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The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the monthly PCM newsletter. Or join the discussion on LinkedIn.




Cal Poly's Solar Decathlon entry uses biobased PCM to reduce heating, cooling costs

Ben Welter - Wednesday, June 10, 2015

California Polytechnic's entry in Solar Decathlon 2015 features an open design that takes advantage of the mild climate on the Pacific Coast. Team member Lisa-Marie Mueller describes INhouse as a "coastal home that is true to that climate and the very unique indoor-outdoor living that we have here year-round."

The house, now under construction in San Luis Obispo, uses a variety of energy- and space-saving techniques:

• A 15-foot glass wall separating the living room and deck can be folded back to create an indoor-outdoor living space.

• Two-sided photovoltaic panels serve as an awning above the deck, providing shade and capturing 30 percent more energy than a single layer of PV.

• Biobased phase change material is used in the home's ductwork to reduce heating and cooling costs.

The Solar Decathlon, sponsored by the U.S. Department of Energy, will take place Oct. 8-18 in Irvine, Calif. Entries will be judged on energy efficiency, design, affordability and consumer appeal.

Researchers outline ambitious plan to run U.S. economy entirely on renewable energy

Ben Welter - Wednesday, June 10, 2015

Would it be possible to run the U.S. economy entirely on renewable energy by 2050? A team of researchers led by Dr. Mark Z. Jacobson of Stanford says yes, and lays out an ambitious and detailed state-by-state plan.'s David Roberts explains:

"The core of the plan is to electrify everything, including sectors that currently run partially or entirely on liquid fossil fuels. That means shifting transportation, heating/cooling, and industry to run on electric power.

"Electrifying everything produces an enormous drop in projected demand, since the energy-to-work conversion of electric motors is much more efficient than combustion motors, which lose a ton of energy to heat. So the amount of energy necessary to meet projected demand drops by a third just from the conversion."

The study, published in Energy & Environmental Science, also sees a role for thermal energy storage, including ice, water and phase change materials, and time-of-use electricity rates that encourage off-peak energy consumption.

Economist says energy efficiency is overlooked factor in measuring productivity

Ben Welter - Tuesday, June 09, 2015

Greentech Media's latest "Energy Gang" podcast includes a segment with Skip Laitner, an economist who says we've been measuring energy productivity all wrong. As measured by all energy available for use, he said, the U.S. economy is running at only 15 percent efficiency. 

Economist Skip Laitner"Whether it's light, whether it's thermal energy, an industrial process, whether it's powering up the Internet or maintaining a cold beer in the refrigerator, what is actually going on as work, to provide the cooling, to provide the heat and provide the light?" said Laitner, right. "When we [measure energy productivity] that way we find that we're wasting more than 80 percent of that energy, and that's nothing but a set of costs that really clamp down on the economy."

In another segment, starting at 25:30, the group talks about the Energy Storage Association's expo in Dallas last month. Among the takeaways: Ice-based storage and phase change material are gaining traction in the discussion of energy storage.

"Storage is everything from batteries all the way through ice storage and thermal storage units, all the way through to some of these phase change materials and other things," said energy futurist Jigar Shah. "I was pitched a couple times by folks who had much different definitions of storage, which I thought was fascinating."

Solar Decathlon entry uses rainwater to shift cooling to off-peak hours

Ben Welter - Friday, June 05, 2015


Builder Online takes an in-depth look at NexusHaus, one of 20 entries in the U.S. Department of Energy's Solar Decathlon 2015. Net zero energy use and water conservation are integral to the house, a co-production of a team of students from the University of Texas, Austin, and Technische Universitat Munchen, Germany. One goal is to reduce peak energy consumption by 80 percent through thermal energy storage. In summer, a rainwater-collecting tank will serve as a thermal storage unit for a system that will shift cooling to off-peak hours. 

"The home will capture enough rainwater to supply all of its potable water needs, although it will be connected to the municipal water supply for backup during long dry spells," Builder Online reports. "Rainwater will hit the 2,000-square-foot canopy between the home's two modules and flow down a system of gutters into under-deck bladder tanks that can hold up to 5,000 gallons. Before being used in the house for drinking, bathing, and clothes and dish washing, the rainwater will be run through a two-state filtration system: a carbon filter for particulates and a UV light filter to treat it to the National Sanitation Foundation's Standard 61 for potable water."

