A series of Advanced Energy Retrofit Guides for “Practical Ways to Improve Energy Performance” were developed in cooperation with the US DOE (United States Department of Energy) and PNNL (Pacific Northwest National Laboratory) in 2011. These guides were aimed at improvements to existing Retail and Office buildings which could improve their energy efficiency. Cool roofs were not recommended for all locations. “This measure is likely more cost-effective in the hot and humid climate zone, which has a long cooling season, than in the very cold climate zone, for example. For buildings located in warm climates, this measure is worth consideration.”