Total energy breakdown of a typical hot-rolled steel retail building (approximate area less than 600m²/6,460sqft) after 50 years. The beams and columns account for less than 1% of the energy and Global Warming Potential of the structure. This will vary as a function of the building use, but the study shows that the choice of structural material is of less significance than other factors (operating energy as well as durability of enclosures, windows and doors). The calculations were created using Athena Life Cycle Software. Source: Life Cycle Assessment of a Single Storey Retail Building in Canada by Kevin Van Ooteghem
The Lillis Business School at the University of Oregon in Eugene, OR, USA by SRG Partnership, LEED TM Silver, uses exposed steel as a means to reduce finishes. The white finish of the steel is also useful in increasing levels of reflectivity in the space to assist daylighting.
Windows & Doors 1,52% Foundations 0,80%
Total Operational Energy 93,07%
Beams and Columns 0,62%
Tot. Embodied Energy 6,93%
Enclosure (Walls & Roof) 3,99%
REDUCE MATERIAL Even between steel systems it is possible to achieve material reduction. The ability in the production of structural steel shapes to create sections that take advantage of distancing the material from the neutral axis, as in the case of W and HSS sections and OWSJ systems, allows for a streamlined use of the material that is not possible in structural members or systems that must use solid cross sections. This lightness of structure translates into less general use/weight of the material as well as reduced costs in transportation and foundation construction. HSS sections can additionally reduce the amount of coating material required, comparing the surface area of a W vs. a hollow section of equal carrying capacity (assuming that no interior finishing of the HSS member is required). This holds true for most painted finishes. Galvanized steel, however, must be coated on all surfaces, including the interior of hollow sections, to ensure corrosion protection, increasing material use. The galvanizing process is more energy-intensive, adding environmental cost. REDUCE FINISHES AESS buildings allow for the reduction of finish materials. Because the AESS as such is the architectural expression and requires no further covering or cladding finishes, the reduction in the use of other materials saves resources, the labor to install coverings and associated energy. Fireresistant intumescent coating systems allow for exposed steel expression in a multitude of building types and uses. When assessing the impact of the structure on indoor air quality, architects must select steel finishes that have low or no VOC emissions. This will be significant in choosing an intumescent fire protection, as the water-based coatings are presently applicable only to interior surface protection and tend to dry more slowly than the more volatile epoxy-based systems. REDUCE LABOR The industrialized nature of the shop fabrication and construction process of steel structural systems can reduce site work and can simplify erection procedures, which translates to reduced labor and travel-associated CO2 costs. If looking more holistically at steel fabrication, it will be easier in the future to source the energy supply for fabrication facilities from renewable energy sources than it will be to supply renewable energy to a construction site. Even if the end use of the project will include significant renewable energy such as photovoltaics and wind, these are not likely to be in place until closer to the completion of the project.
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