The Solar Decathlon will take place Oct. 8-18 in Irvine, Calif. Entries will be judged on energy efficiency, design, affordability and consumer appeal.

New School's University Center, Federal Center South win AIA sustainability awards

Ben Welter - Thursday, April 23, 2015

New School University CenterThe New School's University Center, a 370,000-square-foot mixed-use building in Manhattan, has made the American Institute of Architects' list of the Top 10 Most Sustainable Projects of 2015. The LEED Gold building, right, features a thermal energy storage system that makes ice at night, when electricity is cheaper, to help cool the structure during the day. University Center was designed by Skidmore, Owings & Merrill.

Federal Center South, a U.S. Army Corps of Engineers office building in Seattle, was honored as the AIA's Top 10 Plus winner. The building's HVAC system includes heat-recovery chillers that extract heat from a thermal storage tank to warm the building in the morning, when demand is high. A rooftop tank is filled with 2-foot-long panels containing phase change material that freezes and thaws at 55 degrees, serving as a battery for storing energy. Federal Center South was designed by ZGF Architects.

New director sought for National Renewable Energy Laboratory

Ben Welter - Wednesday, April 15, 2015

The Alliance for Sustainable Energy is seeking candidates for the position of director of the National Renewable Energy Laboratory in Golden, Colo. The current director, Dr. Dan Arvizu, is retiring this fall. 

Alliance, which manages NREL for the U.S. Department of Energy, is seeking candidates who have "a demonstrated record of inspiring and guiding a research organization toward a compelling vision for impact, proven skill in leading innovation in science and engineering, a track record for delivering high-quality research results that are relevant and impactful, and experience in guiding operational excellence that enables mission accomplishment while meeting contractual requirements."

Utilities can maintain profits while reducing energy consumption, Economist says

Ben Welter - Friday, April 10, 2015

The Economist lists ice-based energy storage systems as among the technologies that can slash energy consumption without dampening economic growth.

"Storing off-peak energy as ice is particularly useful for air-cooling systems, one of the industrialised world’s biggest energy hogs," the Economist notes. "Air conditioning in commercial buildings accounts for about 5% of America’s electricity use. But in some parts of the country, on a hot day, the figure can reach 30%. Cooling systems from Calmac, a firm that used to make furnaces, store energy by cooling water mixed with antifreeze when power is cheap, and release it when it is needed, rather than relying on power-hungry compressors to cool the building during peak daytime hours."

A virtual tour of NYC's passive house movement

Ben Welter - Thursday, April 09, 2015

Map of NYC passive housesCurbed New York has compiled a list of 21 buildings in New York City designed to meet energy-use standards outlined by Germany's Passive House Institute. 

Most of New York's passive houses are in Brooklyn. The list includes 23 Park Place, NYC's first certified passive house; 951 Pacific, a three-unit row house that is aiming for "net zero" status, allowing each homeowner "the possibility of living without eternal power costs"; and 45-12 11th Street, which has been called the ugliest house in Queens. ...

New building at Brussels Airport features seasonal thermal energy storage

Ben Welter - Friday, March 27, 2015

Connector, new building at Brussels Airport

The Connector, an $81 million addition to the Brussels Airport, opened to passengers this week. Seasonal thermal energy storage is among the building's energy-efficient features. The system covers about 70 percent of the energy needed to heat the building and about 30 percent of the energy needed to cool it. Rainwater from the roof is collected in a 177,000-gallon reservoir that supplies water for sanitary use.

Connect with PCM experts and industry leaders on LinkedIn

Ben Welter - Wednesday, March 25, 2015

Phase Change Matters logoNew on LinkedIn: A group devoted to the discussion of phase change material and thermal energy storage, a place for PCM and TES experts and industry leaders from around the world to gather and share ideas. It's called Phase Change Matters, and it's intended as a highly interactive complement to the blog and newsletter of the same name.

The first topic up for discussion: PCM and off-peak cooling systems:

TES pioneers like CALMAC and Ice Energy have been installing ice-based energy storage systems for years. And district cooling has been around for decades. What are the main barriers to wider adoption of phase change material in these types of thermal energy storage systems? Complexity? Education? Cost?

You are invited to join the discussion. Here's a link to the group: