In today’s energy-conscious market, the ability to understand and act on building performance data is a competitive advantage. One of the most effective tools for doing so is the Energy Utilization Index (EUI)—a simple yet powerful metric that measures energy use per square foot. In this article, we’ll explain what EUI is, how to calculate it, and why it matters. We’ll walk through real-world cost impacts, explore how EUI can drive efficiency improvements across single buildings and portfolios, and show how it supports financial planning.
While the calculation is simple—total annual energy use divided by building square footage—the implications can be significant. For example, a 100,000 square-foot commercial building consuming 12.5 billion BTUs annually has an EUI of 125. Compared to the U.S. Energy Information Administration’s national average of 80.9 kBtu/ft²/year, this reflects approximately 54% higher energy use. With an annual energy cost of $500,000, the excess equates to an estimated $272,500 in avoidable expense, indicating a strong case for performance review and corrective action.
This is where EUI becomes a practical tool for decision-making. It connects energy performance directly to financial outcomes, helping leaders identify where operational dollars are being lost. A building performing well above industry average isn’t just inefficient—it’s costing more than it should. In the example above, identifying a $272,500 gap in energy costs through EUI could easily support a $150,000 efficiency project. For example, according to ENERGY STAR, a major healthcare system identified one of its hospitals with an EUI exceeding 300 kBtu/ft²/year—nearly 50% above expected levels for the same building type. With annual energy costs of over $1 million, this reflected close to $500,000 in avoidable waste. The insight led to a targeted HVAC system upgrade, costing approximately $200,000, which delivered over $200,000 in annual savings—resulting in a full return on investment in just one year.
The value of EUI becomes even clearer in multi-building portfolios. A group of five buildings averaging an EUI of 73 may appear efficient compared to the national benchmark of 80.9. But if one or two sites are operating at 101 or higher, they could be using 25% more energy than their peers. For a building with $300,000 in annual utility costs, that’s $75,000 in avoidable waste. These outliers often go unnoticed, quietly reducing portfolio performance. EUI helps managers spot and address these inefficiencies before they become long-term liabilities.
Beyond benchmarking, EUI also enables energy professionals to validate the impact of completed upgrades. As organizations roll out efficiency improvements—like advanced controls, HVAC optimization, or LED lighting—ongoing EUI tracking provides a reliable before-and-after snapshot. According to ENERGY STAR and similar benchmarking programs, buildings that actively use EUI insights typically realize 6–15% savings in the first year. To add on one national retailer used the EUI to target its least efficient stores, investing in lighting and HVAC retrofits that yielded more than $300,000 in annual savings without disrupting daily operations.
EUI is a starting point, not a final answer. While benchmarks vary by building type, a high or even low EUI can signal deeper issues—like outdated systems, poor scheduling, or underused space. Its true value lies in the questions it raises: Are systems running efficiently? Are schedules aligned with occupancy? Is this building performing as it should—or just appearing to?
In short, EUI is more than a metric—it’s a decision-making lens. It helps facility managers, CFOs, and executives identify which buildings are costing more than they should, which upgrades are worth pursuing, and how to measure success with credibility. Used correctly, it moves energy conversations from guesswork to strategy.
At Sunlight Energy Group, we specialize in making that strategy actionable. We don’t just deliver EUI metrics, we help clients turn them into meaningful savings. Whether you’re managing a single facility or an entire portfolio, EUI can help you pinpoint inefficiencies, support smart investments, and unlock capital you didn’t know you were losing. Let’s start the conversation.
