One of 20 solar-powered homes on display at the Mall in Washington D.C. This one is from the University of Kentucky. Credit: Mike Miskelly

The Solar Decathlon judges these houses in, of course, ten categories.

• Architecture — 100 points
• Market Viability — 100 points
• Engineering — 100 points
• Lighting Design — 75 points
• Communications — 75 points
• Comfort Zone — 100 points
• Hot Water — 100 points
• Appliances — 100 points
• Home Entertainment — 100 points
• Net Metering — 150 points

There are some interesting differences this year, compared to the last contest in 2007. Instead of charging a plug-in hybrid vehicle, as they did in 2007, teams now have to power a home entertainment system. The sponsors of the contest realized that electronic devices, like TVs, make up an ever-bigger share of a typical home’s electricity draw. That’s happening right now, while a plug hybrid car in most every driveway or garage is a thing of the future. A second new feature is that today’s solar houses are connected to the grid. The category “net metering” was not in the last contest. Teams earn points by sending more energy, created by sunlight, to the grid than they use from the grid. The ultimate goal for those of us the home performance field is that all homes become “net-zero” energy homes, or “net-positive,” meaning that the produce as much or more than the grid supplies them over the course of a year. A big problem with solar energy, as well as another renewable source, wind, is that power is created intermittently. Energy storage is necessary, and it is often expensive and not very efficient. With net-zero energy homes, the grid itself provides the storage capacity. When I lived in a Catholic religious community (Holy Cross Priests), the economics of community life were simple—take what you need and give what you can. Same for a net-zero energy house.

I wanted to take a look at the Team Germany (Technische Universität Darmstadt) home, the winners in 2007, but the house was in the process of being judged. Judges don’t announce when they will be visiting a house and which category they will be judging. Teams must keep, for example, the shower water in their solar homes at a precise temperature and flow rate all during the contest. No one knows when a judge will come to the door with a thermometer and flow gauge.

We walked by every house, and stopped at two—with the smallest lines snaking there way out front. (The Solar Decathlon expected as many as 250,000 visitors this year—looks like they made it.) We took a tour of the Iowa State and the University of Kentucky homes. I was partial to the simplicity and the day-lighting scheme of the Iowa house, which made use of simple pine siding and clerestory windows. Mike was more impressed with the Kentucky house, which had some pretty nifty fold up furniture and other creative uses of space. A member of the Kentucky team told us they were inspired by Shaker furniture. The house had wooden chairs, designed in Kentucky and made in Italy, that folded up to be hung on the walls, with decorative features that makes them pleasing to the eye. The Iowa house was made specifically with an older couple in mind. It has a simple layout and it is easy to move around in. Both the Iowa and Kentucky houses had big open showers in the bathrooms, with tiled floors and drainage. Energy efficiency and luxurious (though low-flow) showers can go hand in hand!

As of this writing (Wednesday), Team California, (Santa Clara University and California College of the Arts) is in the lead, with Illinois (University of Illinois at Urbana-Champaign) in second, Team Germany in third, and Team Ontario/BC (University of Waterloo, Ryerson University, and Simon Fraser University) in fourth. The categories of Net Metering, Engineering, and Lighting Design have yet to be judged.

Updates soon!

How much air is your house leaking? Are you unknowingly slurping in dirty air from your garage and attic? Perhaps a blower door test can help you find out.

"I went to the ServiceMagic Web site that I learned about editing a Home Energy article," says Tom. "Within less than a minute after I entered some basic information about my house and what I was looking for in the way of an energy audit, the phone rang." It was Sustainable Spaces, a home performance contractor located in San Francisco. Tom made an appointment for his audit for the next week. "They were offering a 'Stimulus Special' for $395."

The house Tom shares with his partner Dmitri was built in 1907. "The home has never been remodeled," says Tom. "We recently had the furnace replaced with a hot water radiant system. We have been careful to keep to the original features of the home, so we got our radiators from buildings built around the same time that used to be part of the heating systems in buildings at Fort Baker." They also installed a renewable energy source. "We installed photovoltaic (PV) panels on our roof, but we should have had the audit first to show us how to use less energy and save on the PV.  Our annual true-up statement says we owe $75 for electricity, but I want to get that down to $0!"

