The proposed building site was on top of the central urban park space in downtown Knoxville, Tennessee. This initially was received with negative connotations, however it quickly became the driving conceptual factor. The goal was to create a contextually sensitive design that provided more park space than the original site. The site is located adjacent to the Market Square Pedestrian mall, and one of the main drivers was to construct a 50,000 square foot building that also extended the pedestrian mall. The program is mixed use between public open market space, public park space and a private culinary school with private park space. This resulted in a formal expression that features a voided high-rise on the south end, a horizontal band of open markets, and a 20,000 square foot public park above the market. This large park space began to define the identity and drive many sustainable features for the culinary high-rise. Each level has subtracted voids that are filled with micro-parks. The park also manifested itself throughout the plaza, and on the eastern and western facades. The idea of landscape defining urban space is intriguing and powerful.
Measure 1: Design & Innovation
The entire design from the first concept sketch through the last detail was carefully centered on the idea of net zero energy and water, and a building that added cultural and civic value to the public. The building is designed to maximized passive strategies such as a solar chimney, winter garden, performative envelope, shading, harvesting, and ventilation. These systems shaped the form appearance, and internal conditions for the building. The challenge of working in the southeastern US comes with very high and low temperatures, and sun exposure. When the passive strategies are pushed past their inherent limits, integrated advanced building technologies pick up the slack. A liquid to liquid transfer geothermal system, automated building shading and ventilation, and solar panels were designed to perform at peak extreme conditions of the contextual environment. The culinary program was designed to work at very small floor plate sizes, and the market spaces share service space and are all accessed from the exterior. This allowed for nearly 100% space efficiency.
Measure 2: Regional / Community Design
The community and regional aspects of the design were important to the structuring of the program on the site and the formal expressions. Market Square in Knoxville, TN is an entirely pedestrian square. The square was doubled and extended through a series of urban hardscapes, tree gardens, water features, and sculpture gardens that reflected the public nature of not only the square but also the open market program. Above the market space is a 20,000 square foot intensive public park space. This entirely soft scape urban oasis serves as the central park environment for downtown Knoxville. By entirely placing the building in the center of the city and entirely removing a section of the automotive street the design serves as an advocate for alternative means of transportation. The site scored an 89 on walk score meaning that it is accessible to all needs of an urban inhabitant.
Measure 3: Land Use & Site Ecology
Integrating many levels and aspects of plants and park space through a horizontal, and vertical allowed for a diverse collection of ecologies. The main plaza is very rigid planting and design while the park level is very organic mimicking the natural landscape. The entire western façade, which faces a residential high-rise, is clad in a parametric designed skin made from natural bird and butterfly nesting. The facade is designed to act as a vertical ecosystem and provide alternative views to the neighbors and natural habitat. The site is a city block and is open for complete storm water retention and collection to provide water for the building and irrigation for the abundant plant life. Local food networks are accommodated due to the market program. This is designed to serve as an urban grocery store and allows for the culinary students to test and serve the community.
Measure 4: Bioclimatic Design
The horizontal market is 100% shaded from direct lighting except for the deep winter months. The high-rise is purposefully located on the southern end of the site to take advantage of the harsh lighting. The north, south, and eastern facades provide all of the cross ventilation, shading, and operable choices for inhabitants. The southern winter garden is designed to use convection to condition air and is controlled by a high performance building system. This system can become personalized due to the interior operable windows on the double facade. On can increase or decrease airflow and increase or decrease shading. All of the extreme climatic loads are designed to be handled by the geothermal radiant floor system. This means that inhabitants are comfortable year round without the use of fossil fuels. The massing allows for inset voids and subtractions that allow for increased shading.
Measure 5: Light & Air
Due to the shallow and concise floor sizes 100% of the occupants have access to views, natural lighting, and operable windows. This was a very important driving factor of floor layouts and formal expressions. Every floor of the design has either a large or a micro park for 100% connection to natural features. The intensive integration of precondition air devices, double facades, hollow floor plates, combined with the large solar chimney automated shading and ventilation allows for a 100% fresh air exchange rate at all times. This is the most sustainable and healthy aspect for occupants.
Measure 6: Water Cycle
The large city block plaza extension has a series of filtration bays that collect, filter, and move water to the exterior storage (aesthetic water feature). The entire building surface and park space has integrated collection and irrigation systems. The site not only handles 100% of the storm water but also can handle the surrounding urban fabric that is not designed to handle it. The exterior storage with natural filtration can hold 250,000 gallons of water, and this is filtered into the interior storage tanks that hold 35,000 gallons of UV filtered drinkable water. The site is 100% independent from city water sources for all building aspects, and site irrigation of extensive park space. The system is in continual use and cycles over and over.
Measure 7: Energy Flows & Energy Future
Through extensive energy modeling and calculation the building envelope and orientation alone reduces energy use by 59% over the current site code standards. This combined with the many previously mentioned passive systems and the geothermal system that is designed to manage 100% of building loads creates a building that is also independent of city grid energy. The day lighting and small floor plates eliminate the need for electrical lighting during the day, and solar panels provide the lighting at night. The floor cavities, geothermal radiant floors, pre-conditioned facades, shading, and solar chimney allow for the near elimination of forced air systems. The building is currently designed to not only eliminate energy use, but also create energy. Net Positive.
Measure 8: Materials & Construction
The material selection was confined to a regional palette. All sourced and spec’d materials were chosen and detailed in an effort to reduce the fossil fuels that are consumed during transportation. The building itself was designed as two separate structures. The horizontal element made from concrete is energy intensive up front, but is designed to last a long time. The high-rise was designed in modules. Almost all of the structural systems are to be constructed off site and assembled on site. This greatly reduces construction waste. All of the high-rise façade structures were designed as singular pieces that are repeated many times. Manufacturing energy, and construction time and waste were again greatly reduced. Modulated spans, proportions, and tiling greatly helped to conserve, approximate, and assemble interior cladding, and exterior cladding.
Measure 9: Long Life, Loose Fit
The program itself is mixed-use and is inherently flexible. All of the floor plates and plans are 100% open and can be reconfigured to accommodate many different programs over time. All interior walls in the high-rise are removable or reconfigurable. Potential alternative programs include office, retail, residential, commercial, and educational. The market spaces and simple in nature but can be divided many different ways with partitions or left as one singular element. The only aspects of the design that are 100% meant as permanent objects is the 20,000 square foot park, and large civic plaza extension. These are seen as public spaces and of value to the city and community. These assure the longevity of cultural urban space.
Measure 10: Collective Wisdom & Feedback Loops
I feel that buildings designed with primary passive strategies must be operated in an educated manner. Building occupants must be aided or pre educated in terms of how the building should operate to be as efficient as possible whether this is simply turning off lights, or using cross ventilation. I learned that to truly have a building that pushes the envelope of conceptual design and is at the cutting edge of sustainability there must be a predetermined mindset of integrated design. Sustainable goals should start up front and be used as aids to conceptual design or used as drivers of conceptual design. Working collaboratively with consultants must happen in the pre-design stages in order to correctly integrate a network of sustainable features that work together towards one outlined goal. Our goal for this project was first to create a lasting urban environment and second to stretch our understanding of passive and technological building systems as far as the design could take. The biggest lesson we learned was that there are many little effortless upfront design decisions that can greatly increase the efficiency of a design.