Right now, large language models (LLMs) are changing how to think about climate-smart designs. Many cities are having a tough time with climate change issues. LLMs help evaluate environmental challenges that city creators need to think about when trying to build smarter cities based on shifting climate data. This chapter dives into how AI is increasingly being used for environmental goals and explores how LLMs can back up climate-sensitive approaches in urban design. It shows how LLMs can help understand huge amounts of data on energy use, urban heat islands, and air quality for city planners fighting climate change. Also, share other ways, LLMs can be applied in urban planning, pointing out how AI might reshape city layouts to better handle climate risks. To find case studies currently using LLMs in the real world, along with our thoughts on how AI could enhance building sustainable cities moving forward.