Pretty balanced take on a newish concept. All was not rosey, portrayed the negatives as well as the positives. All manner of public perceptions and understandings, the high costs, the failures in materials, the shipping of sustainable materials from the other side of the world. Hmmm. ( )

Who holds the key to turning down the global thermostat? Architects. If that answer surprises you, let the writers and stars of King Corn connect the dots with this inspiring film that argues for widespread adoption of green building practices, while still presenting the contradictions and quandaries. Estimates suggest that buildings and their construction account for 40 to 50% of the greenhouse gas emissions and energy consumed annually. Through design, architects could cut that number in half, and one brave development in the heart of South Boston answers the call: The Macallen Boston building saves 600,000 gallons of water, uses 30% less energy, and employs earth-saving building materials like highly compressed straw. The film achieves natural tension by following the struggle to achieve LEED gold status, the highest level of green building accreditation, and revels in the greening of southern Boston's construction workers, born skeptics who rise to the occasion. The fluid editing and zippy time-lapse photography stand out — as well as the hip soundtrack by Force Theory, who did scores for Favela Rising and Manda Bala. (MF)