A Pinnacle of Energy Efficiency
Given the goal of creating a net-zero energy laboratory to house energy research, HDR Architecture designed a laboratory that will serve as an example for years to come.
The Georgia Institute of Technology Carbon-Neutral Energy Solutions (CNES) Laboratorybegan as a flexible, design-build, high-bay laboratory.
Located across railroad tracks on Georgia Tech’s North Avenue Research Area Science Park site, it was a shop-like laboratory; flexible enough for use, even without a defined user.
Taking advantage of the building’s program, site, and Georgia Tech’s enthusiasm for sustainability and energy efficiency, the team—Georgia Tech, Gilbane Building Co., and HDR Architecture—followed a rational design process focused on carbon neutrality. The project, which earned a High-Honors Award in R&D Magazine’s 2013 Laboratory of the Year competition, serves as a model. Research conducted in the laboratory explores carbon-neutral energy solutions in three types of flexible, energy-efficient laboratories.
Passive design first
Georgia Tech determined that to create a laboratory capable of meeting its net-zero energy use goal, all members of the design-build team should be engaged from the earliest stages of the project through construction and occupancy.
“We began with a healthy respect for the energy demands of modern laboratory environments, and a sense that this lab might somehow be different; that we could perhaps design a simple structure with only necessary systems,” says Daniel Rew, principal, AIA, HDR Architecture, Lawrenceville, N.J. “So we started with the idea of passive design first, which meant doing the simple things before we tried to integrate mechanical systems or generate energy with PVs or something else.”
In keeping with this straightforward approach, the design reinforced the “no-frills” concept by intentionally exposing the structure and leaving innovative technologies uncovered.
Throughout the project, energy modeling was used to evaluate energy-saving strategies and determine which systems should be incorporated into the design. “We started the project with an energy model, which established a baseline and gave us a breakdown of energy use," says Rew.
“The baseline model showed there was a lot of energy used in lighting, heating, cooling, and fan energy. So the first thing we did was look at the things that were using this energy. This is why we tried to maximize daylight,” continues Rew. “In heating and cooling we tried to minimize air-based systems and move toward a hydronic system with radiant slabs and fan coil units.”
The team developed four energy models through the process; and although intentionally not driven by the LEED checklist, the project achieved LEED-Platinum certification.
The CNES houses Georgia Tech’s Strategic Energy Institute, which is comprised of various research programs focused on sustainable energy solutions. Broken into three space types, the building is organized to accommodate evolving research programs with minimal need for modification, and to allow projects to move in and out unobstructed and without major reconfiguration.
“Breaking the program into three types allows for maximum flexibility, especially between high- and mid-bay laboratories,” says Rew. “It also gave us a way to evaluate each space type and challenge conventional design parameters for each of them independently.”
The high-bay laboratory is designed for a temperature range of 68 to 80 F. Anticipating the broader temperature range will not adversely affect the work conducted there. The flexible, project-based laboratory space, which runs the entire length of the north side of the building, accommodates industrial-scale fabrication experiments, and is fitted with a five-ton industrial bridge crane, allowing the movement and construction of large pieces of equipment and experiments. The high-bay laboratory has the capability of both forced and natural ventilation, and provides over three air changes per hour and a four-degree delta T. A radiant floor heating system maintains comfort up to ten feet above the floor within the high-bay and loading areas.
The mid-bay laboratory, located on the ground floor along the south side of the building, is designed for temperatures ranging from 70 to 76 F with the ability to provide individual laboratory spaces with more stringent temperature and humidity control. The mid-bay laboratory concept, developed specifically for this facility, is designed for smaller-scale experiments that require slab-on-grade space. Specialty laboratories, adjacent to the mid-bay structure include isolation chambers and wet and dry bench space, can be isolated and environmentally controlled for sensitive experiments and equipment.
The mid-bay laboratory contains one chilled-water VAV air-handling unit that is fitted with dual-energy recovery wheels. “The mid-bay AHU is intended to provide temperature-neutral air to the space; meeting only ventilation requirements,” says Rew. Cooling for individual rooms is accomplished with local cooling devices.
The computational laboratories and associated offices are also designed to maintain a 70 to 76 F temperature range to comfortably accommodate computational analyses, write-up, and other focused activities. Conference and meeting areas offer unobstructed views to the high-bay laboratory.
A focus on energy efficiency, sustainability
Materials chosen for the building envelope address energy-use reduction, maximize daylight and views, and generate renewable energy. The material palette consists of insulated metal panels, for a tighter exterior envelope; clear low-e glazing to maximize daylight and views through the building; translucent Kalwall to provide ample diffuse north light into the high-bay; and crystalline photovoltaic (PV) panels.
The original energy model showed lighting accounting for 14% of the baseline model, making an attractive and easy target to reduce energy use, according to Rew.
One goal of the project was to eliminate the need for artificial light during the day. Proper solar orientation—along the east-west axis—is a good starting point for effectively using daylight.
The high-bay laboratory is clad in glass and translucent panels on the north elevation, where the team wasn’t concerned about solar heat gain. Essentially a light-filled atrium, it requires artificial light only at night. The glass and translucent panel façade, along with clerestory windows, brings ample light into the north edge of the mid-bay, computational laboratories, and office spaces. The south elevation—associated with the mid-bay and computational laboratories—is clad with a combination of clear low-e glass and exterior shading devices to allow daylight to penetrate the building, while controlling solar heat gain. A fixed light-louver, made with convex-shaped blades, allows natural light further into the mid-bay space. On the office floor, a horizontal slot window with a shading above provides as much light as possible.
The design of the site expands the Institute’s campus-wide initiative to move towards a more natural ecology and increases water conservation, efficiency, and quality. Maximizing site permeability was important to reduce stormwater runoff and to “heal” the hard-pack condition of the site. The soil was rehabilitated using aeration cores to increase the rate of percolation. Permeable concrete is used in the parking areas. Bio-swales are used to convey water to a bioretention basin, which filters water before it enters the city storm water system.
Along the southern edge of the building, rain chains divert rainwater from the canopy above to an open drainage channel below. This water, along with water runoff from the roofs, is stored in a 20,000-gallon cistern for reuse.
Crystalline PV panels located on the roof, south elevation, and parking canopies generate 388,000 kWh per year of electricity; the equivalent to 56% of the building’s anticipated electrical demand.
The baseline energy model for the CNES project was established at 147 kBtu per square foot per year. Passive design, innovative engineering strategies, and on-site renewable energy brought the ‘as-designed’ energy model to about 29 kBtu per square foot: a savings of about 80%.