FOCAL: A First-Order Carbon Model to Assess Processor Sustainability

Sustainability in general and global warming in particular are grand societal challenges. Computer systems demand substantial materials and energy resources throughout their entire lifetime. A key question is how computer engineers and scientists can reduce the environmental impact of computing. To overcome the inherent data uncertainty, this paper proposes FOCAL, a parameterized first-order carbon model to assess processor sustainability using first principles. FOCAL's normalized carbon footprint (NCF) metric guides computer architects to holistically optimize chip area, energy and power consumption to reduce a processor's environmental footprint. We use FOCAL to analyze and categorize a broad set of archetypal processor mechanisms into strongly, weakly or less sustainable design choices, providing insight and intuition into how to reduce a processor's environmental footprint with implications to both hardware and software. A case study illustrates a pathway for designing strongly sustainable multicore processors delivering high performance while at the same time reducing their environmental footprint.