Energy efficiency is many things to many people, encompassing a wide range of technologies and approaches, from building insulation or LED lightbulbs to vehicle fuel economy or manufacturing practices. Its diverse and ubiquitous nature explains why it’s often difficult to characterize efficiency’s full impact, and why there hasn’t been a single resource that summarizes energy efficiency’s full range of benefits.  

With that in mind, the Alliance to Save Energy joined with the American Council for an Energy-Efficient Economy (ACEEE) and the Business Council for Sustainable Energy (BCSE) in December to release the Energy Efficiency Impact Report (EE Impact Report)—a first-of-its-kind publication that uses reams of data and intuitive graphics to tell the comprehensive story of energy efficiency’s impact on the U.S. economy, environment, and society. While there’s no shortage of technical reports that discuss the benefits of energy efficiency in specific sectors, the EE Impact Report instead tells a broader story of this incredible resource by characterizing 54 indicators  that highlight the breadth, depth and diversity of the energy efficiency market and explore how policies and programs have incentivized energy efficiency in a variety of sectors.

One of the main characters in the energy efficiency story is buildings: residential and commercial energy consumption primarily occurs indoors. In fact, energy consumption in homes and other residential buildings is responsible for approximately 20 percent of total primary energy use in the U.S. But even though the average U.S. resident lives in larger, better-acclimated homes with significantly more devices, the EE Impact Report shows that residential energy use per household has fallen by roughly 16 percent from 2001 to 2018.

How can we have bigger homes and plug more devices in them and still use less energy per household? Energy efficiency.

Decades of experience have taught us that energy efficiency isn’t a rabbit pulled out of a hat. Rather, it requires strong policies and proactive support from a diverse set of stakeholders. In addition to summarizing efficiency’s impact, the EE Impact Report highlights the urgent need to do more in the buildings, utility, transportation and industrial sectors. Readers can  use the Index to navigate by topic, download data and PowerPoint slides from the Resources page, or skim the footnotes in each section for even more resources.

Here are some of the most effective policies that the EE Impact Report identifies for energy efficiency in buildings.

Building Energy Codes

Building energy codes set minimum efficiency requirements for renovated or new buildings. Because the average building lasts about 100 years, stringent building energy codes lock in savings throughout a building’s lifespan. These codes have reduced covered energy use in buildings by more than 40 percent over four decades. Model building energy codes are expected to save $126 billion in energy costs and 13 quads of primary energy between 2010-2040. Moreover, a home built to the specifications of the International Energy Conservation Code of 2018 would use 40 percent less code-covered energy than if it had been built using standard practices in 1975.

Commercial Building Energy Performance Benchmarking

Benchmarking is a mechanism to gauge a building’s energy performance, helping facility managers set reasonable energy efficiency goals and assess the effectiveness of their energy savings programs. The U.S. Environmental Protection Agency (EPA) found that buildings that were consistently benchmarked reduced energy use by an average of 2.4 percent per year. Many states and municipalities have set benchmarking requirements using the EPA’s ENERGY STAR Portfolio Manager. Benchmarking through Portfolio Manager has grown to represent close to 25 percent of U.S. commercial floorspace.

Residential Home Energy Use Rating and Certification Tools

Ratings and certifications bring greater transparency to energy use. They can help homeowners better understand their utility bills and recognize opportunities for savings. There are several rating and certification tools available to help residential homeowners, builders, and property developers improve energy performance, including the Home Energy Rating System (also known as HERS ratings) and the Home Energy Score (HES rating). More than four million energy performance ratings and certifications have been performed since 2012.

Commercial Building Certifications

Building certifications help guide, demonstrate, and document efforts to construct or retrofit highly efficient buildings. Two of the most common commercial building certifications are ENERGY STAR and Leadership in Energy and Environmental Design (LEED), which have increased by nearly three- and six-fold since 2010. An ENERGY STAR certified building must perform better than at least 75 percent of similar buildings nationwide, while LEED requires the modeled design for its certified buildings to be better than a baseline building’s performance by 5 percent for new construction and 3 percent for major renovations. The first generation of certification programs often took a prescriptive approach. Now, certification programs are increasingly performance-based, which allows for flexibility in choosing strategies to meet whole-building energy performance requirements.


The above-mentioned policies and programs are just a snapshot of the array of tools available to improve energy efficiency in buildings. Despite monumental progress, there is still tremendous potential for improving energy efficiency in buildings. An influx of innovative technologies—such as smart meters, advanced controls and automation—along with greater integration of building systems are poised to drive even deeper energy savings in buildings.

The upshot of the EE Impact Report is that energy efficiency is a process, not a destination. It will continue to change along with our evolving energy system and technology landscape, creating countless new opportunities. While buildings are meant to last 100 years, their operations must continue to change and improve to optimize energy use.