layered structure designed for significant energy reduction. A second façade of contoured, ribbon-like, softly reflective stainless steel angles outward from the glass wall making the building distinctive. Long service life, low maintenance materials were desired for this screen, which employed 3500 Z-shaped duplex 2205 stainless steel sections with a semi-reflective matte finish, 3 to 16 m (9.8 to 52.5 ft) in length.

Stockholm is not a severe coastal environment, but sections of the screen are sheltered from rain and regular maintenance cleaning is not expected. The stainless steel producer suggested the more corrosion resistant and higher strength duplex stainless steel 2205. Completed in early 2011, it received Swedish green building certification.

Stockholm Congress Centre
Photos: Outokumpu