Georgia Tech Builds Carbon-Neutral Lab to Study Carbon Neutrality
By building a research laboratory to develop technologies to reduce the earth's carbon footprint, the Georgia Institute of Technology hopes both to help solve a nagging environmental issue and to provide a construction industry model for the production of "no-frills" net-zero energy-use buildings.
The $22.4-million Carbon Neutral Energy Solutions Laboratory in Atlanta, targeting completion this fall, will develop technologies aimed at reducing global warming, such as carbon sequestration. From the start, though, the university faced an ironic twist. On a square-foot basis, labs can use up to 10 times more energy than a standard office building, according to the project's architect-mechanical engineer, HDR Architecture. The new lab had the potential to be a carbon hog.
In late 2008, the local offices of HDR and Gilbane Building Co. joined forces to compete for the project's design-build contract. The team tackled the inherent contradiction by proposing a carbon-neutral research lab that would itself be carbon neutral, at least in the sense that it would be an energy miser that produced as much electricity as it used, and designed to use less than half the energy of a typical lab.
The pitch was too good for Georgia Tech to resist. By designing a high-energy-use facility to a low-energy-use standard, the project and the building itself would be an experiment in sustainability and a case study in the steps needed to reach net-zero energy use (NZEU).
Setting an Example
The lab project is expected to achieve LEED-Platinum status, the highest certification from the U.S. Green Building Council's Leadership in Energy and Environmental Design green-building rating system. "We want [the project] to be the most sustainable building on campus," says Howard Wertheimer, Georgia Tech's director of capital planning and space management. "We want to continue to raise the bar on sustainable design and construction," he says, and "we need to be good stewards of our resources."
The school also wanted to set an example for other builders—to make them "feel like they could go for the same thing," says Princeton Porter, HDR's designer.
For the lab itself, the mission is to use proven technologies, and not to present a showcase of extreme possibilities. An important design directive is a "no-frills" approach to building systems. They needed to be cost effective and easily duplicable, says the team.
HDR and Gilbane faced a tight schedule. To help meet it, HDR created a building information model for architecture, structure and mechanical-electrical-plumbing systems that enables systems coordination. It was the first time HDR had included architecture and MEP systems in a single BIM platform.
HDR shared a coordinated BIM with Gilbane. It was "light years ahead" of most, says Paul Stewart, Gilbane's senior project manager. That sped Gilbane's clash detection and model review process, he says.
The design-build team worked in concert to determine the lab's green features. HDR would provide options to Gilbane, which then assisted with analysis for first cost, life-cycle cost and sustainability impact.
The rectilinear building is compartmentalized by function. One half of the box is a 8,300-sq-ft single-story space with a 40-ft-high ceiling. The other half contains two levels: a 5,000-sq-ft research facility topped by a 8,800-sq-ft office section.
HDR looked to 19th-century industrial buildings—with more natural ventilation systems—to provide occupant comfort. The facility's high-ceilinged space, intended as a "dirty" lab for large-scale energy research, is the building's most "retro" section, mechanically. Completely naturally ventilated, the "high-bay's" north wall has operable louvers for 3 ft and operable windows at the top. A pair of 24-ft-dia industrial ceiling fans will run in the summer and cool the building by an estimated 8˚F maximum.
"The draft effect induced by the vertical distance between the high windows and the low louvers generates significant air flow," says Andrew Konop, HDR's engineer for heating, ventilating and air conditioning.
In the winter, fans will run at minimum flow to de-stratify the air. For emergency ventilation, Georgia Tech had HDR add 10 propeller exhaust fans. A radiant under-floor heating system is the main heat source.
The two-level section features a dual-energy recovery wheel—which exchanges energy from the exhaust and supply airstreams—that will supply "neutral" air to the lower research space, called the "mid-bay." The wheel saves energy because it avoids reheating air—often required in other laboratory air-handling systems.
Fan-coil units will provide more cooling on a localized basis, as needed. The units feature high-efficiency motors that enable their use at lower speeds, further lowering the building's energy use.
In the office space above, HDR utilized an under-floor air-delivery system for cooling.
Using the Light
The building is set along an east-west axis. A glass curtain wall provides most of the building's daylight. Skylights bring light into the center of the building.
In 70% to 80% of the building, the lighting system will have fully dimmable, programmable ballasts that will enable light to be localized. "They can section the lighting off however they want," says Tommy Lane, HDR's electrical engineer.
The most significant "light-related" item on the building is the 296-kW solar photovoltaic (PV) array that will feed electricity to the facility. Extra power will be fed back to the campus.
Before a cost analysis was done, the team assumed it would use thin-film photovoltaic cell technology. But a competing technology known as crystalline won out because the cost for thin film had skyrocketed and the cost of crystalline had dropped, says HDR's Porter. Also, crystalline's efficiency has increased significantly.
Overall, there are 1,200 PV panels. In addition to rooftop arrays on the main building and nearby parking structures, HDR and Gilbane integrated 33 kW of crystalline PV into a canopy on the lab's south face.
For vertical applications on building exteriors, crystalline PV panels are less friendly to install than thin film because they can't be applied directly to a substrate and must be installed within a frame, says HDR. That meant special detailing.
The PV added about $2 million to the project's cost. But that was fine with Georgia Tech, which received $11.6 million in stimulus funding. Gilbane also bought the PV array from an Atlanta area manufacturer, fulfilling a "Buy American" clause of the stimulus funds.
"Some people who are fond of spreadsheets might look at [the return on investment for solar] as 20 or 25 years," says Georgia Tech's Wertheimer. With so many future builders on campus, the educational influence is immeasurable, he says. "The ROI is Day 1. That's just part of our educational mission."
Editor's Note: This file replaces an earlier file to clarify and correct project details.
| ENERGY EFFICIENCY OPPORTUNITIES | POTENTIAL ENERGY SAVINGS (%)* | METRIC TONS CO2 SAVED |
|---|---|---|
| Daylighting | 14 | 58 |
| Premium efficiency lighting | 15 | 65 |
| LED site lighting | 1 | 3 |
| Premium performing envelope | 19 | 41 |
| Natural ventilation high bay | 5 | 21 |
| Energy recovery | TBD | TBD |
| Solar thermal desiccant regeneration | TBD | TBD |
| Trombe wall | 4 | 13 |
*preliminary estimates, based on ASHRAE averages tbd: to be determined |
