ENERGY STAR Score Explained: What It Means and How to Improve It
We talk a lot on the EnergyWatch blog about ENERGY STAR benchmarking, guidelines, and scores. But what, exactly, does an ENERGY STAR score mean, how is it calculated, and how can you raise the ENERGY STAR score of your building, facility, or manufacturing plant? We’ll answer all those questions and more in this article.
What Your ENERGY STAR Score Means
The ENERGY STAR score provides a comprehensive snapshot of your building’s energy performance. It assesses the building’s physical assets, operations, and occupant behavior in a quick and easy-to-understand number. Your ENERGY STAR score is on a scale of 1 – 100. The score is meant to be a screening tool that helps you assess your building’s efficiency performance. If you own and/or manage more than one building, the ENERGY STAR score will help you determine which buildings in your portfolio you could improve or submit for recognition. A score of 50 is the median, so if your building has a score lower than 50, you know it’s performing worse than 50 percent of similar buildings nationwide. Meanwhile, while a score over 50 means just the opposite – your building is performing better than 50 percent of its peers. Finally, a score of 75 or higher means your building is a top performer and may be eligible for ENERGY STAR certification.
What Your ENERGY STAR Score Doesn’t Tell You
The 1 – 100 ENERGY STAR score cannot explain why your building is performing in a certain way or tell you how to change your building’s performance for the better.
The score does:
- Evaluate your actual billed energy data
- Adjust for business activities (e.g. hours the facility is in use, number of workers, and the climate)
- Compare your building to similar buildings nationwide
- Tell you your building’s level of energy performance
The score doesn’t:
- Add up the energy used by each piece of equipment in your building
- Explain why your building is performing a certain way, whether it be good or bad
- Credit specific technologies with an aspect of performance
All About the National Survey Data
To determine your score, ENERGY STAR compares your building(s) to other buildings across the nation that are used for the same primary purpose. So, where exactly does ENERGY STAR get this peer group from?
Every four years, the U.S. Department of Energy’s Energy Information Administration (EIA) runs a national survey to acquire data on building characteristics and energy use from thousands of buildings across the United States. This Commercial Building Energy Consumption Survey (CBECS) is the sole source of national-level data on the characteristics and energy use of commercial buildings. For most U.S. property types, your building’s peer group for comparison will be buildings similar to yours, that are in the CBECS survey.
If you have buildings in Canada, your building’s peer group is based on a similar data source, the Survey on Commercial and Institutional Energy Use (SCIEU). This survey is commissioned by NRCan and carried out by Statistics Canada. NRCan applies the same filtering strategy as the EIA (e.g. building type, program, data limitation, and analytical filters).
Finally, for some property types like hospitals or nursing homes, industry associations conduct nationally representative surveys to gather a sizeable data sample.
How Is Your Score Calculated?
First, you enter basic information about your building (e.g. size, location, number of occupants, number of PCs, etc.) into the system. Then, the score’s algorithm will estimate how much energy your building would use if it were performing at its best, at its worst, and other levels in between. To estimate how much energy your building would use at each performance level, statistical analyses is conducted on the survey data. For each type of building for which there is an ENERGY STAR score, you know that:
- The quality and quantity of the building’s data will support an ENERGY STAR score
- There is a statistical regression model that correlates the energy data to the property use details to identify the key drivers of energy use
- The model has been tested against thousands of buildings in Portfolio Manager
Finally, the algorithm compares the actual energy data you entered to these estimates to determine where your building ranks relative to its peers. All calculations are based on source energy and account for weather variations.
The Nitty Gritty Details
For an in-depth look at the methodologies, analyses, and calculations used in Portfolio Manager (i.e. your ENERGY STAR score!), you can refer to the Portfolio Manager Technical Reference series:
- Portfolio Manager Technical Reference: ENERGY STAR Score has more information on how your 1-100 ENERGY STAR score is calculated.
- Portfolio Manager Technical Reference: Climate and Weather provides a detailed explanation of how Portfolio Manager corrects for the climate and weather fluctuations in your region.
- Portfolio Manager Technical Reference: Thermal Conversion Factors shows you the calculations used to convert your entered energy data into standard units (kBtu or GJ).
- The difference between source and site source energy explains why source energy is used for national median benchmarks and your ENERGY STAR score.
- ENERGY STAR score details by property type has insight on the specific data analysis and methodology used to calculate the ENERGY STAR score for each type of property.
Specific ENERGY STAR Score Details for U.S. Buildings
For more information about the way your ENERGY STAR score is calculated, find the property type that best matches your own in the list:
- Data center
- Data center estimates
- Hospital (general medical and surgical)
- K-12 school
- Medical office
- Multifamily housing
- Office (covers office, bank branch, financial office, and courthouse)
- Residence hall/ dormitory
- Retail store (covers retail and wholesale club/supercenter)
- Senior care community
- Supermarket/grocery store
- Swimming pool
- Warehouse (covers distribution center, non-refrigerated warehouse, and refrigerated warehouse)
- Wastewater treatment plant
- Worship facility
How Can You Boost Your ENERGY STAR Score?
As we mentioned above, your ENERGY STAR score won’t tell you what is behind your building’s performance or how to fix it. Luckily, energy management software like EnergyWatch’s watchwire can do both of those things. Watchwire offers real-time and interval data monitoring, which helps you pinpoint exactly when and where your operational inefficiencies are occurring. Once you know how your building is losing energy, you can take steps to fix it. This will make your building more efficient, thus lifting your ENERGY STAR score. Additionally, watchwire offers measurement and verification (M&V) for efficiency projects, so you’ll know for sure if the efficiency and sustainability fixes you instituted are working. Finally, watchwire uses visualized invoice data to identify utility account level and aggregate property level trends in consumption, demand, and costs. This data is used to benchmark your properties against each other to prioritize sustainability and efficiency opportunities with the quickest payback and largest impact (based on KPIs such as kWh/ft2, watts/ft2, etc.).
To learn more about watchwire, click here to download the Watchwire Solution Brief. For more information on measuring and verifying efficiency projects, click here to watch our webinar, How to Measure and Verify Efficiency Projects.