This paper introduces the major state-level regulations and policies for improving energy efficiency in buildings. The purpose of the review is to discuss the challenges and issues in policy implementation and the latest trend in adopting innovative instruments. The implementation of customer efficiency programs increasingly incorporates non-price instruments to encourage participation and deep savings. States pay attention to not only code adoption and update but also compliance and evaluation.

Building energy efficiency is an important strategy for reducing greenhouse gas emissions globally. In fact, 55 countries have included building energy efficiency in their Nationally Determined Contributions (NDCs) under the Paris Agreement. This research uses building energy code implementation in six cities across different continents as case studies to assess what it may take for countries to implement the ambitions of their energy efficiency goals.