With climate change a worldwide reality—the United States alone was responsible for 6,450 million metric tons of greenhouse gas emissions in 2017, up from 1990 levels—lawmakers are emphasizing the need to cut emissions from commercial buildings.

In New York City, for example, officials have passed legislation to cut emissions in large buildings by 40 percent by 2030. Los Angeles and Washington, D.C., are each implementing their own green building initiatives. And while the legislation is clear, it means that the burden has fallen to building owners to find ways to reduce emissions without sacrificing tenant comfort and building functionality or hurting investment returns. This is no easy feat.

While it is simple to find turnkey products—boilers, pumps, lighting and so on—that promise “energy efficiency,” those promises ignore the complex nature in which buildings operate. Large buildings don’t come off assembly lines—and the way a building will react to an “energy-efficient” chiller is not determined by the chiller, but by many factors unique to the specific building (e.g., building design, space utilization and control system capabilities).

For building owners seeking to reduce emissions while maintaining tenant comfort, the task involves looking holistically at buildings and gaining understanding of the systems that heat, cool and power them.  This process requires a true expert—essentially a surgeon—to conduct the evaluation and identify optimization measures.


Before conducting a procedure, a surgeon reviews the patient’s medical history, conducts a physical examination, and learns about the patient’s habits (sleep, diet, exercise, etc.). Then, the surgeon evaluates diagnostic tests, such as blood tests, MRIs, and X-rays. Having examined these factors, the physician will use their education and experience to determine the best procedure, and considers the viability of surgery.

Building owners and their property teams must emulate surgeons, and “take the pulse” of their building to understand how its systems work together to heat, cool and power it. Implementing upgrades does not automatically translate to energy reduction (much as a hip replacement does not automatically mean a patient will walk faster). The key to reducing consumption is understanding that each building is not a collection of siloed systems, but an ecosystem in which different parts interact based on governing principles of thermodynamics. And the performance of each building is impacted by its design, utilization and environmental conditions. 


Historically, building owners generally relied largely on analysis from engineers that was both limited in scope and fragmented. While these analyses were based on sound engineering, they were also largely based on limited data, and not predictive.

Imagine if doctors had a holistic tool that brought a patient’s medical history, test results and other information into a model of their unique anatomy. With a virtual model, doctors could better evaluate the outcomes associated with different types of procedures by simulating how the body would respond. Instead, surgeons have to rely on evaluations and diagnostic tests. Through an often manual process, they bring all the data together and make a judgment call based on their experience and admittedly imperfect information.

Fortunately, while somewhat complex, buildings are simpler than the human body. By leveraging the latest technology, highly accurate building representations can be created to help owners and their property teams understand how their buildings are operating and how to improve them. Similar technology has been utilized for years in manufacturing design and performance optimization for aerospace, energy and other industries.


Advances in Internet of Things devices, data science and machine learning have created a new front for evaluating building performance. The most comprehensive of these solutions are simulation models or “digital twins.”

Simply put, a digital twin is a virtual building replica. A “digital energy twin allows owners to not only understand how buildings operate in relation to design, but to predict with near-perfect accuracy how upgrades will impact building performance, energy consumption and investment returns.

A digital energy twin simulates the entire operation of a building. The twin is created by collecting inputs such as building design and utilization information, real-time operating data (zone temperatures, equipment operation and energy consumption) and weather information to paint a complete picture of the building.

Once an accurate twin is created, software can run simulations on different building upgrades (e.g., reprogramming existing systems, replacing boilers or chillers, upgrading motors) to gauge the impact on performance and energy consumption. The dynamic nature of these models lets you assess countless future scenarios, taking into account prospective changes in space utilization (density of occupancy, floor plans, plug loads, etc.) and weather. For example, if part of an office building may be converted into co-working space, a digital energy twin can calculate the impact on cooling loads, energy consumption and equipment wear and tear.

In recent years, I’ve evaluated many building control systems and energy management software platforms, but none have the potential emission-reduction powers of digital energy twins, which is why we at Bractlet began developing our own. A recent example demonstrates the power of these twins.

About a year ago, our data collection hardware was deployed in a large building in Nashville, and we built a model to identify opportunities for improving building performance. Our resulting recommendations forecasted energy savings of approximately 31 percent. These optimizations included reprogramming the building automation system to more efficiently heat and cool the building, while operating the equipment less—resulting in lower operating costs and extended equipment life.

Of course, a forecast is only as good as its accuracy. However, 16 months since our calculation, the forecasted energy savings for the implemented projects have been 99 percent accurate.

In markets like Nashville, there is no legal impetus for emission reduction. However, the high level of accuracy in digital energy twins gives building owners a tool to gauge the precise financial impact, making the business case for reducing energy use.


Similar to post-surgery evaluations (which evaluate how patients are recovering to determine if additional treatment is required), after making upgrades to a building, it’s possible for a digital energy twin to monitor the building’s performance and energy consumption to ensure the building is operating optimally and the upgrades were successful. To the extent that they weren’t, the owner risks a host of issues.

In one startling example, a large office building had installed a $500,000 “energy-efficient” chiller. Unbeknownst to the building owner, the system was installed incorrectly; instead of increasing efficiency, it was guzzling energy. With our digital energy twin, we identified the issue and worked with the property team, equipment manufacturer and contracting firm to provide corrective action.

As cities across the country ramp up efforts to combat climate change, it has become challenging for building owners with relatively limited insight into building operations to reduce building emissions. In this environment, it is imperative for building owners to partner with technology providers to better evaluate building performance, identify energy reduction opportunities and reduce operating expenses in the most holistic manner.