With all the technologies for green building today, the statement ‘A model of sustainable design’ has almost become cliché. Yet Clemson University’s Lee Hall expansion (Lee III) is actually designed to teach sustainable building design by example — literally — with an online real-time energy usage dashboard, truly making it a model for students and faculty in the College of Architecture, Arts and Humanities.
Completed in December 2011 and occupied in January 2012, the 55,000-square-foot, $16 million project was built to accommodate the expanding needs of the college, including 12 professional degree programs in the four departments of Art, Architecture, Construction Science and Management, and Planning and Landscape Architecture.
Built in alignment with the university’s commitment to reduce energy consumption 20 percent by 2020, Lee III is the 11th Clemson project to receive LEED® certification and its seventh LEED Gold building. The structure is zero-energy ready with future plans to incorporate photovoltaic (PV) solar panels to help the building absorb as much, or even more, energy than it consumes.
Currently, Lee III has an energy use intensity (EUI) of a mere 35kBtu/sf/yr and it exceeds the ASHRAE 90.1-2007 baseline by 52 percent. Building energy monitoring reveals the expansion is four times more efficient than the average building on the university’s 1,400-acre campus.
It also exceeds 70 percent energy-use reduction for university building types outlined in the American Institute of Architects (AIA) 2030 Challenge, which requires all new buildings, developments and major renovations be designed to meet a fossil fuel, GHG-emitting, energy consumption performance standard of 60 percent below the regional (or country) average/median for that building type.
In January 2013, Lee III was selected from more than 700 submissions to be one of only 11 buildings to receive the Institute Honor Award for Architecture from the AIA, the profession’s highest recognition of works that exemplify excellence in architecture, interior architecture and urban design.
With its numerous sustainable features, including custom skylights, automatic indoor lighting sensors, 100 percent glazing on north and south exposures (60 percent frit on east and west exposures), a vegetated roof, pervious paving materials, high-efficiency plumbing fixtures, a geothermal water-to-water heat pump system, in-slab hydronic radiant heating and cooling, integrated electrical and data distribution within the slab, and a mechanized natural ventilation system fully integrated with the building automation system (BAS), Lee III truly is a model of sustainable design.
An Impressive Design
The two-story-high building features exterior metal framing and sheathing while the interior has a main floor with a second-level mezzanine to house various faculty offices, meeting rooms and student classroom space. The east and west walls feature 12-inch concrete blocks with 4-inch (R-20) insulation for an assembly U-value of 0.0353 Btu/hr-ft2-F. A spray-applied vapor barrier in the exterior walls and 4 inches of rigid insulation in the masonry cavity also help minimize air leakage and thermal transmission.
To maximize day lighting, 24 generous skylights pepper the roof while north and south exposures feature entire walls of low-e glass that feature high-performance glazing with a summer U-value of 0.29 Btu/hr-ft2-F and a solar heat gain coefficient (SHGC) of 0.61. The east and west exposures also feature the same glass, with a 60 percent frit applied.
Operable and motorized windows automatically open when exterior conditions permit, allowing the mechanical systems to shut off completely. “We designed a building envelope that could take advantage of natural ventilation when temperature, humidity and pollen levels were ideal,” says Eric Richey, senior associate at Thomas Phifer and Associates. “The automated operable windows are programmed to open to bring fresh air into the building for ventilation, which also eliminates energy costs for heating and cooling during times of cross ventilation.”
With all the natural daylight, only the enclosed offices and areas underneath the mezzanine require overhead artificial lighting. And sensors control the T5 fluorescent light fixtures to automatically turn off when areas become unoccupied. Individual study areas also include small task lights to supplement natural daylight when necessary.
The plumbing system incorporates high-efficiency, 1/8-gallon-per-flush urinals, high-efficiency water closets and low-flow faucets with automatic sensors, reducing the water consumption by more than 35% compared to a typical university classroom building.
A vegetated roof reduces the heat island effect, in addition to treating storm water and doubling the building’s roof life. And to encourage the use of eco-friendly vehicles, the design even includes conduit for installation of electric car power stations with preferential parking.
Going Outside Their Comfort Zone to Find Energy-efficient Comfort
For the HVAC system, the design team looked to a number of alternative energy and energy-efficient systems to minimize energy loads. “Geothermal was on the table early on,” says Jim London, Associate Dean for Research and Graduate Studies at Clemson University. “A radiant heating and cooling system was also proposed, which would maximize the performance of the geothermal system.”
Trying an in-slab radiant floor heating system was a new concept for Clemson. And a radiant cooling system — in a high-humidity environment like South Carolina — was really radical. The radiant system would be flowing warm or cool water through crosslinked polyethylene (PEX) tubes embedded in the slab of the structure to heat and cool the building.
“Clemson was very hesitant,” says Brad B. Smith, AIA, NCARB and Managing Principal at McMillan Pazdan Smith. “We were plowing new ground. As a team, we were taking a big risk — that potentially could have a very big payoff.”
The engineers performed an energy study on the life cycle costs for a hydronic radiant system compared to a standard variable-air volume (VAV) system for the life of the building. The team compared installation costs, energy costs, maintenance costs and replacement costs.
