Passivhaus in the New York Times
by Lloyd Alter, Toronto 
on 12.27.08
Family in Passivhaus; Rolf Oeser for The New York Times
Elisabeth Rosenthal visits a Passive House in Germany and describes their construction:
Using ultrathick insulation and complex doors and windows, the architect engineers [sic] a home encased in an airtight shell, so that barely any heat escapes and barely any cold seeps in. That means a passive house can be warmed not only by the sun, but also by the heat from appliances and even from occupants’ bodies. And in Germany, passive houses cost only about 5 to 7 percent more to build than conventional houses.
Rosenthal concludes with a summary of some of the problems with passivhaus design:
Because a successful passive house requires the interplay of the building, the sun and the climate, architects need to be careful about site selection. Passive-house heating might not work in a shady valley in Switzerland, or on an urban street with no south-facing wall. Researchers are looking into whether the concept will work in warmer climates — where a heat exchanger could be used in reverse, to keep cool air in and warm air out.And those who want passive-house mansions may be disappointed. Compact shapes are simpler to seal, while sprawling homes are difficult to insulate and heat.
Most passive houses allow about 500 square feet per person, a comfortable though not expansive living space. Mr. Hasper said people who wanted thousands of square feet per person should look for another design.
“Anyone who feels they need that much space to live,” he said, “well, that’s a different discussion.”
New York Times
More on Passivhaus design in TreeHugger:
Denmark Debuts First Certified Passive House
The Carbon Footprint of a Renovation vs New Construction
The Third Industrial Revolution
A Passiv Haus in Urbana, Illinois
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The drawing shows the frsh air circulating through the earth for passive cooling. I believe this was tried by Ms. Klinkenberg at the E-colab passive house and found wanting. When the summer dew-point is greater than ground temp (50 deg or so) the outside air humidity condenses in the ground tube. Not desirable.
The fix requires two fresh air paths. One path draws the air from inside the house and through the ground tube for passive cooling. The second path draws fresh air from outside and bypasses the ground tube. It is probably a bit more complex than this and should be reviewed by an HVAC engineer.
Chris