A major shift in a building’s ENERGY STAR score can quickly catch a property team’s attention. When the score changes by several points between reporting periods, the team may wonder whether equipment, operations, occupancy, or energy use has changed. Before drawing conclusions, though, it’s important to understand what may be behind the number. 

The 1–100 ENERGY STAR score measures a building’s energy performance against similar buildings nationwide. Its methodology accounts for factors such as weather and operating characteristics, including hours of operation and other property-specific variables. The score is based on energy data and information entered into ENERGY STAR Portfolio Manager. 

Start With the Energy Data 

The first step is to look beyond the score itself. Portfolio Manager provides more than 100 metrics to help property teams analyze energy use over time, including site and source energy, energy use intensity, and weather-normalized metrics. EPA also recommends comparing 12-month periods when evaluating changes in building performance. 

Start by comparing the current reporting period with the previous period and, if possible, with the same period in earlier years. Look for changes in total electricity and natural gas use, as well as consumption of any other fuels used by the property. If the score changes at the same time as a substantial shift in energy use, take a closer look at what happened in the building during that period. 

It can also be useful to examine energy use intensity (EUI), which relates energy consumption to a property’s size. Comparing EUI with total consumption can help distinguish changes driven by the amount of space being operated from changes in how efficiently that space uses energy. 

Check Weather and Operating Conditions 

Weather-normalized metrics provide another point of comparison. Portfolio Manager adjusts weather-normalized energy metrics to reflect what the building would have consumed under average weather conditions, making them useful for comparing performance across periods with different weather. 

Weather is already factored into the ENERGY STAR score, but it still matters when investigating a change. An unusually hot or cold period can affect a building’s actual energy use, particularly when heating and cooling loads are significant. 

Compare energy use with weather-normalized energy use to see whether weather may explain part of the change. For example, if consumption rose during an unusually hot summer but weather-normalized consumption stayed relatively stable, the score change may have a different explanation than it would for a building whose consumption increased even after accounting for weather. 

Review the Information in Portfolio Manager 

A score is only as useful as the information behind it. If it changes unexpectedly, review the property information in Portfolio Manager alongside the utility data. 

Confirm that the building’s gross floor area, property type, and property-use information are up to date. Review operating hours and any other variables relevant to the property type, as well as occupancy or other usage information where applicable. Portfolio Manager uses these details to normalize the building’s performance. 

Utility data should receive the same level of scrutiny. Verify that all applicable meters and fuel types are included, and that billing periods are complete and accurate. To receive a 1–100 ENERGY STAR score, EPA requires at least 12 consecutive full months of energy data covering every active meter and fuel type at the property. 

A score change after a data correction should be interpreted differently from one that follows a documented operational or equipment change. Keeping good records of meter information, utility bills, and property-use updates can make the comparison much easier. 

Look for Changes in Equipment and Building Operations 

After reviewing the data, examine what happened inside the building. Consider whether major equipment was replaced, repaired, taken offline, or operated differently during the reporting period. Changes to HVAC equipment, controls, lighting, building automation systems, or other significant energy-consuming systems may affect energy use. Maintenance records, work orders, and building automation data can help identify changes that align with the timing of a score shift. 

Operating practices can be just as important as equipment. Review changes to temperature setpoints, schedules, start-up and shutdown procedures, ventilation, after-hours requests, and other practices that affect building energy use. 

The ENERGY STAR score alone cannot identify which piece of equipment caused a change. EPA describes it as a screening tool that indicates a building’s energy performance but does not explain why the building performs at that level. Additional building-level analysis is needed to identify the cause. 

Compare the Timing 

If the score changed after commissioning a new HVAC system, changing operating hours, or a major tenant moving into the building, use that event as a useful point of comparison. Compare monthly energy consumption before and after the change instead of relying only on annual totals. 

This approach can also uncover problems that an annual score might miss. A gradual increase in energy use over several months may point to equipment degradation, control issues, or operational changes. By contrast, a sharp increase in one month may call for a different investigation, such as checking for an unusual utility bill, a billing-period issue, or a temporary operating condition. 

Consider Whether the Score Model Changed 

Sometimes a building has not changed at all, but the methodology used to calculate its score has. EPA periodically updates ENERGY STAR score models as new market data becomes available. These updates can affect scores even when a building’s energy consumption and operating conditions have remained relatively consistent. EPA notes that score calculations, including historical scores, are periodically updated to reflect the current state of commercial buildings. 

For that reason, a sudden change across the portfolio warrants a different investigation than a change affecting just one property. If several buildings of the same property type change around the same time, check whether EPA has announced an update to that property type’s ENERGY STAR score model. 

Build a Record of the Investigation 

Once you’ve identified the likely cause, document it. A simple record can include the reporting periods compared, the change in score, changes in energy use and EUI, relevant weather conditions, updates to property information, operational changes, and any equipment work completed during the period. 

This creates a useful history for future benchmarking, helping teams avoid repeatedly investigating the same issue. It also gives property managers, engineers, owners, and sustainability teams a shared record for discussing building performance. 

Thank you to our ENERGY STAR Month sponsor, Georgia Power

Learn More about Georgia Power’s Commercial Energy Efficiency Program here.

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