In a world where “energy utilization index” has yet to become a household term, the Environmental Protection Agency’s ENERGY STAR program plays a central role in helping commercial building owners interpret benchmarking data. By normalizing for climate and occupancy, it maps opaque energy usage numbers onto a clear 1-100 scale. Commercial buildings have been using this scale since 1999, but although the EPA has gathered data on about 2.5 billion square feet of multifamily buildings, these buildings have never been eligible for an ENERGY STAR score… until now.
For the first time, ENERGY STAR scores are available for multifamily buildings with 20 or more units. This is a game changer for the residential sector, since 30% of the U.S. population lives in apartments. One in seven of those people are in the NYC area. Buildings that have submitted NYC benchmarking data should receive their score automatically, so by the time of the city’s next benchmarking report, a whole new dataset will be available for multifamily buildings. For buildings that haven’t already benchmarked using EPA’s Portfolio Manager, the agency says it takes less than half an hour to enter the required information, assuming the building has access to its energy data.
Unlike the commercial ENERGY STAR scores, the multifamily scores are based on a dataset from 322 Fannie Mae buildings across the country. Like the commercial ratings, the score doesn’t rank buildings against each other, but against a predictive model based on the dataset. The EPA claims this model predicts 92% of the variation in total source energy use based on the data users enter into Portfolio Manager, a high degree of accuracy that will help make the scores useful for owners, governments and tenants alike.
The EPA says their goal is to “convey information about energy performance in a simple metric that can be understood by all levels of the organization.” Will this work in NYC? On the plus side, the metric is based on actual data and takes into account climate, weather, and operational characteristics of the building. It’s also a whole building indicator, and so doesn’t compare any specific apartment to another one, or distinguish common areas from living areas. Overall, it will let owners compare their building’s energy performance to its national peer group—and more importantly, track how changes to the building alter its standing over time. (And as a side benefit, it will make LEED EBOM more achievable for apartment buildings, since they’ll have an easy way to submit the required energy performance results.)
On the other hand, simplification can have a downside. The score says nothing specific about the equipment or operations and maintenance in the building. It also doesn’t provide any explanation for the score—it’s simply based on observed energy use. To more fully understand energy performance, buildings will eventually need both a performance score like ENERGY STAR (which rates the building’s actual performance—like checking the mileage you’re getting from your driving) and an asset score (which is closer to EPA’s miles-per-gallon rating and looks at the building and its equipment directly and isn’t affected by occupant actions).
The first ENERGY STAR certified buildings (those that have a score of 75 and above) will be announced in November. Stay tuned to see how NYC stacks up against the rest of the country.