Rob Mitchell, an experienced contractor who knows a lot about Bay Area houses, came with two younger men for an audit of Tom and Dmitri's 102-year-old home. The crew closed all the exterior doors and windows, installed a "blower door" in the main doorframe, and depressurized the house. Immediately, dust and insulation particles began to pour through the "pocket doors" from the attic. After taking some measurements to get a general sense of how leaky the house is, and blocking some of the major air leaks, the crew from Sustainable Spaces then pressurized the house. "We walked around the house with a liquid pencil, which showed there is airflow around switch plates, gaps in the baseboard where the home is connected to the outside, and the cabinet in our kitchen where there used to be 'torpedo tubes,' which used to hold hot water heated by the wood stove, and other places" says Tom.

So the old house has some problems with air leakage, which means heating energy being lost to the outside. The crew also found out that the humidity in the kitchen was 20% higher than that on the outside of the house. "We both took showers that morning, and I had a cup of hot tea," says Tom. That was enough to keep the humidity high a few hours later.

Since the home has no mechanical ventilation, moisture build up could lead to mold growth on surfaces in the living spaces, or-even worse because it is hidden-within the walls. Mold can degrade building materials and create poor indoor air quality. Tom has allergies and a moldy house could make it difficult for him to breathe. Since Tom is living in the mild climate of the Bay Area, where we can open windows and get fresh air other ways in our leaky houses, the moisture may not hang around long enough to be a problem. If he lived in a cold climate such as Minnesota's, or a hot-humid climate such as Atlanta's, fixing the air leaks in his house without adding mechanical ventilation could create a "sick house", meaning one with poor indoor air quality due to mold.

"We won't get the report until next week," says Tom. The report will include specific numbers for air leakage from the house to the outside-or in this case between the living spaces and the attic and basement. Too much air flow means lost energy and too little means a sick house. The report will also give a range of measures that will make Tom and Dmitri's house healthier and more energy efficient. "We'll decide what measures we want done when we get the report. We made our heating system more efficient with the radiant system that heats the living spaces and provides us with hot water. We use half the gas now to heat water than we did before. So spending a lot more on fixing the building envelope doesn't make so much sense to us right now. We'll probably fix the big leaks by air sealing around the attic. And we may insulate under the floor between the living spaces and the basement."

"I wanted to have our house audited mostly because I'm curious," says Tom. "And we want to save energy." But from now on when Tom talks about home performance, and the importance of healthy and efficient homes, it will take on a whole new dimension-the homeowner's perspective.

Artist concept of the Phoenix lander,
sleeping under the darkening polar skies of Martian autumn.

But that was last May, and Phoenix has operated near Mars' northern polar ice cap going on six months now! The mission has continued a couple months longer than originally planned, giving Phoenix more time to dig in the icy soil, bake scooped up samples to detect what chemicals sublimate, track the polar weather day and night, and look to the skies with its various instruments.

Phoenix sent back some very interesting news. Indeed, it had landed on what turned out to be dust-coated water ice; ice that contains chemicals like calcite and perchlorate– the former of which may indicate past liquid water on Mars, the latter of which, however, is generally toxic, and may complicate arguments for life, past or present, on Mars.

One of the more "fanciful" detections by Phoenix was falling snow: two or three miles above, Phoenix detected ice crystals falling from clouds– albeit flakes that never made it to the ground, instead evaporating like Earthly virga back into the atmosphere.

But Phoenix’s mission has a built-in conclusion (unlike the seemingly perpetual Energizer Bunnies exploring the Martian tropics, aka the Mars Exploration Rovers). Phoenix landed at 68 degrees north latitude– that’s equivalent on Earth to the north coast of Alaska, Norway, or south central Greenland– prior to Martian northern summer solstice (which was June 25). As with Earthly summertime, the polar days were unending, the Sun above the horizon 24 hours a day (yes, Mars' day is about 24 hours long, just as on Earth). This provided Phoenix with its electrical power, generated by photovoltaic panels.