The radiant system, with a projected payback of 10 years or less compared to a standard VAV system, proved very economical, especially given the high initial cost of additional PV panels (to achieve zero-energy use). And because a radiant system keeps heating or cooling near the floor where people are located, it made even more sense with the building’s high ceilings. The architects also found radiant appealing because it eliminated duct work from the ceiling, so they didn’t have to provide a hung ceiling which adds costs to the structure.
When the decision was made to go with the radiant system, the team knew it would be big — if successful — making it one of the few buildings in the Southeast with a natural ventilation system as well as a radiant cooling system.
Putting the Energy-efficient Concepts into Reality
When designing the radiant cooling portion of the system, engineers knew one of the most important factors was to ensure condensation did not form on the floor. To avoid this, the system needed to be controlled to keep the floor temperature about two degrees above the inside air dew point. The design team also incorporated a dedicated outside air system (DOAS) to economically provide dry air to the building. The DOAS saves energy by using the return and exhaust air stream to reheat the supply air after dehumidification through the cooling coil.
For the heating and cooling source, they incorporated a closed-loop, geothermal water-to-water heat pump system, which meant Lee III was neither connected to, nor reliant upon, the campus plant for heating and cooling. The geothermal system consisted of five nominal 20-ton heat pumps connected to 46 wells each 6 inches in diameter and approximately 400 feet deep.
Because a radiant system is designed to work in zones, which can switch from heating to cooling dependent on the indoor climate need, the heat pumps can provide simultaneous heating and cooling by taking advantage of heat transfer within the facility. For example, in certain months, the southern exposure has an abundance of heat from the afternoon sun while the shaded northern exposure requires radiant heating for occupancy comfort. The system can use the high return-water temperatures from the south zones to heat the north zones.
The geothermal wells are designed to offset approximately 100 tons of heating and cooling load, reducing Lee Hall’s annual energy consumption by 150 MWh. The geothermal system is also designed to cool the building directly (with no mechanical refrigeration) since the ground temperature hovers around 55 to 70 degrees Fahrenheit year round — the same temperature required for a radiant cooling system.
Controlling the HVAC system proved to be a unique balance between the hydronic radiant control system controls and the BAS. The engineer worked closely with the BAS contractor to properly integrate the radiant controls to ensure the system would operate at maximum efficiency.
However, the most unique portion of the new building is the energy-usage dashboard. Students, faculty and even visitors can go to http://buildingdashboard.com/clients/clemson/leehall/ via web browser or inside the building’s touchscreen kiosk to view real-time usage of the structure’s electricity, water, heating and cooling, and even compare usages between the new expansion and older sections of the building.
“Since occupying the building in December 2011, we’ve been tracking it against the energy modeling and it’s been right on course,” says Putnam. “It’s much more efficient than similar buildings on the campus.”
One year of energy monitoring has shown the DOAS saves about 5 to 10 percent of the energy costs, while the radiant system provides 50 percent energy savings compared to the baseline. In fact, the project was able to get all the energy points for LEED mainly due to the radiant heating and cooling system.
“The building is extremely efficient and is also very comfortable,” says Kate Schwennsen, FAIA, Professor and Chair for the School of Architecture at Clemson. “It does have a wider temperature range than some buildings, but our energy-guzzling culture has gotten accustomed to a very small temperature range for internal comfort. Getting thermally comfortable with a wider temperature range is something our society needs to do if we want to be more energy efficient.”
In fact, on one rather chilly evening, Clemson hosted a reception and dinner for the University Foundation Patrons. During the reception one of the distinguished attendees, who has been battling cancer for quite some time, remarked how it was the first time in months that her feet and legs felt comfortable. She couldn’t figure out why until she learned about the radiant system warming the floor, and in turn, warming her feet and legs, providing a thermal comfort that is ideal for the human body.
On a grand scale, the building has thoroughly realized — and even exceeded — the design teams’ and building owners’ expectations. From the towering windows to the mechanized ventilation to the automated lighting to the radiant and geothermal systems, Clemson University’s Lee III is a magnificent structure that not only effectively but impressively marries sustainability with form and function.
All involved in the project are very proud of the feat they accomplished by taking a big risk with new technologies for sustainable design. And from an architectural perspective, faculty, students and visitors can all appreciate the wonder and amazement that comes when sustainable design is truly beautiful.
“There is so much I appreciate about this building,” says Schwennsen. “I love its spatial and visual transparency that helps to create an engaged and engaging learning environment. I revel in how the changing nature of daylight transforms the structure —when combined with the reflection and transparency of the building and the views to and through, it is magical. But most of all, I appreciate how Lee III is supporting the creation of a more collaborative, public and innovative design education culture.”
Michael G. Talbot, P.E., LEED AP, is the founding partner of Talbot and Associates Consulting Engineers, Inc. His firm concentrates on the pursuit of innovative, environmentally benign engineering designs that adhere to high technical standards. He believes in a holistic approach to sustainability, utilizing the building elements as an integral part of the mechanical and electrical system design. Working with his clients to balance risks and rewards, he is able to evaluate and apply ground-breaking technologies alongside proven solutions to ensure facilities fulfill both their functional objectives and sustainable goals within budgetary constraints. His projects have received worldwide recognition, including an American Institute of Architects (AIA) Merit Award for Sustainable Design, the first AIA Carole Hoefner Cariker Sustainable Design Award and several technology awards from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).