Solar Decathlon Build-out Gathers Pace
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First report from the National Mall
With the Solar Decathlon only a couple of days away, Solar Nation brings you the first of a series of eyewitness reports from the solar village on the National Mall in Washington DC. Today, we look at an unusually-shaped entry from Cornell University.
The sun rose this morning on a new development in progress in downtown Washington -- about as downtown as you can get, in fact. On the National Mall, stretching from the Washington Monument east to the Smithsonian 'Castle', twenty small houses were in different stages of construction. They had started their journey to the capital from points as far away as Darmstadt, Germany and as close as the state of Virginia, to compete in the 2009 Solar Decathlon.
The houses, all designed and constructed by university teams from the U.S., Canada, Puerto Rico, Spain and Germany, have been under construction since the first of the month. And at 1pm on Thursday, Energy Secretary Steven Chu will officially open the event and the houses will begin to be judged in these ten contests:
* architecture
* market viability
* engineering
* lighting design
* communications
* comfort zone
* hot water
* appliances
* home entertainment
* net metering
I took my first look at the 'solar village' as it took shape in the early morning shadow of the U.S. Capitol. Some intriguing and innovative designs were on show, and perhaps none more intriguing than that of Cornell University. The shape of Cornell's 800-square-foot house brings to mind the grain silos typical of the university's upper New York State location (appropriately, it's known as the Silo House), but these silos support an 8-kW PV array and are clad with five inches of soy-based spray foam for insulation. In back of the house are two arrays of evacuated tubes, which use a water glycol heat transfer medium to provide domestic hot water and warm air for heating.
Part of the shape of things to come in the Silo House is the home control system, which anticipates an interactive smart grid. The system, by Computerized Electricity Systems, allows residents to monitor power use in real time through an Internet connection. It can turn devices on and off remotely, by program or by manual command, and with reference to the actual hourly cost of electricity. This capability is clearly intended to work with an electric grid of the future, in which home systems and appliances influence and are influenced by the utility power supply. And in a net-zero building like the Silo House, it can optimize the output of the PV and solar thermal systems.
I noticed that, unlike most of the other buildings, Cornell's entry seemed to skimp on sunlighting, i.e., using large windows to maximize passive solar benefits. But Sam Sinensky, an engineering sophomore, said: "we depend for sunlighting on a floor-to-ceiling wall of glass, which also serves as an entryway. The glass is double-paned and filled with Argon with a r factor of 5."
The path to the Silo House crosses an expanse of hydroponically grown grasses, which help to fillter grey water from the building. Each of the three 'silos' making up the living space -- kitchen, living room and bedroom -- contains several sensors for temperature and humidity, all feeding into a central system that regulates living conditions inside the building envelope.
When you see Cornell's house, your first reaction could be to wonder why the students used rusty corrugated iron for their walls. In fact, the material is COR-TEN, a steel cladding that loses its sheen by design, as the outer layer oxidizes to a weather-proof ruddy-colored coating.
Cornell has come in with a strong contender for the grand prize of the Solar Decathlon, but all the students involved know that there are nineteen other buildings, probably just as good, that theirs will have to beat for that silver trophy.
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