Changes in Energy Star Portfolio Manger Effect Weatherized Site EUI
Although the targets, reporting dates, and what can be excluded from Building Performance Standard (BPS) jurisdictions can vary, there is one constant and universal consistency: all BPS jurisdictions require that building energy (and sometimes water) data be entered into EnergyStar Portfolio Manager (ESPM). ESPM has been providing utility performance benchmarks for Commercial Real Estate since 1999 and is the largest repository of building utility data in the nation. The EnergyStar Logo is the most widely recognized symbol of efficiency on the market today. This is why any updates to the system are significant to all users (jurisdictions, property owners, lenders, and programs.)
But big changes are coming in 2025 that Multifamily needs to be aware of. As of January, Energy Star Portfolio Manager will update how weather normalization is calculated. First, the number of available weather stations in Portfolio Manager will significantly increase, allowing for more precise mapping of buildings to the most relevant weather data. Second, ESPM will now use a 15-year weather average for normalization instead of the older 30-year average, reflecting recent climate changes. These two changes could have potentially a substantial impact on the performance of buildings from an EnergyStar Certification perspective as well as impact compliance with BPS.
Many jurisdictions use weatherized site energy use intensity (EUI) as a metric for their performance target. A "weatherized site EUI" refers to a building's (EUI) that has been adjusted to account for the impact of local weather conditions, essentially showing how much energy a building would have used under average climatic conditions. ESPM’s weatherized site EUI is extensively used for this target. In many respects, the weatherized site EUI is a more equitable measure of performance against targets because it adjusts for significant weather events, such as severe cold or heat events. Without using a weatherized EUI target the risk of non-compliance can increase due to Climate events which a building owner cannot control. The downside will potentially be experienced by those buildings in smaller, milder microclimate zones whose performance was artificially diluted by weather from other more extreme climate zones. For example, in the summer in San Francisco California, temperatures can be ten degrees cooler than the City of Oakland which is less than 12 miles away. When thinking of days you might require air conditioning, Oakland will have more days than San Francisco. If both cities previously were included in the same climate zone (which from a distance perspective appears reasonable), the buildings in San Francisco might have a lower weatherized site EUI than an Oakland property. With the increase in the number of weather stations used, there will be more accuracy in the actual number of heating days and cooling days normalizing the site EUI.
The potential effect of the changes means that the weatherized EUI will be more accurate for buildings, but that could mean a change in the building performance scores while the jurisdiction’s targets remain the same. Owners and operators whose performance scores were close to targets should pay close attention to see if their EUI scores change, which might put them into or out of compliance with the jurisdictional targets. Additionally, the changes in weather normalization are expected to change EnergyStar scores and ability to certify. There are some exceptions for specific jurisdictions related to EnergyStar certified properties which may not be available to buildings that previously scored high enough to qualify without retrofit or recommissioning. Any modeling of an efficiency upgrade based on the historical weatherized site EUI in ESPM could also be affected; this means that CapEx projects that have been approved to comply with future BPS targets may not see the impact to the property’s EUI that was anticipated.
It is not all unwelcome news. With the changes in weatherization, we will now have a clearer picture of the performance of our buildings and really understand how to improve them for future performance. ROI calculations will be more accurate with these changes to ESPM; we will just have to embrace how these changes will affect our immediate compliance with BPS. Therefore, in 2025 it will be critical to assess any changes in weatherized EUI for a property and be prepared to pivot as the new refined scores are available to us.
At GreenT Climate Software, we help owners and operators of Multifamily properties navigate the complexities of regulation, the changes to BPS and ESPM, and provide guidance to the correct pathway for compliance.
