Halfway through installing a green roof on Wednesday night, May 2, Corrie Zoll stopped to take a slug from a bottle of Guinness. It wasn’t that he was tired out. Just three minutes into the demonstration, he was illustrating for the near-sellout crowd at the Southern Theater how easy it is to install a green roof and how such technology can help the environment by cooling buildings through both shade and “evapotranspiration.”

Which is where the beer comes in.

Because plants move vapor from their roots and release it through their leaves, a green roof on a two-car garage can “sweat” five gallons of water on a hot day  — enough to fill 57 bottles of Ireland’s finest.

Zoll and RoofBloom’s Chris Wegsheid were among 13 groups presenting ideas at the first edition of Solutions Twin Cities, a networking event/show-and-tell session/progressive social, organized by Colin Kloecker, a blogger at Worldchanging Twin Cities who works at Cermak Rhoades Architects, and Troy Gallas, a member of Architecture for Humanity – Minnesota. Intended to showcase change-oriented projects in design, ecology, community development, and culture, Solutions takes its format from pecha kucha, a presentation format developed in Japan in which each each speaker gets 20 seconds to discuss each of 20 slides. As Worldchanging’s Eric Larson aptly wrote, it’s “no guff, no fluff, just the essence of the ideas.”

While Zoll and Wegscheid fabricated a 3 x 4-foot section of roof, others used their time to discuss “future-positive creativity” ideas ranging from alternative currency systems and sustainable communities in Kenya and Uganda to Urban Earth, a new flower shop in southwest Minneapolis that’s one of the country’s only non-food-based co-operatives. For example: