SUSTA INA BL E BENEFI TS OF ARCHITECTUR AL LY EXPOSED ST RUCT UR A L ST EEL (A E S S) As one of the basic precepts of sustainable design is to use less material, AESS feeds quite naturally into this goal. By choosing to expose the steel, there are significant savings in the reduction of additional finishes, reducing the embodied energy in the project. These can include the elimination of suspended ceilings as well as wall board or other more expensive finishes that might otherwise conceal the structure. The AESS aesthetic can also complement the use of more minimal and highly durable oor finishes. An AESS design that is looking to be sustainable will also need to focus on restraint in the use of material for detailing and choose member sections that result in a net savings in the weight of material. It will be important to be selective about finishes and fire-protection strategies when targeting an environmentally sustainable AESS solution. As addressed in Chapter 7 on Coatings, Finishes and Fire P rotection, the VOC level of the finish will need to be controlled, as a low-VOC paint is desired to reduce off-gassing. AESS will require a durable finish, particularly if located in high-traffic areas, so to prevent frequent repainting the durability of the paint or finish may have to be balanced with the issue of off-gassing. Some water-based materials may not provide the best level of service. If high VOC paints must be used then adequate time must elapse before occupancy starts. Intumescent coatings vary in terms of their VOC level as well, again whether they are water- or epoxy-based. There may be a need to examine the balance between the environmentally unfriendly nature of some intumescent coatings in light of the level of savings of finish materials and alternate methods of fire protection. Not all intumescent coatings allow for easy recycling or reuse of the steel, if looking for Cradle-to-Cradle or Design-for-Disassembly features. As the chemical make-up and performance of coatings is a quickly changing area, it is best to consult with the manufacturer regarding current specifications.
L OW- C A R BON DESIG N ST R ATEG IES Basic carbon emissions associated with buildings result from embodied and operating energy. Embodied energy is the result of the manufacture, transportation and erection/ construction processes. The broader definition will include carbon emissions from the use/program of the building, as well as transportation of the occupants as they commute to the building site or through business-related travel. Operating energy is responsible for approximately 80% of the carbon emissions associated with a building and as of the writing of this book, forms the primary target for impact reductions. Net Z ero Energy Design looks closely at significant reductions in the operating energy of buildings and asks that a building produce as much energy on site, via the use of renewable non-fossil fuel, as it consumes. Carbon Neutral Design looks to use no fossil fuel or carbon-emitting energy sources in the operation of a building. It also allows for community-generated renewable energy sources or offsetting to balance the equation.
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