Steel and Sustainability 1: Integration
As we challenge more rigorously the process of making buildings sustainable, steel proves itself a potent choice. In contrast to other green building materials, steel can contribute towards sustainable design from a variety of angles, and seemingly indefinitely. In this, the first of two articles that will illustrate green building strategies using steel, we will explore steel’s use from ore extraction; in particular due to its design integration and structural recovery.
Exploring notions of integration, we will frame steel within a holistic process for sustainable design and learn to recognize individual contexts and concomitant applications one building at a time. The emphasis here is on integration and the positive ripple effects when using steel. Early involvement of all stakeholders from the onset of the building process is the only way to achieve a high degree of integration. Integration, when well managed, produces favourable contexts of recovery.
The second article, “Contexts of Recovery,” will focus on the unique nature of steel and illustrate its seemingly infinite life as a building material. Indeed, steel can be recycled in its entirety, an infinite number of times, forever taking new forms and serving new purposes–without ever losing its workability and ability to perform. Recovery strategies include reuse and recycling. We will provide examples of steel recovery applications and review the experience of its implementation with architects, engineers and steel fabricators.
Once ore is extracted and steel is produced for the first time, its life never ends, providing effective sustainable strategies for green building projects. From the onset of conceptual development, steel contributes towards sustainability most efficiently when its design is integrated with other building systems and conditions. These will affect each other to achieve greater energy performance. As a building nears its first-time use, steel recovery strategies can result in the re-use of the steel structure in situ (which may include a structural design upgrade), or through dismantling (rebuilding the structure at another location), or even by re-using elements of the original structure for another building project. Steel recovery strategies can also result in recycling the steel elements of the structure (combined with other post-consumer steel products to produce other structural steel members).
At a time when architects and engineers are challenged to look a the environmental rating of each component of their buildings, and when most rating systems look at the performance of each component in isolation, designers need to reformulate both the questions and the evaluation methods so they can think holistically again. Good design includes notions of natural integration. These are evaluations of how each component may affect (or be affected by) the performance of another; and thinking and designing in ways that achieve more inter-related benefits, with the purpose of improving the overall green performance of a design. The most sustainable and best building performance can only be achieved through integrated design–a process suitable for steel.
The LEED Rating System looks at all the components of a building, allowing all inter-related benefits to be rewarded. For this reason, using steel is not only rewarded in the Materials & Resources category, but instead the rewards are indirectly cumulatively tabulated for other evaluative categories as well, such as Sustainable Sites, Energy and Atmosphere, and Innovation and Design Process (by illustrating the innovative notions of integration). Using steel can help other building components achieve their best LEED Rating in their respective categories (seemingly not associated with Materials & Resources), thus improving a project’s overall LEED Rating.
In applications where poor soils bring issues of compressibility and the necessity for overall building weight reduction, the use of a steel structure becomes desirable. Pile footings for instance, achieve the goal of Reduced Site Disturbance and by their nature Erosion & Sedimentation Control.
Energy and Atmosphere
The mechanical systems are reviewed and rated in this category. Structural steel can be designed to reduce the building section by accommodating longer spans with smaller member sections, thus reducing a building’s load requirements (HVAC) and the size of the required mechanical systems. This contributes to the Optimized Energy Performance criteria. The Utah Olympic Oval, for example, is an innovative cable suspension system supporting a very shallow steel truss roof. Steel is a lightweight structural solution that allows for these great spans.
Innovation & Design Process
This category may best recognize notions of integration in terms of a holistic approach to the overall project design. As an example, the Indoor Environmental Quality category rewards the use of low-emitting materials–but what about rewarding buildings that do not need these materials in the first place? Exposed structural steel eliminates the need for additional interior finishing products, which in turn saves the energy that would have been required to extract, produce, install and dispose of those products.
Also, principles of durability (not yet recognized or rewarded) can be presented in this category. Steel is clearly durable in its servicing state, but it is also entirely recoverable, which fulfills the long-term mandate of durability in a global sense. Using steel also maximizes the amount of materials that can be reused and recycled in the future, after the useful life of a building. Bolted connections would also enable easy future dismantling, making it more likely to reuse such members in another building as was the case for the Roy Stibbs Elementary School. It was built out of reused steel members from an old school dismantled in British Columbia and rebuilt 1000 km south, in Coquitlam.
This category also rewards designs that demonstrate an economy of materials. For example, the HSS structure members in the atrium of the Greater London Authority building designed by Foster and Partners serve dual functions by running hot water, creating a very large-scale radiator. And the Department of Education Building in Sacramento, California (awarded Gold LEED) illustrates the benefits of steel in designing lightweight structures: the structural and foundation systems are half the weight of an equivalent concrete structure.
When it comes to innovative atriums and natural light controls, steel and glass are important components of the integration process. The PNC Bank Operation in Pittsburgh (awarded Silver LEED) is one of the largest LEED-rated structures–where the quality of natural light within the five-storey atrium is monitored through the integration of automated sunscreens, and a high performance curtain wall and window system. At 87 Ontario Street in Montreal, difica Architect + Design created an atrium to join two buildings, thus providing natural light, additional indoor amenities, and a volume for stack effect integrated with principles of natural ventilation.
So, how green is steel? Its greatest potential is manifest through its integration with other building systems, and the resulting ripple effects on LEED categories not normally directly associated with steel. Long-span, lightweight solutions simply lessen the environmental burden on structures. Steel integrated to serve dual functions also shows great promise. For its recovery capabilities, both in terms of recycling and reuse, steel presents itself as extremely green.
Sylvain Boulanger is principal of Boldwing-Continuum Architects and a LEED-accredited professional practising in Surrey, B.C. Sylvie Boulanger is Executive Director for the Quebec Region of the Canadian Institute of Steel Construction, Montreal.