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March 2013
Urban Eden
By Pete Prunkl

     Americans invented the solar cell, wind turbine and lithium battery. Not a bad start in the highly competitive, alternative energy marketplace. While the U.S. earns points for genius, our impact on society has been tepid at best. For example: solar power. It is a free, renewable, clean and seemingly inexhaustible resource. Why isn’t the sun America’s primary source of power?

     The poet T.S. Eliot knew the answer. “Between the idea and the reality, between the motion and the act,” he said, “there falls a shadow.”

     An enormous portion of the solar shadow is cost. A few years ago real estate agent Binnie Orrell investigated running his Charlotte home entirely on solar power. He received an estimate of $25,000 to install a single photovoltaic (PV) solar panel on the roof. “It was absurd,” comments Orrell.

     “Prices for photovoltaic systems that generate electricity have dropped dramatically in the past few years,” says solar energy engineer Tommy Cleveland of the North Carolina Solar Center. “A quote today would be half of what it was three to four years ago.”

     Part of the reason for the price reduction is the Chinese government. When they decided to subsidize solar panel production, other manufacturers like Bosch Solar in Mooresville, quickly dropped their prices.

     Tommy Cleveland adds another solar fact of life: “It costs more to retrofit a house for solar than new construction.”

 

Making Solar Work

     But it’s more than cost that deters homeowners and businesses from taking advantage of free energy. There are many other factors to consider before Americans will demand a house that transforms solar potential into solar power.

     In fact, the Department of Energy has defined them as the ability to deliver on a set of 10 criteria: Architecture, Market Appeal, Engineering, Communications, Affordability, Comfort Zone, Hot Water, Appliances, Home Entertainment, Energy Balance. 

     That challenge to meet those criteria is the impetus behind their biennial Solar Decathlon competition, to design, build and operate the smartest solar home on the planet.

     For the past 10 years teams from colleges and universities from the United States, Canada, Spain, Puerto Rico, Belgium, China, Germany and New Zealand have vied for trophies—one for each solar criteria—plus the mega trophy for the overall best-of-show house. Similar to their counterparts in the Olympics, these engineering, architecture and business students refer to themselves as “decathletes.”

     This is the second time the University of North Carolina at Charlotte has been selected to compete in the Solar Decathlon. Their first solar house was built for the 2002 competition where the Charlotte decathletes finished 13th out of 14 teams.

     “We made rookie errors,” says Benjamin Futrell, project manager for the 2013 Solar Decathlon. “We expect to do much better this time.”

     The only other North Carolina team that has ever participated was Appalachian State University in 2011. They accumulated 832 points out of 1,000 and came in 11th out of 20 teams.

     Solar Decathlon Director Richard King visited UNC Charlotte for the symbolic groundbreaking for Urban Eden, the school’s entry in the 2013 competition. King, who works in Washington, D.C., has great affection for UNC Charlotte. He views the 49ers as pioneers, joining the Solar Decathlon in its inaugural year at a time when King wondered if any university would accept his challenging and expensive invitation.

 

The Competition

     Of the 20 teams in the 2013 Solar Decathlon competition, six are repeat players including UNC Charlotte. With five appearances, Missouri University of Science and Technology from Rolla has the most Solar Decathlon experience. But the Rolla team has never finished in the top three. The toughest competitors are expected to come from four California schools. Santa Clara University has taken third place twice in its three appearances. The Broncos are itching for first in 2013.

     The team of Southern California Institute of Architecture (known as Sci-ARC) and California Institute of Technology have been to two competitions and never finished in the top three, but they head Futrell’s list of teams to beat. Rounding out the West Coast roster are Stanford University and the University of Southern California, both rookies.

     The California schools come to the competition from a solar friendly culture. California is the nation’s largest solar energy market by far and has effective state initiatives that promote the industry.

     Solar Decathlon homes use state-of-the-art photovoltaic panels or modules to generate their own electricity. The panels coupled with energy-saving construction materials are enough to power lights, stove, entertainment system, heating and air conditioning, as well as a washer and dryer.

     The goal is for each home to generate all the energy it needs during the 10-day competition. Solar engineers call this net metering and it garners points for the Energy Balance criteria.

     The homes also use passive solar systems, typically for winter space-heating. They include collectors, absorbers, a thermal mass to store heat, ducts to move the heat, and controllers such as a roof overhang to reduce heat. Passive solar shuns all active features; there are no blowers or fans to circulate the air.

     In between these two extremes are solar systems used only for heating hot water. This is a far more limited use of solar power than PV or passive. China may be the world’s leader in solar water heaters, producing the most efficient, inexpensive and widely-adopted units.

     Contrary to earlier competitions, the 2013 Solar Decathlon homes are not stand-alone solar systems. They are designed to be connected to the Village Grid, a mini-electrical system paid for by the Department of Energy and set up just for the decathlon.

     That was not the case in the first three decathlons. For 2002, 2005 and 2007, the homes included battery packs to store electricity for nighttime use. These homes were independent of the utility company and truly “off the grid.”

     That arrangement changed for 2009 and thereafter because, says King, “Ninety-nine percent of solar homes built today are tied to the grid.”

     Grid-tied homes have become popular. Even with state-of-the-art photovoltaic panels and a save-the-environment outlook, solar enthusiasts want the grid as a nighttime backup. The grid also helps when the home creates more energy than it needs. Equipped with a bidirectional meter, consumers get credit for electricity they put on the grid, i.e. when the meter runs backwards. Like the rest of us, when the meter runs forward, they pay for the energy they take off the grid.

     In a perfect world and with a smart-sized house, the result would be net metering. This perfect state is what earns decathletes 100 points for Energy Balance.

