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Solar modeling the UMaryland Ellipse

July 16, 2013
HDR Rendering of the pedestrian plaza below the ellipse.  Window panels are colored red and white in keeping with the University of Maryland's colors.

HDR Rendering of the pedestrian plaza below the ellipse. Window panels are colored red and white in keeping with the University of Maryland’s colors.

The newly constructed Physical Sciences Complex on the campus of the University of Maryland in College Park, includes a beautiful elliptical oculus  passing upward through a three-story office bridge over a pedestrian plaza space. Created as an iconic architectural landmark, the opening is designed to have much the same visual impact in the space below as the Pantheon’s in Rome. Inside the building, open pedestrian spaces surround the curtain walled oculus, adding an additional dimension to the experience of the space.

Activation of the west face of ellipse by the high pre-noon soon.

Yellow dots show the area exposed to direct solar gain, orange shows reflected gain, and red shows the hot zone resulting from many reflections concentrated in one location. The orange dots on the western face of the ellipse show the contributing curtain wall panels.

Unfortunately, the installed glass curtain wall system is also highly reflective and creates a solar convergence to rival those at the Vdara Hotel and Disney Concert Hall.  The elliptical form of the opening does not create as precise a focus as does the curve arc at the Vdara, but it is nonetheless highly effective at concentrating light rays into one area,  resulting in a hot spot intense enough to melt polystyrene panels being installed into the space.

Highest heat loads are generated in the late afternoon as the western sun reflects off the east face of the ellipse.

Highest heat loads are generated in the late afternoon as the western sun reflects off the east face of the ellipse.

HDR architects asked me to assess the intensity and location of the hot spot, which I accomplished using a combination of Heliotrope and additional Slate Shingle modeling and solar routines. I found that the hot spot below the ellipse is active throughout a 6-hour mid-day period for 3 months before and 3 months after the summer solstice. Furthermore, the changing curvature of the ellipse moves the hot spot as the sun moves, creating a pattern of focus that changes throughout the day.

These images illustrate the patterns of light movement that create the hot spot in the plaza. Fortunately they are mostly confined to an earth berm intended, not for human inhabitants, but for plantings. The heat levels are too high for even the hardiest of cacti, however, leading to some tough redesign decisions. Possibilities include testing to see whether window film treatments are sufficient to mitigate the problem, or designing and installing shades to either mitigate or eliminate the convergence entirely.

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3 Comments leave one →
  1. July 16, 2013 10:59 am

    I hate to sound like the old guy yelling at the kids on his lawn, but . . .

    *HOW* does this not occur to people during the design phase?!?!? That bright thing in the sky isn’t anything new. Its motions have been well-understood by designers for . . . well, for millennia. The actions of a curved reflective surface in relation to it are also well-established. And, as if that weren’t enough, didn’t the Disney Inadvertent Tanning Facility drive the point home?

    The mind boggles. On the other hand, their blind spot has generated work for you, so hooray on *that* front!

  2. July 16, 2013 2:49 pm

    A fair question. Of course it is always easier to point fingers afterwards. But there are a couple of reasons these issues have started showing up over the past few years. One is that the high efficiency glass makes the problem much bigger. A second is that clients are looking for sexy forms. We like to point to the one-ups-man-ship in Dubai and say how silly it is that every building has to be bigger and curvier and “bling-ier” than the last. But the fact is that that aesthetic is also influencing both clients and architects all over the world.
    The problem is that we’ve let go of our traditional solar thinking and handed it off to consultants with heavy computer tools that are not agile enough to be included in the early design flow. That’s when the form making happens and when my work can come into play. I create fleet-footed tools over time and customize them to the design problems in the moment. Its a combination of those historic techniques inside the computer environment and at the pace of today’s design process. Then when you have your forms dialed in and are ready to spend time on a few alternatives, then you can turn on the big guns to analyse exact heat loads and light levels and verify results in an engineering sense.
    It would indeed be far cheaper to hire me up front instead of retrofitting a building facade to fix problems afterwards. There was a presentation this past week at RTC NA by Kelly Cone of the Beck Group in Dallas (they were local architects for Renzo Piano’s Nasher Sculpture Center there) describing the shading proposals they were suggesting to Museum Tower across the street. 4-6 million dollars to eliminate the solar reflections onto the museum. And as Kelly pointed out, that still didn’t address the problems that were being created for every other building in a six block radius. It doesn’t make for happy neighbors and, as we’ve seen, it doesn’t sell condos.

    • July 16, 2013 3:27 pm

      I get the desire for bling in Starchitecture, and I understand the increase in reflectivity is going to change the issues.

      But both in my undergrad work at Cal and graduate work for Charlie Brown’s classes in Portland (with you) this stuff was a regular topic of discussion. I understand the Nasher more, given the deliberate nature of excluding light from the structure. It’s not so much the form as it is the very nature of the exercise: Diverting solar gain by definition means sending it elsewhere. But with the others it smacks of, if not negligence, laziness and/or shallowness of process.

      It seems like a symptom of a larger phenomenon, especially when adding the ice-fall problems of Gehry’s Stata Center. Simply because we *can* design without site foremost in our minds, should we? And how divorced from site can design become before it is simply sculptural fetish, devoid of both context and humanity?

      And, as an aside, how much of this is a repeat of the sometimes failed Modernist experiments with then-new cladding materials?

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