Chasing Perfection: Energy Performance in the Nation’s Aging vs. New Housing Stock

Executive Summary

The primary focus of energy codes is improving the efficiency of new homes and reducing natural gas use in new construction projects. Yet, older homes, which make up the majority of the housing stock and tend to be far less efficient, receive far less attention in these policy discussions.

Residential natural gas consumption rose until the early 1970s but has remained relatively flat for more than five decades, even as housing and population have grown substantially. Over the same period, natural gas use has increased significantly in power generation and industrial sectors; the residential sector’s share of total U.S. natural gas use has fallen considerably.

To examine housing efficiency trends, the Housing Affordability Institute asked an energy code and engineering consultant to compare model homes built today to those built 30 years ago across five climate zones. The analysis also reviewed the age distribution of housing in each market, noting the efficiency in relation to the share of single-family housing by age.

Across all five regions, the largest share of housing consists of older homes, which are also the least efficient. As a result, much of the potential for efficiency improvements lies within the existing housing stock rather than new construction.

Current policy approaches constrain outcomes by focusing heavily on increasing efficiency requirements for new homes. While these standards continue to improve building performance, they affect only a small portion of total housing. Older homes, which dominate the housing stock and present the greatest potential for energy savings, see far fewer improvements at scale.

Because residential natural gas use has remained stable for decades, focusing policy primarily on new homes may limit broader progress in reducing overall consumption and improving efficiency across the housing sector.