Since Japan has set a goal to reduce greenhouse gas emissions by 26% in 2030 compared to 2013, the Ministry of the Environment in cooperation with relevant ministries and various enterprises, organizations and local governments, is now promoting the national campaign called “COOL CHOICE” to encourage people to make “cool” choices in every aspect of life. This “COOL CHOICE Design Workshop” was conducted to identify effective and practical alternatives for the way of choosing low-carbon “products,” “services” and “lifestyle,” which serve as global warming countermeasures. This workshop involved cooperation with industry and government. It was held at the University of Tokyo on July 15th and 29th, 2017. On the first day of the schedule, GCL students, people from industry and government got together and first listened to two guest lectures. After the lectures, participants were randomly divided into five groups and did two activities: “Brain Writing” and “Outback,” which were used to generate a lot of ideas for “COOL CHOICE.” As the last activity for the first day, each group made a short presentation to summarize their outcomes of each. On the second day, the five groups of GCL students first made quick presentations for the people from industry and government to get feedback on the ideas generated on the first day, which students had developed during the subsequent two weeks. Each group worked with members of industry and government to develop their ideas for the final presentation. At the end of the schedule, an idea competition was held, and five ideas were presented. Based on this workshop, it was decided that the two best ideas would appear in an issue of a business magazine, Toyo Keizai, in 2018.