[Note: An adapted version of this article was published in the Fall 2016 edition of Issues in Science and Technology, the public policy journal of the U.S. National Academies of Sciences, Engineering, and Medicine.]

I fully support the promotion of new and more advanced building energy technologies as a means to improve building performance and reduce energy use and related carbon emissions (“The Potential of More Efficient Buildings”, Issues in Science and Technology, Summer 2016). However, to fully realize these aims, we cannot rely on advancements in building technology alone.

For one thing, only a fraction of a building’s total energy use is related to the efficiency of the technology within it; the remainder is a function of the operations-related management practices and the behavior of the people who use the building (although technology can be used to help in these areas, too). Furthermore, deep reductions to energy use and carbon emissions cannot be achieved by focusing only on new technology for new buildings. Existing buildings have to be contended with. It is estimated that about half of the world’s building stock in 2050 will consist of buildings that already exist today; for cities such as New York and London, the share made up by the existing building stock is even higher (75% and 80%, respectively).

What’s needed, then, is for building energy technology to complement other related policies and initiatives to reduce building-related energy use and carbon emissions. There is one solution in particular that is as promising as it is simple: data transparency. Mandatory disclosure of building performance data is a relatively new practice that requires owners of large properties, often commercial and multifamily residential buildings, to publicly disclose key environmental data, such as carbon emissions and energy and water use. Disclosure programs have been (or are in the process of being) implemented in dozens of jurisdictions across Europe, Australia, and North America, including in such cities as New York City, San Francisco, Seattle, Toronto, and Washington, DC.

Jurisdictions that have implemented mandatory benchmarking policies have reported energy savings and subsequent financial benefits in a relatively short time. Early research conducted by the US Environmental Protection Agency estimated that requiring owners to disclose their building’s energy performance alone can lead to energy savings of 7% over four years. In the first three years that New York City implemented its Local Law 84, which requires owners of large buildings to disclose energy and water performance, the median commercial building energy use intensity was reduced by approximately 10%. Building owners are also required to complete energy audits and undergo retro-commissioning every five to 10 years to help achieve these savings.

There are other environmental and financial benefits of mandatory public disclosure of building performance. It provides building owners and managers with an effective and consistent measure of their building’s performance and enables them to see how they rank compared with other similar buildings, thereby offering a benchmark for setting performance targets. In addition, utilities and service providers can use the data collected to create and tailor more effective energy conservation programs, policies, and incentives. As more energy data becomes available, it becomes easier to identify which buildings (and which building types) are underperforming. Energy conservation programs can then specifically target these buildings, making the task of improving their performance more manageable. To complement their building performance disclosure programs, some cities have created engaging and data-rich visualization and mapping tools available for free online. Notable examples include Philadelphia’s Energy Benchmarking map and New York City’s Energy & Water Performance Map. Most importantly, disclosure of building performance data allows the market to introduce mechanisms that value environmental efficiency in purchasing, leasing, and lending decisions.

Although I agree that building energy technologies are among the most important and intellectually exciting technology challenges facing the world today, I would go even one step further: some of the most intellectually exciting challenges facing the world today are provided by the built environment as a whole.