⋅ Frechette described a “reduce, absorb, generate” approach his team used for the design of Chicago’s Clean Technology Tower: 1. Reduce energy use as much as possible. 2. Absorb using the orientation (natural ventilation, sunlight) to drive the design. 3. Generate renewable energy on site.
Clean Tech Tower is a net-zero energy, mixed use development for Chicago based on the concept of biomimicry and featuring wind turbines at the building's corners.
⋅ Since new construction makes up less than 1 percent of the building stock in Chicago, the city (as all cities should) will focus on reducing the footprint of existing buildings.
⋅ One specific example is Adrian Smith + Gordon Gills Architecture's retrofit of the Willis Tower (formerly the Sears Tower), which includes the construction of a high-performance hotel alongside the existing building that will have a “symbiotic relationship” with the tower (alternate peak energy times, reusing water, etc). The team hopes to apply the lessons learned from this relationship on an urban scale.
The retrofit plan of Willis Tower includes a 50-story hotel along the south side
of the plaza to operate using the energy savings from the Willis greening project.
⋅ They chose a “study area” of Chicago: The Loop, the city's central core encompasses about 550 buildings (90% built before 1975) with some 85 million square feet. The area accounts for 1 percent of the city's total area but ten percent of its carbon emissions. Frechette and Forest investigated ways to rejuvenate the area and increase the density with mixed-use facilities while reducing carbon emissions/energy useper person.
⋅ Quoting Dr. W Edwards Dening, “You can’t manage what you can’t measure,” Frechette noted the lack of tools to quantify the costs, payback, and intangible benefits of retrofitting individual buildings, and the resulting impact on the city.
⋅ The team sent people onto the streets to collect data and feed it into a “BIM for cities” program. They then created a computer model to simulate the area and calculate its carbon footprint. Each building becomes a “data mode” to compare and contrast—use, size, total carbon, era, energy use, etc., and the parametric model shows the city under different “lights” (land use, carbon emissions, electric utility filters).
⋅ With the model, you can change a building’s program (from commercial to mixed use, for example) or facade, and see the carbon impact on the city with an estimated accuracy of plus or minus 5 percent according to Forest.
The audience seemed excited about the model’s potential, though the speakers were not able to give a timeframe for availability of the Chicago data or the program itself. Frechette and Forest are currently working with the city to seek funding for pilot projects, or “energy districts.” Stressing the importance of building owners’ cooperation in recovering the data, Forest admitted that it took a certain amount of “arm twisting” from Mayor Richard M. Daley, a known green fanatic, for building owners to release the information, with some holding out entirely. With the surprise announcement thatMayor Daley will not seek re-election, the firm might be more successful with the door-to-to door method—after all, Forest is a former professional football player.
See the full video presentation of The Decarbonization of Chicago plan by Robert Forest, AIA, and Roger E. Frechette.