     All homes in the decathlon have something else in common: a target audience. Each team identifies a group in its locale that could most benefit from a solar house. Choosing the target audience helps frame and focus the design.

     For the Czech team, its inhabitants are a 50+ years older couple looking for a weekend escape to the country. Team Texas designed its home for the modern desert dweller. Team Alberta envisioned modular housing for mining teams in remote areas of Canada. The schools from the District of Columbia are designing a home for returning disabled veterans.

     UNC Charlotte’s team has two Charlotte couples in mind: “empty nesters” and a two-income professional couple with no children or DINKS, double income—no kids. They imagine Urban Eden as an infill house on one of Charlotte’s vacant lots, in older neighborhoods or in redevelopment areas. That’s the urban part. A peaceful outdoor garden that connects to the indoor space serves as its Eden.

 

The Secret Weapon

     A few teams have what they tout as a secret weapon—a design component that raises the bar, advances the field and wins points. For Santa Clara, it’s bamboo. The entire structure of their Radiant House will be made from this sustainable plant. The UNC Charlotte house has a double-barreled secret weapon built right into its walls.

     “This is likely going to be the first geopolymer cement concrete house ever constructed,” boasts Dr. Brett Tempest of UNC Charlotte’s Civil and Environmental Engineering Department. This alternative form of concrete is made with fly ash, a waste product created when coal is burned. When hardened it has a similar mechanical characteristics to the widely used Portland cement, an ingredient in concrete.

     “Manufacturing Portland cement accounts for approximately 10 percent of global greenhouse gas emissions,” says Tempest. “Geopolymer completely replaces the need for Portland cement in the concrete for the house and that decreases the carbon associated with traditional concrete manufacturing by 90 percent. This new material has uniformity, consistency and durability.”

     Additionally it repurposes fly ash, a byproduct of coal power production. If fly ash were not used as a new building material, this residue would end up in a landfill.

     “Replacing Portland cement with geopolymers is really just a plug-and-play thing. It’s not like you have to do any major conceptual or technical changes to the way you implement the concerete. We just solved a major problem in the world by implementing this one thing,” says Clark Snell, the student project manager for Urban Eden.

     The second part of Urban Eden’s one-two punch is derived from a network of capillary tubes embedded into the fly ash concrete. “This blue plastic mesh allows us to control the heat that is built up in the walls of the house,” explains Futrell. Using a pump, the heated water is transported from the walls to the roof where it is dissipated into the night air.

     In a traditional passive solar system, a thermal mass, such as water or bricks, cools on its own at night. The combination of tubing, water pump and roof membrane is the real secret weapon. “It revolutionizes passive solar heating and cooling,” says Snell.

 

Making It Possible

     Although it is only one of the 10 Solar Decathlon criteria, student builders work hard to keep the total construction cost of their homes at or under $250,000. That is the magic number for the affordability criteria and it’s a new upper limit for the 2013 competition. This year, teams lose points by going over $250,000.

     “If the house costs over $600,000, no points are awarded for affordability,” says King, adding, “It is easier to be innovative, but harder to be cost effective.”

     Affordability is a juried competition. Construction experts estimate the cost of each component as well as total construction expense.

     UNC Charlotte expects that the entire project from focus groups and student stipends to building, transporting and reassembling the home in Irvine, Calif., will be in the neighborhood of $1.2 million. The Department of Energy gave each 2013 team $100,000 and UNC Charlotte contributed another $375,000. That leaves a sizable chunk for the team’s sponsors.

     Ingersoll Rand, Bosch Solar, Electrolux, Edifice, Intus Windows and SteelFab made up the shortfall with cash and in-kind donations. Electrolux will be supplying the washer and dryer while the refrigerator comes from Blomberg, a German manufacturer with multiple minimum energy consumption awards. For Urban Eden’s sliding roof, Bosch Solar will donate a complete array of 255-watt photovoltaic monocrystalline solar panels. Each of the 36 German-manufactured panels retails for $300.

     Construction of Urban Eden began in mid-February inside the massive EPIC Building at the Charlotte Research Institute. As the weather warms and Urban Eden expands, it will be brought outside. When complete it will be disassembled and shipped to Orange County Great Park, where it will be reassembled as part of the Solar Decathlon village.

     The California site is another first for the 2013 Decathlon. In previous years the village was constructed on the National Mall in Washington, D.C., between the Lincoln Memorial and the United States Capitol. This year it’s halfway between Los Angeles and San Diego on the site of the former El Toro Air Station. As the original 49ers said, “California, here we come!”

     The competition runs from October 3 to 13 and is open to the public for eight of its 10 days. The overall winner is announced during closing ceremonies.

     The Solar Decathlon serves to bring the best of education and industry together for the common goal of sustainability, inspiring innovation and efficiency and well as engendering camaraderie and health competition. Its byproducts spur scientists, production specialists, grid engineers, municipal planners, and countless others to focus on using nature’s free energy inexpensively and efficiently.

      Together, academia and business acumen combine to bring new discoveries and innovation to the commercial marketplace. It is precisely this type of synergy that creates wealth and opportunity, including job creation, helping us to compete in the global marketplace.

     Perhaps the greatest benefit of Urban Eden will occur after it returns to the UNC Charlotte campus for public viewing. Perhaps a couple of empty nesters or DINKS will see it and decide to replicate it on a Charlotte vacant lot. If they invest $250,000 in their new home, in the course of the next 30 years they’ll save an average of $72,000 in utility bills. Some of that time, their electrical meter will run forward and they will pay for electricity. But on sunny days, their meter will run backwards to the future.

     Go Niners!

 

Pete Prunkl is a Greater Charlotte Biz freelance writer.
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