The 134,511-square-foot cold storage building for Innovative Cold Storage Enterprises Inc. (ICE) of San Diego was a collaborative effort spearheaded by El Cajon, Calif.-based Hamman Companies, SunPower Corp. of San Jose, ICE, and San Diego Gas & Electric (SDG&E). It took a 10-person design team and more than 40 subcontractors to address and resolve the challenges present in creating a LEED-compliant, solar-powered, energy-efficient cold storage facility.
C&L Refrigeration was called in to resolve refrigeration challenges involving the building design, integration of the refrigeration system with the solar panels, and handling wastewater generated from the refrigeration system. C&L stepped up to the plate.
Challenges & solutions
Challenge: A 60-foot ceiling height was 25 feet taller than is typical for cold storage facilities. That meant the evaporators-usually suspended from the ceiling-would have to be moved in order to be more accessible for maintenance.
Solution: C&L designed “penthouses” on the roof for the evaporators. Having the evaporators on the roof allowed for easy access for maintenance. It also allowed for having just a few large evaporators rather than many small evaporators.
Challenge: Reducing heat load to attain a 75% more efficient building.
Solution: “Going vertical was very important, because there's the same square footage on the roof but more storage space inside,” said C&L project engineer Tom Dosch, PE. Because the roof is the biggest source of heat and 90% of a cold storage facility's energy bill comes from refrigeration, having more storage space without increasing the size of the roof reduces the overall power needs.
Challenge: The solar panels on the roof needed to provide the power for the refrigeration system during the hottest part of the day.
Solution: The C&L refrigeration control system is integrated with the solar panel control system. During the hottest part of the day when energy is most expensive, the refrigeration output is lowered to meet the available power from the solar panels. This is accomplished by adjusting the frequency on variable speed drives of each compressor.
Challenge: Minimize water usage and recycle wastewater.
Solution: C&L designed a way to minimize the amount of water used from the cooling tower and devised a plan to store and use wastewater for irrigation, saving about 42,000 gallons of water each month. Then they designed a way to store the defrost water from the evaporators and use it to operate the building's low-volume toilets.
Challenge: Leave a smaller carbon footprint.
Solution: C&L chose high-efficiency ammonia screw compressors instead of the more common Freon, which is ozone-depleting. Ammonia, a naturally occurring compound, has zero ozone depletion potential, Dosch said.
The result of these and other efforts by the team will be to:
- Reduce energy costs by about 75 percent by producing the majority of the energy with solar panels. This also reduces CO2 emissions.
- Provide more storage capacity (6.5 million cubic feet) using less power. Because ICE II has another, older cold storage building, it will be possible to compare energy usage. The new building is expected to store four times as much product at half the cost of ICE's first building.
C&L plans to leverage its experience with this cold storage facility to other applications for clients. The company will seek ways to apply LEED standards to existing buildings and maintenance efficiencies as well as to new construction. “There's a good future in green technology for industrial applications and we're committed to being a leader in that,” Cassell said. “Customers always have wanted us to innovate and be more efficient.”