Thermal Energy Storage Freezes Bills, Cuts Daytime Consumption
by Richard Holzer, P.E., LEED AP, Glumac Irvine Managing Principal
Extron Electronics was able to earn a $615,000 municipal rebate against power bills at the company’s new headquarters in Anaheim, thanks to a thermal energy storage (TES) system Glumac engineered, commissioned and tested.
Completed in December, 2011, Extron's new headquarters is a six-story, 194,000 sf mixed-use office tower building that includes a restaurant and music venue on the ground floor, administrative offices on the middle floors, and a penthouse residential suite on the top floor. Given the climate of the region, cooling the building often requires a great deal of electricity, especially during peak demand hours (summer afternoons).
The City of Anaheim offers rebates to incentivize large companies to develop systems to shift their energy consumption to off-peak hours. By leveling demand, such switching helps the city avoid the expense of buying more expensive power or expanding power plant capacity.
Extron decided to take the City up on its offer, and invested in a new TES system. The concept behind TES is quite simple: a 300-ton chiller manufactures ice—and thus consumes increased city-generated electricity—at night, during off-peak demand hours. The ice is stored in five ground-level ice tanks, each holding 33,500 gallons of frozen water. During the daytime, the ice is used to chill air in the building, relieving the power load on operating air conditioners.
Though simple in theory, the actual engineering, installation, and testing of the system required focused expertise and careful execution to ensure it was completed correctly and within budget. Engineering the TES system was only step one; using Trane’s Trace 700 software, Glumac then worked to evalute various options that would be cost-effective, given the City of Anaheim’s rate and rebate structures, and presented Extron with our recommended choices. Glumac and Extron ended up considering twelve different TES systems before going to a final selection. Glumac's commissioning scope included supervision and testing of the selected TES system during and after construction.
Glumac was retained to provide full MEP design and commissioning services for the balance of the mixed-use headquarters as well. In the end, Glumac's work at Extron was a success story in terms of both engineering and economics. Glumac looks forward to utilizing more applications of TES as electrical utilities move to “real-time pricing,” where higher daytime utility rates challenge building owners to improve the energy efficiency of their buildings.