Denver citizens passed the Green Roof Initiative on November 7, 2017, as part of a growing worldwide trend toward greater environmental consciousness in city planning. The Initiative compels builders to install plant material or a combination of plant materials and solar energy collection on a portion of the building’s roof. Buildings over 25,000 square feet of floor area must have a minimum of 20% of their roofs covered in green material. This ratio increases in proportion with the size of the project, with a peak of 60% required for buildings over 200,000 square feet. The Initiative reaches all new construction and remodels or additions undertaken after January 1, 2018.