The fabric cladding on the south facing gable wall of Rubb’s 14,500 sq ft Steel Shop was replaced with a 4-inch, air plenum standing seam Polycarbonate glazing system, which harvests solar heat in the form of hot air. The solar heat, which delivers more than 8,000cfm of air volume at +100°F, is distributed evenly throughout the 14,500 sq ft building via a fabric ductwork system. The system can be incorporated into a new structure or easily retro-fitted onto an existing Rubb building.
Combined with the highly efficient Rubb Thermohall® insulation system, the overall result is an employee-friendly warm environment, significant energy savings and a forward thinking green solution. The overall solution, in partnership with Shift Energy, is achieving an estimated five-year payback against natural gas, due also in part to the efficiency of circulating trapped air and storing heat using thermal mass. This is the unique part of the Rubb/Shift solution.
Winters in southern Maine are extremely cold and snowy, yet on a sunny, early March morning, with sub-freezing temperatures outside, it was a balmy 75°F (24°C) inside the 24.4m (80ft) x 54.9m (180ft) Rubb Thermohall® insulated structure; and the heating system was not on.
The solar harvesting system has been automated into a thermostat ‘microcontroller’ system which detects the amount of energy (heat) being generated by the solar wall and adjusts the building’s mechanical system accordingly. Performance data has been gathered hourly on the system, helping track the benefits of the Solar Harvesting system and the overall holistic building solution. Early results show the combination of Shift’s solar heat plus Rubb’s high performance envelope is achieving very close to net-zero heating in an extremely cold climate. In support of Rubb’s innovation, Efficiency Maine’s Commercial & Industrial Incentive program also helped make the project possible, awarding Rubb with funding for a portion of the project.