But now the Sun is dipping below the horizon several hours a day as the Martian northern hemisphere slides in the direction of autumnal equinox (December 26, 2008), at which time the Sun will spend half the time below the horizon, the other half never rising very high. Already, Phoenix's solar panels are generating considerably less power than in the heyday of its mission. A dust storm, filling the air and blocking some of the already weak sunlight, has also cut available power to the lander for a time in October.

The diminishing conditions also caused Phoenix to put itself into an automatic "sleep" mode in late October, waking up for only a short time each day, when solar energy was at a peak. To give a flavor of the temperatures Phoenix is enduring, on Sol 151 (the 151^st Martian day since landing-October 27^th, Earth time), the daily high reached a balmy 50.8 degrees F-negative 50.8 that is! The night time low hit -128 degrees F… .

With every day possibly being the last we hear from Phoenix, scientists are collecting as much data as possible, mostly focusing on meteorological conditions. Reporting from the Martian polar ice cap, as the icy darkness of winter begins to settle in, this is Phoenix Lander, signing off….

Proposition 7 is one of the green propositions – in more ways than one.

The amount of cash that's being spent on this so-called Big Solar initiative is prodigious. It is one of the most expensive measures on the ballot. On one side you have a little more than $5 million to pass the proposition, all from Peter Sperling, the son of the man who created the online college, The University of Phoenix. And on the other side, three utility companies have pitched in well over $27 million to defeat it.

Interestingly, the companies that stand to profit from this initiative – the many small companies that make up most of the solar and wind energy industry – are actually against the bill.

PG&E and Southern California Edison are the two biggest donors, chipping in more than $13 million apiece. To see a list of spenders, for and against proposition 7, click here.

For more on the debate, check out this discussion from KQED's Forum.

Listen to the Big Solar on the Ballot radio report online.

Blower door equipment is used to measure a home's
air leaks. A blower door test is part of the evaluation for
determining a home's HERS Index.
Photo by: D&R International

Remember the day when most men knew the horsepower of their muscle cars? Now most of us are concerned about miles per gallon. But what can we use to bring prestige to our houses? It used to be that a large square footage gave us bragging rights. But if all goes according to the plan of the Residential Energy Services Network (RESNET), the talk around the water cooler will be "What's your house's HERS score?"

Home energy ratings have been around since 1981. The idea began in the mortgage industry to credit the energy efficiency of homes towards the home mortgage. An energy efficient home means that the homeowner is spending less each month on electricity and natural gas and therefore has more to spend on the mortgage. RESNET has been developing the Home Energy Rating System (HERS) since 1981. In the beginning, it was the higher the HERS score the better. But because of the more widespread introduction of renewable energy systems, such as photovoltaics (PV) and solar hot water systems, into homes, and the ability of many houses today to produce as much electricity and/or hot water as they need over the course of a year-these are called net zero-energy houses-a HERS Index of "0″ is the goal. A HERS score of 85 means that a new home meets Energy Star standards. A HERS score of 150 means you're living with an Energy Hog. The typical existing home in the United States has a HERS Index of 130.

HERS raters look at a home's heating and cooling efficiency, insulation levels, appliance and lighting energy use, window efficiency, a home's solar orientation, and other factors that are tailored to the home's climate region, and use computer software to calculate a HERS index.

Some readers my be asking, "Why should I care?" You should care because the HERS score is becoming the standard du jour for homebuilders. If you want a bigger, energy efficiency mortgage, you'll need a HERS rater to measure the efficiency of the home you want to buy and to tell you what retrofits you need to do to qualify. If you are a builder and want to catch the "green wave" by earning an Energy Star rating for the new homes you are selling, you've got to get those homes rated by a certified HERS rater.

