Stone in Architecture / Commercial

Hokie Stone contributes to LEED certification

In keeping with campus tradition, local “Hokie Stone” was incorporated into the design of a Virginia Tech’s new chiller plant — not only helping to conceal the mammoth size of the structure, but also adding points for LEED Silver certification

September 3, 2013
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Virginia Polytechnic Institute and State University — popularly known as Virginia Tech — not only is dedicated to providing quality higher education, but it also takes great pride in its architecture. While the earliest campus buildings were constructed of brick, it soon became clear to university leaders during the late 19th and early 20th centuries that stone architecture would create a more prestigious image. As a result, the first building using regional limestone — affectionately called “Hokie Stone” — was erected in 1899, and since that time, many buildings throughout the campus has been designed with the material. In 2010, the entire board at Virginia Tech passed a resolution that Hokie Stone should be used on all buildings constructed on the University’s central campus. Most recently, a new chiller plant was completed, and the use of the regional limestone contributes to the Leadership in Energy and Environmental Design (LEED) Silver certification that is being sought for the building’s design.

BLT Architects (BLTa) of Philadelphia was the design consultant for the new chiller plant, which is located within the Life Sciences District HABB Quad development, as outlined in the university’s 2006 campus master plan. The expansion of the academic campus will include future construction of academic buildings, a structured parking deck and ancillary buildings. The plant is a new component to the university’s central chilled water system, and will serve future on-campus facilities.

According to BLTa Senior Associate Sherman C. Aronson, AIA, LEED AP, 85% of the materials coming off the site are being recycled and 50% of the project’s material costs went for recycled products. He projected a 27% energy savings over a typical plant, with 30% less water usage.

Getting involved

“Our work at Virginia Tech was by invitation from William Trefz [of Trefz Engineering in Horsham, PA], a consultant in the area who we have done chiller plants with before in Pennsylvania,” explained Michael Prifti, FAIA, Principal at BLTa. “He was already on board working at Virginia Tech.”

While originally another large architectural/engineering firm was working with Trefz Engineering on the project, the university soon realized that it needed the expertise of BLTa for this specialized project. “Specifically, the original firm hadn’t dealt with the context of the campus or use of Hokie Stone,” said Prifti. “It was a very industrial thing, which wasn’t going to fly. University leadership turned to Trefz, who, in turn, came to us and said he was up against a tight timeline.”

According to Prifti, the firm put together a team with designer John Bower, Jr., FAIA, Emeritus Principal at BLTa. “We put material together to secure Board of Trustees approval,” he said. “We were invited to the team and then responsible for the aesthetic design of the chiller plant. Our partners flew right down and were working non-stop for two weeks.

“The key, obviously, is the brilliant use of Hokie Stone,” Prifti went on to say. “What is basically a mammoth opaque box fits into context. This will be in the mix of buildings that are coming.”

Designing the plant

The new chiller plant is built on a site adjacent to a large surface parking lot. It featured an initial construction phase encompassing 12,000 gross square feet, an installed capacity of 9,000 tons and a construction budget of $16 million — excluding site work. The anticipated full built-out is 21,000 gross square feet with a 15,000-ton capacity. The design was configured, articulated and detailed to subdivide the building’s mass and conceal the large rooftop equipment as well as to better integrate into the campus context, according to BLTa.

Sound control also had to be considered. “There are machines the size of large trucks that compress refrigerant,” explained Prifti. “As it expands, it cools. Inside, the guts are extremely loud. They need great acoustical control.”

And of course, aesthetics were a top priority. Because of the plant’s tremendous size, it was important that it fit with the look of the new architecture to come. In addition to Hokie Stone, precast concrete was also employed in the design.


“ An interesting thing about Hokie Stone is that there’s a lot of variation. Over the last 100 years of building [on campus], the buildings look a little different.  "

---  Michael Prifti, FAIA, Principal at BLTa

“Hokie Stone was mostly on the lower portion of the facade,” said Aronson. “Each level is two stories high. One of the challenges from the aesthetic design was how to integrate the Hokie Stone and precast panels that make the roof screen.”

Consideration was also given to each side of the building during the design phase. “Every side is different,” explained Aronson. “The front faces the campus, so it has a double panel of Hokie Stone. In the future, one side will be up against a parking garage. Also, the chiller plant can double in size, if need be, so the fourth wall is a short wall. You don’t see it from campus. A temporary wall is covered with green screen — very lightweight metal rods. It is very strong and can hold up plants that grow up from the ground. It is covered with greenery, and will be taken down when it is time for the expansion.”

Building with Hokie Stone

Hokie Stone is a dolomite, found in the Appalachian Mountains and most prevalent in Virginia, Tennessee and Alabama. It is a sedimentary rock formed from calcium and magnesium carbonate and occurs in muted shades of pink, red, gray, brown and black. The University quarry stretches across 40 acres and provides 80% of the stone used in campus construction at Virginia Tech. To manage variations in color, the University purchases the remaining 20% from a farm in Montgomery County, but Virginia Tech quarry employees process it.

Geological and environmental changes have resulted in color variations of the stone. The older pinkish dolomites were formed during an era when the region faced an arid, desert-like climate that had a bleaching effect on the rocks. The shades of darker gray and black come from a time of swampy and wetter conditions.

“An interesting thing about Hokie Stone is that there’s a lot of variation,” said Prifti. “Over the last 100 years of building [on campus], the buildings look a little different. They are taking stone out [of the quarry] now that wasn’t in the earlier projects. The new stone is an interesting variation compared to the stone that has been weathering for 50 years. There are some gold highlights that appear when the sun comes around the corner and the stone catches the light. It is a very exciting variation. There are also some dark purple and black highlights.”

Each piece of Hokie Stone used for the chiller plant measured between 4 to 8 inches thick. Samples were brought from the quarry and a large mock-up wall spanning 10 feet high x 10 feet wide was put up. According to the architects, careful consideration was taken in selecting a mortar color that would be appropriate for the design.

Completing the project

In total, the design portion of the project took about a year and a half. “The University was very involved,” said Aronson. “The University Architect has a very good eye for detail. He looked with us at the quality of workmanship. He was very hands-on.”

Construction of the new chiller plant was ahead of schedule. It was finished in 13 months, while it had been projected for 15 months. “LEED is also a unique part of the story,” said Prifti. “I don’t know if there are any campus chiller plants that are LEED. Hokie Stone contributed since it is a local material and high-dollar value. We got exemplary material. The precast plant is also within 500 miles.

“This is a new campus — sending forth on a new bold statement,” Prifti went on to say. “It will serve a half-dozen buildings. We had to put our best foot forward.”    

Chiller Plant — Virginia Tech

Blacksburg, VA

Design Consultant: BLT Architects, Philadelphia, PA
Engineer: Trefz Engineering, Horsham, PA
Engineer and Architect of Record: Burns & Roe Enterprises, Inc., Mount Laurel, NJ


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