Workers install insulation ice box structure during the Ice Box Challenge in Vancouver, Canada, July 27, 2017. The Ice Box Challenge is a public experiment to demonstrate the benefits of super energy-efficient buildings under the passive house construction standard. Two small house-like boxes built with passive house standard and local building code specifications sitting side-by-side under open area for 18 days with a one-tonne block of ice encased in order to testify the new zero emission building standard. (Xinhua/Liang sen)
