1. The document evaluates future refrigerant options for air conditioners based on their global warming impact, energy efficiency, flammability, toxicity, and cost.
2. It finds that R32 has a much lower direct global warming effect than R22 or R410A, and its impact could be further lowered through design modifications. It also has equivalent or better energy efficiency than alternatives.
3. While R290 (propane) poses flammability risks, the document argues for early adoption of technologies available now to significantly reduce future greenhouse gas emissions from refrigerants.