For many years, designated historic buildings have been exempt from most energy conservation codes. However, with increased attention to the perils of climate change, some cities—including New York—are adopting strong laws on building energy use that do not have this exemption. Historic preservation laws that have not caught up, and some fire codes, may pose obstacles to the installation of rooftop solar and some other methods to reduce building energy consumption.

One of the major rationales for this longstanding exemption was the idea that older buildings are more energy efficient than new ones, and thus should not have to undertake further energy conservation measures. This rationale has been called into doubt by a study published in October by Erica Avrami, Jennifer L. Most, Anna Gasha and Shreya M. Ghoshal (Avrami study) of the Graduate School of Architecture, Planning, and Preservation of Columbia University.