Design space exploration of a high-performance building façade

In mechanical engineering, product quality and innovation are paramount objectives. In architectural engineering, the comparable goal is to deliver high-performance buildings. Pattern r+d is an Atlanta-based building analytics consulting firm delivering daylight, cost and energy modeling services. CEO Sandeep Ahuja describes how the firm was involved in a living-building challenge competition for a new building at Georgia Tech. “I always like to give the short answer before I get into details,” she says, “so how do I design a high-performance façade? Parametrically.”

In this project, Pattern r+d worked to develop new methodologies to test for building façade performance. The methodology began with a simple question from the design team: What façade options fulfill the performance criteria along with the design objective?

With most projects, Ahuja notes, “it is common to test five, ten or even 20 façade options for various performance metrics, but I knew that in this particular case a manual methodology of testing one option versus another for each metric was going to take far too long for it to have any effect on the actual design of the building. I needed accurate results to help inform design decisions.”

“Being a strong advocate of the famous MacLeamy’s curve [see note and figure at end of article] and integrated teams,” she continues, “Pattern r+d was working closely with the design team, mechanical engineers, landscape designers and cost estimators to help provide all the required information to develop this façade analysis.” With inputs from all, the façade shading options shown below were tested:

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Source: Pattern r+d. (Click image to enlarge.)

The team settled on these key performance metrics: EUI [energy use intensity] (with a breakdown of heating and cooling), daylight, thermal comfort (percent people satisfied) and glare. “Once we got all the results, with all the metrics, Pattern r+d created a custom interactive tool to be used by the design team,” Ahuja says. A live version of this interactive tool is available here.

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Source: Pattern r+d. (Click image to enlarge.)

“For instance, if we are studying the south façade, and want to design the façade for the lowest glare and highest daylight, we would be left with only two options,” she says, as shown below:

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Source: Pattern r+d. (Click image to enlarge.)

“And if we further add it to have the lowest energy and highest thermal comfort, we are only left with one option,” shown below:

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Source: Pattern r+d. (Click image to enlarge.)

“This tool was able to provide quick and easy-to-understand performance guidance specific to the building,” Ahuja concludes. The project continued in similar fashion to add automated shading, electrochromic glass and manual interior blinds to the mix of options to test for glare reduction for visual comfort.

The MacLeamy Curve is named for its originator, Patrick MacLeamy, chairman and CEO of the global design, architecture, engineering and urban planning firm HOK. It illustrates the benefits of moving from traditional building delivery methods to the methodology known as Integrated Project Delivery (IPD). As the AIA summarizes it, “Integrated Project Delivery (IPD) leverages early contributions of knowledge and expertise through the utilization of new technologies, allowing all team members to better realize their highest potentials while expanding the value they provide throughout the project lifecycle.”

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The MacLeamy Curve. Source: Daniel Davis (www.danieldavis.com)

See also Optimizing capex/opex tradeoffs in built-asset engineering.