Some tidbits regarding this year's contestants and their designs.
A bird’s-eye view shows
the public touring the international U.S. Department of Energy Solar Decathlon,
featuring energy-efficient, solar-powered homes built by 20 university teams
from North American and Europe, on the National Mall in Washington, D.C., Oct.
13, 2009. (Credit: Stefano Paltera/U.S. Department of Energy Solar
Team Boston member Clay
Larsen installs a rainwater-capturing sculpture that will deliver water to a
fish pond during the U.S. Department of Energy Solar Decathlon 2009 on the
National Mall in Washington, D.C., Oct. 06, 2009. (Credit: Stefano
Paltera/U.S. Department of Energy Solar Decathlon.)
The fourth Solar Decathlon
took place on the
lawn of the National Mall in Washington just a couple weeks ago. As I was
gathering information to write an article on this year’s contest, it struck me
how very few of the solar homes used solar radiant heating systems.
Out of 20 teams, seven had radiant heating and/or
cooling systems (six under-floor and one ceiling application). Compare this to
the first contest in 2002, where five homes used radiant under-floor heating.
Several homes used geothermal or ground-source heat
pump systems to heat and cool the houses, although geothermal had to be
simulated since teams couldn’t drill 500-foot holes in the National Mall
Each team is challenged to design, build and
operate the most attractive and efficient solar-powered house. The overall
winner of this year’s contest was Team Germany from Darmstadt, Germany - the
team’s second victory after winning the 2007 competition. The University of
Illinois took second place and Team California (Santa Clara University and
California College of the Arts) took third place.
Visitor Clara Duffy
touches a passive-heating water wall made of recycled plastic water bottles in
the University of Arizona's solar-powered house during the U.S. Department of
Energy Solar Decathlon on the National Mall in Washington, D.C., Oct. 17, 2009.
(Credit: Stefano Paltera/U.S. Department of Energy Solar Decathlon.)
You don’t heat too much about radiant cooling, but Team
California (also winner of the Architecture contest) decided to incorporate it
in its Refract House. The team used a solar thermal absorption chiller to
supply the radiant cooling panels; waste heat from the chiller preheats water
for the solar hot water system.
Radiant in-ceiling water pipes for
heating and cooling are part of the University of Puerto Rico’s house. The
system is designed to operate at slightly cooler than the ambient temp to avoid
The University of Minnesota team’s house
uses solar hot water for domestic water and radiant under-floor heat, but the
solar water heating system is used in the summer to recharge a desiccant system
that efficiently pulls moisture out of the home’s air to maintain humidity and
comfort levels. Iowa State’s Interlock House had a similar system.
Rainwater collection was integrated into
Team Boston’s (Boston Architectural College and Tufts University) Curio.House,
the University of Wisconsin-Milwaukee’s Meltwater house and the University of
Puerto Rico’s home.
Virginia Tech incorporated a rainwater
collection system and a grey water filtering system. The roof is sloped to
collect rainwater that is filtered for potable water, while grey water is goes
through a series of bio-filters in the surrounding landscape where it is
cleaned for nonpotable use.
The University of Illinois at
Urbana-Champaign won the hot water contest with its hot water system heat
exchanger. The “shower tests” requires systems to deliver 15 gallons of hot
water in 10 minutes or less.
Penn State installed water bags to
provide thermal mass, absorbing heat through the day and releasing it at night.
The bags were not filled until the house got to its site to reduce fuel use.
The “water wall” at the University of
Arizona’s SEED[pod] home helps reduce heating and cooling needs. One of the
passive energy and comfort strategies used in the house, the vacuum-formed
clear plastic water wall acts as a “heat sink” by deterring heat from entering
the house during the day and releasing it slowly after the sun goes down.
It sure is an innovative way to keep plastic water bottles
out of the landfill…