DescriptionFunction-as-a-service (FaaS) platforms present a new paradigm of cloud computing that allows users to deploy and execute functions in a serverless fashion, i.e. without worrying about the management of the server or its infrastructure. Current FaaS platforms use x86-based rack servers that are expensive to maintain and consume large amounts of power. Recent work introduced MicroFaaS, a novel FaaS hardware architecture comprised of multiple ARM-based single-board computers (SBCs) that replace rack servers and provide a more energy-efficient and cost-effective solution to traditional FaaS infrastructure. The initial MicroFaaS design includes a proof-of-concept orchestration platform (OP) to allocate and invoke serverless functions on SBCs. The most recent version redesigns and optimizes MicroFaas with OpenFaaS as its OP, a popular framework for securely building and deploying serverless functions. Rigorous experimentation to evaluate MicroFaaS-on-OpenFaaS demonstrates substantial energy efficiency improvements against conventional virtualization-based cloud systems, while expanding ease of use and scalability compared to the original MicroFaas design.