AEC Tech News: Focus on Productivity #1

Editor's note: Welcome to the first issue of AEC Tech News: Focus on Productivity. The fourth Thursday of each month, Cadalyst writer Kenneth Wong will present case studies offering a unique look at how organizations in the AEC community are using 3D CAD and related software to become more efficient and more profitable — and to produce better results day-to-day. Let us know what you think.

Let There Be Light!

Gerding Architects Makes the Most of Solar Energy
with 3D Building Model

In the early winter of 2005, as part of the Greenbuild Expo, a group of show attendees were ushered into the Sweetwater Creek State Park Visitor Center & Museum near Lithia Springs, Georgia. Here, in a tract of wilderness untouched by nearby Atlanta’s hustle and bustle, just a short walk from the ruins of an historic mill, visitors heard about the green-roof system, rainwater harvesting, solar-energy management and other environmental principles that have been incorporated into the architecture of the Visitor Center & Museum. Some of the visitors visibly squirmed during the presentation about the composting toilets. More than a few stomachs churned at all the talk about how the solid matter and liquid are separated and how the partially treated liquid (politely referred to as “compost tea”) is combined with the building’s graywater and routed through a drip-irrigation system eight inches below the surface to feed the landscaping with nutrients.

If you think hearing about them is difficult, imagine having to design a building that can accommodate and sustain these operations over time. That’s the job of Dan Gerding, the principal of Gerding Architects, a firm the Georgia Department of Natural Resources hired to design the building.

What It Takes to LEED
“The biggest challenge was the design process,” says Dan Gerding. “We were doing a LEED building with fairly aggressive goals in sustainability.” Initially Gerding and his client set their sights on a Silver LEED certification, but they soon realized they could aim higher, for the more prestigious Gold Certification, even possibly reaching Platinum level.

To get to that level,” Gerding points out, “we have to have a tightly integrated design process. It requires a lot of cross-disciplinary discussions between ourselves and other design disciplines: civil engineers, landscape architects, mechanical engineers and electrical engineers. We can’t just come up with a concept and then toss it over to them and say, ‘Go ahead and design this.’” That’s because the building’s sustainability components -- solar-gain control, water conversation, waste-stream management and so on -- must interlock to produce the desired effect.

Gerding explains why 3D design software is essential for this project: “You do invest a fair amount of time to model in 3D, so if we have a simple building -- say, a restroom and shower facility for a park, and the budget’s pretty small -- and the design doesn’t require a lot of exploration, we might just draw the plan in 2D [in CAD software] without ever assigning heights or properties to the walls, because we’re probably never going to look at it in 3D. But if you have a project like [the Visitor Center and Museum], you have a fairly complex building form, so you want to explore the design fully.”

In the past, Gerding Architects has used MiniCAD/Vectorworks from Nemetschek. The firm also owns two or three seats of AutoCAD to facilitate communication with consulting engineers who use that software. For the past ten years, including the Sweetwater project, Gerding’s primary CAD software platform has been ArchiCAD from Graphisoft. Gerding realizes there might be other 3D products on the market that are comparable to ArchiCAD, but he was attracted to ArchiCAD’s use of the BIM (building information model) approach. The Visitor Center and Museum was designed entirely in ArchiCAD. Gerding has recently added SketchUp from @Last Software to his 3D repertoire for creating early conceptual designs.

Here Comes the Sun
One of the objectives of the project was solar efficiency, or, more precisely, figuring out a way to admit maximum light while avoiding direct rays. “We use [ArchiCAD’s Sun Studies feature] to analyze the building orientation and the placement of window shading,” says Gerding. “We put the building facing south, so it minimizes direct exposure to eastern and western sun. We added exterior sunshades and interior light shelves to further control the light. As we were experimenting, we were also making changes to the 3D model. So we made changes, then we would simulate the environment under new solar criteria: We picked the latitude, picked the seasonal sun, then followed the sun track in each of those scenarios to see how much sun was coming into the building. Through these exercises, we were able to figure out the shading required to achieve about 95% blockage of summer solar gain.”

ArchiCAD’s Sun Studies tool enables Gerding Architects to determine the right orientation of the building to achieve the desired level of summer solar-gain blockage. This series of renderings depicts (clockwise, from top left) early morning, midday, late afternoon and nighttime effects.

Green Fever
“We got a lot of mileage out of the ArchiCAD model,” reflects Gerding. “There are two areas with vegetated roofs, both integrated into the hillside. It’s the kind of thing that you won’t be able to visualize in elevation drawings -- they don’t really describe it. So we used the 3D model to make a 2-minute fly-though animation with music. We used it to sell the concept to the client; the client in turn used it to publicize the project.”

The Sweetwater Creek State Park Visitor Center & Museum integrates with its natural surroundings. The vegetated rooftop area blends into the hillside without a visual break.

The Visitor Center and Museum was designed to support solar panels, but installation was deferred because of resource limitations. When the stakeholders saw the progress of the building, however, green fever swept through the donor community. The project received two additional pledges, ranging from $10,000 to $30,000. The additional funds, along with a used photovoltaic solar panel array donated by British Petroleum, resulted in about 20% of the building’s electrical needs being supplied by solar power. Overall, the building will use approximately 51% less regulated energy than what is allowed by the Georgia state energy code.

A New Aesthetic
In his interview with Doug Llewelyn of The Business News Magazine 24/7, Dan Gerding says, “The computer has allowed architects to do, in general, buildings that are so complex that they wouldn’t have been able to figure out all the calculations in the old days. More and more, we’re going to see that it’s creating a new aesthetic.”For more information on Sweetwater Creek National Park, go to www.gastateparks.org/info/sweetwater.

About This Issue
AEC Tech News: Focus on Productivity, mailed the fourth Thursday of each month, presents case studies offering a unique look at how organizations in the AEC community are using 3D CAD and related software to become more efficient and more profitable — and to produce better results day-to-day.