Bioenergy, Energy Efficiency

Cool Collaboration Mines Forgotten Technologies for Huge Energy Savings

Author Pat Choate has for decades warned of the dire consequences of America losing its manufacturing base through outsourcing and financialization of the economy. He points to Germany — conventionally dismissed as stagnant in both growth and innovation — as the example the U.S. should follow.

By many measures, including trade and renewable energy growth, Germany leads the U.S.  A key advantage of German manufacturing, he notes, are the close links between manufacturing and universities.

This seems to be changing in the U.S. as many universities are finding opportunities in renewable and carbon efficient energy.  The University of California at Davis has several collaborating centers specializing in cooling, lighting, efficiency, solar, and biomass energy.  Others are planned. 

The Western Cooling Efficiency Center at the UCDavis works with 22 partners, almost all in the private sector, to perfect and bring to market more efficient cooling technologies. 

The prize for the hot dry climates of the globe is an estimated 40% reduction in peak demand and another 40% for overall energy use. (Some estimates are north of 80%.)  For business, the prize is access to the vast market for new and replacement cooling systems in the current stock of buildings.

The engineers at WCEC have zeroed in on a group of technologies that are well suited to dry western climates, particularly those that are overlooked in the current market.  One focus is on a new generation of evaporative cooling that, unlike the old swamp coolers, which add moisture, mildew, allergens and bacteria to the indoors, add little or no moisture to inside air, typically double energy efficiency, and provide more cooling in the hottest weather.

The latter is important as the requirements for new refrigerants to replace the old environmentally-unfriendly conventional R-22 refrigerant this year.   Mark Modera, the director of WCEC, estimates that the new refrigerant have almost twice sensitivity to outdoor temperature as R-22, which loses about 1% of its cooling efficiency for each degree Farenheit increase in outdoor temperature.. 

There are three types of evaporative-only coolers: direct, indirect, and 2-stage. Direct coolers use a media that evaporates the water directly into the air. Indirect coolers use two air streams to avoid adding moisture to the cooled air, providing cool, dry air.  2-Stage systems (also known as direct-indirect units) use a direct media as well as an indirect heat exchanger, thereby creating cooler air at a lower temperature and lower humidity level as compared to direct-only coolers.

WCEC’s  portfolio also includes vapor compression and  radiant-cooling technologies, as well as hybrids of the various options.

Here’s a sampling of some of the products that the WCEC collaboration has improved or developed from scratch:

Coolerado’s rooftop is an indirect evaporative cooler that uses a patented heat and mass exchanger (HMX) and cools the supply air in twenty stages. At each stage the humidified air is exhausted and enhances the cooling effect of the supply air.  Coolerado’s unit is the first to be tested by the U.S. Department of Energy and certified as meeting the WCEC’s Western Cooling Challenge.  Starting at around $10,000, the unit was named by Popular Mechanics as among “the best of what’s new in 2009.”

AquaCool, by the big HVAC contractor Beutler, has efficiency that changes little even as the temperature tops 100 degrees. The Sacramento Municipal Utility District (SMUD) has tested it in homes in several new housing divisions in Sacramento. 

Integrated Comfort, Inc., which manufactures and markets the DualCool, an accessory for packaged rooftop units (RTUs) that evaporatively cools condenser air to reduce condensing temperatures, and also pre-cools ventilation air to reduce building cooling loads. DualCool is a retrofittable system that typically reduces the energy use and peak demand of rooftop cooling units by 30% in dry climates. The company also markets Night Sky, a system that radiates heat to the cool night sky.  When fully integrated into new buildings, it can reduce energy use and peak demand by up to 80% in dry climates.    

The principle of DualCool, says Richard Bourne, one of its developers, is that the retrofit “fools the unit into thinking its in 75 degree heat instead of 110.  There is further opportunity is pre-cooling the ventilation air.”   Bourne, the founding director of WCEC, is now retired but active in the private sector.

The Speakman Company, founded in 1869 as a plumbing pipe-fitting company, manufactures the OASys, a patented two stage evaporative cooling unit that produces up to 3.5 tons of sensible cooling while using less than 600 watts for an energy efficiency equivalent to better than 40 SEER (sensible energy efficiency rating).  The best conventional units on the market are only 17 SEER.

Ice Energy manufactures and markets a an ice storage air conditioning system that shifts the largest component of residential and commercial peak demand — air conditioning — from expensive “on-peak” times of the day to “off-peak” periods, when energy is less expensive and less polluting. The Ice Bear‘s refrigerant management system reduces peak demand by 95% while maintaining or improving overall building energy performance. The flagship Ice Bear 50 product was named the Energy Management Product of the Year in 2004 at the AHR (air conditioning, heating, and refrigeration) Expo.

 Munters, the Swedish manufacturer of energy efficient air treatment solutions that control humidity and temperature, recover energy, and/or use direct or indirect evaporative cooling for comfort, process and environmental protection.

Seeley International is an Australian manufacturer of heating and cooling equipment for energy efficient climate control solutions. It has developed the Breezair Icon evaporative air conditioner, which uses up to 40 percent less electricity than conventional ducted evaporative air conditioning systems. Other new innovations include the energy efficient Stealth fan technology, Smart Water Management technology, and the Tri-Action heat exchanger.

Radiant heating and cooling are represented  by two companies, Uponor and Viega. Viega makes the ProPress copper press fitting system, PureFlow PEX plumbing systems, ProRadiant hydronic heating systems and the new Climate Mat pre-fabricated radiant cooling assembly.  Uponor was a pioneer in Europe of the underfloor heating industry three decades ago. 

“Radiant cooling can keep people cool at higher air temperatures” says Mark Modera, the current WCEC director. “An installation at WalMart in south Sacramento is projected to save 60 to 70% of cooling energy, and the same system can, of course, be used for heating.”

In dry western climates, water is as big an issue as energy.

“Evaporative coolers use water, but well-designed, modern coolers use a batch flushing process to clean the sump rather than a continuous bleeding technique,” writes Larry Kinney at HomeEnergy.org.   “The result is better cleaning and substantially lower water use. Modern coolers in efficient homes in the Southwest use an average of 5,750 gallons of water per year, about 3.3% of average annual residential water use.

This amount of water costs $5 to $20 per cooling season. However, since evaporative coolers save on the order of 3,600 kWh per year, about 1,810 gallons of water are saved at the power station on average in the Southwest, for a net water use of evaporative cooling of 3,940 gallons.”   Madera concedes that water is a problem.  He thinks recycling the water as gray water irrigation or using stored rainwater could be an answer.