Many states have Energy Efficiency Portfolio Standards and Energy Efficiency Credit trading, and many more will in the future as we move towards national standards for meeting greenhouse gas emissions goals. The HERS Index is in place to serve the need for a third-party verifier of energy efficiency improvements.

Want energy efficiency tax credits for your new home? Better find a RESNET-certified rater. Moving to Canada? The Canadian RESNET, or CRESNET, is in the process of accepting the U.S. standards. I don't know the HERS Index of my home, but we did recently have some air sealing and insulation work done-but not quite to Energy Star standards. My guess is we'd score about 100. What's your HERS score?

Illustration of a blast of solar wind impacting
Earth's protective magnetic field. Credit: NASA

Did you know that the Sun also has an atmosphere, and that the Earth is inside it? In fact, the Sun's envelope of gases extends well beyond the orbit of Pluto, out to the regions of the solar system where the 3-decade-old Voyager spacecraft are only now reaching.

"Space weather" refers to the conditions in space caused by the outflow of electrically charged gases (plasma) coming from the Sun—what we call the "solar wind." The term "space weather" may conjure images of cosmic tornadoes, astral lightning bursts, and some Star Trek version of a galactic hurricane– but actual space weather is nothing so Earthly and familiar.

First of all, the "air" in space is nothing like the atmosphere we draw our breath from. Earth air, at the surface, is made of nitrogen, oxygen, argon, carbon dioxide, water vapor, and other trace elements, and is relatively dense. "Space air" is mostly hydrogen– ionized hydrogen at that (meaning stripped of its electrons and so electrically charged; the separated electrons are also blowing along in the solar wind).

Second, the gases of the solar wind are extremely rarified. Despite the talk of a solar atmosphere, solar wind, and space weather, space within the solar system is still almost a complete vacuum. At Earth's distance from the Sun, the average density of the solar wind is somewhere between 6 and 9 atoms (mostly hydrogen) per cubic centimeter. If you spread out the gas contained in an ordinary party balloon to this same thinness, it would fill a volume of space over 10 miles across!

Third, the solar wind, for all its sparseness, blows fast! Depending on conditions of space weather, the flow of solar wind past the Earth can speed along anywhere from 200 to 900 kilometers per second! Earth's fastest winds slug along at only a few hundred kilometers per HOUR.

So how does space weather—the changing conditions of the solar wind—affect us on Earth? How might you, personally, have experienced, directly or indirectly, the effects of the Sun's gentle breeze?

The most familiar phenomenon caused by space weather is Earth's beautiful auroras —the northern and southern lights. Interactions between the solar wind and Earth's magnetic field and electrically charged particles trapped in it excite atoms in the upper atmosphere to emit light. And it's not just a softly glowing night light: the most powerful auroras can generate up to a trillion Watts of power!

Solar wind "storms" can not only produce more active auroras, but can cause fluctuations in Earth's magnetic field whose effects can be felt on the ground. These "geomagnetic storms" usually pass unnoticed, perhaps causing a tiny change in the direction that compass needles point– but have also been known to overload electrical power grids and cause blackouts.

In the space around Earth, solar storms have been known to damage or disable satellites, and can put unprotected astronauts at risk. Space walks on the International Space Station are scheduled for times when space weather is – so to speak -"sunny and calm."

Thinking about space weather on Earth might seem like worrying over Atlantic hurricanes here in the Bay Area—but with more and more human activity taking place beyond the confines of our atmosphere, this is a very real and vital concern, and is taken very seriously.

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.

7/23/08 UPDATE: The contentious battle between solar energy and redwood trees has come to an end. Governor Arnold Schwarzenegger has signed a bill into law that guarantees if California property owners plant a tree before a neighbor installs solar panels the neighbor can't require the tree to be chopped down, or trimmed, if it is shading their solar panels. Check out this article in the San Jose Mercury News.

You may listen to the "The Right to Sunlight: Solar vs. Redwood Trees" Radio report online, as well as find additional links and resources.