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2017WinterShotcreteEMag

Fig. 3: Openings are made to the dome shell, which allow light to enter the completed office Fig. 4: An innovative system of piping runs throughout the shotcrete Fig. 2: Workers apply shotcrete to form the thin shell look of freshly placed green concrete. Similar porcelain tile has a life expectancy of more than 100 years. A PVC membrane doubles as the air-supported concrete form and a single-ply membrane waterproofing system over the entire concrete shell. Three inches (75 mm) of polyurethane form provides superior insulation for the building. In addition to economically protecting against thermal gain or loss of the interior of the building, it protects the concrete shell from thermal stresses induced by uneven radiant heat gain from the sun. Burns Concrete of Idaho Falls, ID, provided the shotcrete for the project, an easy choice based on a long-term working relationship between the two companies. “They have a good understanding of technical shotcrete mix designs, so they fit our style of construction very well, and they have good quality-control measures in place,” Wheeler said. The interior surface of the shell was rodded and troweled smooth, leaving a beautiful 7500 psi (52 MPa) shotcrete finish that will be long lasting and durable. Perhaps the most remarkable features of the building that are not obvious are the heating and cooling systems, both of which are housed within the shotcrete and the concrete. All heating is achieved through in-floor radiant heat with hot water routed through the floor in multiple zones for flexibility in climate control. The innovative cooling system is radiant too. According to Justin Judy, a Principal at Engineering Systems Solutions (ES2) who performed engineering on the project, cooling begins with the concrete shell absorbing heat. “As lights are turned on, as people are in the building, and as computers are turned on, that heat rises, and the shell acts as a thermal battery. It essentially collects that heat, so you don’t necessarily have to air condition the building because the heat is going into the shell,” Judy said. Because the shell holds heat exceptionally well, coming up with a way to discharge the energy was necessary. The ES2 team designed a system that circulates 55°F (13°C) ground water from an exterior well through 3 miles (5 km) of PVC tubing routed within the shell. As the water flows through the shell, it collects the heat, then is dumped into an injection well outside. “We aren’t paying to air-condition a large portion of the dome because we’re using groundwater to do it,” Judy said. Besides long-term cost savings, the heating system provides an ideal work environment for employees. “Particularly with all the openings we have, it’s pretty remarkable we can stay as warm as we do with just the radiant heating,” said Dome Technology Vice President of Sales, Rod South. “Because the dome shell and the floor are integrated into one concrete thermal mass and we have the radiant heating throughout, it stays nice and toasty through the winters,” which can dip to –20°F (–29°C). The heating and cooling systems provide an effective way to show potential customers the efficiency of heating www.shotcrete.org Winter 2017 | Shotcrete 47


2017WinterShotcreteEMag
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