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The Efficiency Opportunities in Mixed Use Design

Part Three: Iconic Design and Mixed Usability

In the first post of this series, I addressed the universal interest in iconic design. Generally, a structure?s shape is designed before the systems and system components are determined. Therefore, it can become a challenge to design systems that optimize sustainability while maintaining the iconic frame of the building. Engineering often becomes a method of justifying the iconic design.

Opportunity: Creating a Mixed-Use Facility
Not only do vertical, mixed-use facilities conserve land resources, they also present opportunities for efficiency through the load shifts that take place between day and night operational spaces. Many of these mixed-use facilities combine space types with varying operating hours, such as combinations of corporate, retail, and residential. This mix keeps the space occupied and operational 24 hours a day. For example, corporate spaces require operation during daylight hours while residential spaces require larger utility loads in the evenings. This constant yet shifting occupancy encourages the building owners to shift the utility loads as well, allowing for an overlay of infrastructure.

Greening Study for Willis Tower

An example of these load shifts can be found in the Greening Study of the Willis Tower. This study examined the energy savings available from a modernization of the tower ? including improvements to the building envelope, windows, lighting, HVAC, and water systems ? and the opportunity to shift these savings to power an adjacent, newly constructed 50-story hotel through a shared primary plant. Since energy use peaks during the day for corporate Willis Tower tenants and peaks in the evening for hotels, this infrastructure overlay would produce a more constant use of the systems throughout the day and allow the hotel to draw net zero energy from the power grid.

View the entire panel discussion at the CTBUH Shanghai Congress from which I have highlighted over the past three months.

Project Gallery: Willis Tower Greening and Modernization