Solar-Powered SunCoolers Keep Food Cool

Stand-alone rooftop ventilators help cool massive U.S. military food warehouse

Solar-powered, rooftop-mounted ventilation units developed with early support from Oregon BEST and testing by researchers at Oregon State University and Oregon Tech are helping the Defense Logistics Agency (DLA) ensure that food stored in a cavernous California warehouse stays cool.

SunCooler™ Ventilators, manufactured by Northwest Renewable Energy Corp. (NWREC), exhaust hot air from buildings during the day, induct cool air inside during the night and can help to de-stratify layers of air inside buildings.

The company recently installed 20 SunCooler units (shown, below, staged before installation) on the rooftop of an 85,000-square-foot warehouse at the Defense Logistics Agency's distribution center in Tracy, Calif., where heat-and-serve meals are stored on pallets.

Staging SunCoolers before installationWhen temperatures inside the building exceed 80 degrees F, the shelf life of the food can be shortened, requiring earlier-than-planned distribution.

Installation was simplified because the SunCooler units replaced some of the existing passive gravity vent hoods on the high-volume, 63-foot-tall building. And because each SunCooler is solar powered and can be controlled and monitored via a wireless network, no electrical or plumbing work was required.

"Historically, inside this building, they have used swamp coolers the size of VW bugs on carts to reduce the temperature on hot days," said Jason Wright, CEO of NWREC. "But those swamp coolers require extension cords and water hoses, and increase the humidity inside the building."

The U.S. Dept. of Defense has been mandated to reduce energy use by 2.5 percent per year for next 10 years. The DLA sources and provides the consumable items U.S. military forces need to operate – from food and fuel to medical supplies and construction materials.

The SunCooler units on the DLA warehouse are programed to monitor the outdoor air temperature between 1 a.m. and 6 a.m.. When the temperature falls to between 65 and 40 F, fans in the units induce the cooler air into the building, where it falls toward the floor.

From 12 noon until 8 p.m., the SunCooler units are programmed to monitor the building's interior temperature, and when that nears 80 degrees at the ceiling, the units exhaust the warm air out of the building.

"So our units are covering both daytime exhaust cooling and nighttime flush induction cooling, which are very important in facilities like this where food is stored," Wright said.

Wide version of SunCoolerThe technology, which can be deployed in different sizes (larger model, shown right) is also attracting attention from customers that include the federal prison system, big box store warehouses, modular classrooms and others.

"A lot of our installations replace grid-powered roof exhaust fans, and the instant those fans are unplugged, the customer is saving energy dollars," Wright said. "With some five million commercial buildings in the United States, and HVAC systems in those buildings consuming more than 50 percent of the energy used, there is great potential for increased energy savings with our technology."

A grant from Oregon BEST funded early testing of SunCooler units by on a building at Oregon Tech’s Klamath Falls campus, and an Oregon BEST investment supported additional validation research at OSU.

An early grant from Oregon BEST funded proof-of-concept testing of SunCooler units on a building at Oregon Tech’s Klamath Falls campus, and a recent investment by Oregon BEST supported validation testing by OSU researchers at a large regional distribution center.

"It's exciting to watch this technology beginning to gain traction and save energy use in buildings," said David Kenney, President and Executive Director of Oregon BEST. "We are proud to have played a role in helping the company utilize university researchers to speed development and validate the technology."