We often receive interest from individuals looking for a "Net Zero Energy" home - one whose NET energy bill is or approaches zero.  By providing the most advanced structurally insulated panels on the market today our panels are perfect for this application.  We recently reviewed with a potential customer in Canada that our 6.5" wall panels would perform at approximately R48 for him - about as close to a "perfect" thermal envelope as you're going to get in 6.5".  Passive houses - ones that by passive design simply minimize (and in some cases negate) heating and cooling expenses - are of a similar nature.  The New York Times published an article this past weekend focusing on ground zero for passive house research - the Passivhaus Institut in Darmstadt, Germany.  Here are some great excerpts from the article....

The concept of the passive house, pioneered in this city of 140,000 outside Frankfurt, approaches the challenge from a different angle. Using ultrathick insulation and complex doors and windows, the architect engineers 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.

....Decades ago, attempts at creating sealed solar-heated homes failed, because of stagnant air and mold. But new passive houses use an ingenious central ventilation system. The warm air going out passes side by side with clean, cold air coming in, exchanging heat with 90 percent efficiency.

....In Germany the added construction costs of passive houses are modest and, because of their growing popularity and an ever larger array of attractive off-the-shelf components, are shrinking.

But the sophisticated windows and heat-exchange ventilation systems needed to make passive houses work properly are not readily available in the United States. So the construction of passive houses in the United States, at least initially, is likely to entail a higher price differential.

see the full article here

There's also a whole wealth of information and resources on the Wikipedia page here