Building Optimization: Benchmarking
Part 3: Benchmarking and Building Performance Standards
Building Performance Standards are gaining in popularity as a tool to drive buildings to reduce their energy use and carbon emissions—without dictating specifically how they do it.
The most typical performance metric is Energy Use Intensity, EUI, which is the annual energy use per square foot, expressed as kBtu/sf/yr. Kilowatt-hours of electricity and therms of natural gas need to be converted to a common thermal unit, KBtu, or thousand British thermal units, before they can be added for total energy use. Dividing that total energy use by square feet eliminates size as a factor when comparing buildings.
What isn’t directly captured in the metric is the benchmark, the standard that indicates whether or not the building’s energy performance is good. The benchmark values must reflect the building’s activity type and duration. Is it a hospital with 24/7 operations? or an office with a 45-hour work week? We would expect these buildings to use more or less energy respectively. Local climate also plays a role.
Seattle began requiring buildings over 20,000 SF to benchmark and report their performance in 2012. This is a disclosure ordinance which simply requires measuring and reporting, but doesn’t set a standard or target for performance. It does allow buildings to see how they compare to similar buildings.
In the absence of a regulatory standard, the most common standard is the median value for that property use type. ENERGY STAR Portfolio Manager is a free and widely used platform for utility tracking. For many building use types, Portfolio Manager will calculate a Score, based on where the building’s EUI lands on a scale of 1-100, with the median being 50.
Building Performance Standards set a target for building energy performance. Washington State, and Seattle, are leaders in this trend along with other jurisdictions as shown on the map from the Institute for Market Transformation.
The State of Washington is implementing the Clean Buildings Performance Standard with targets set for a wide range of building activities. Targets are adjusted up or down based on occupied hours, and the standard varies between the two major climate zones in the state. Buildings over 50,000 SF must meet their target in the first cycle. Buildings between 20,000 and 50,000 SF must benchmark their performance and implement the energy management program requirements, but they do not need to meet their target in this first cycle.
Seattle has recently approved a Building Emissions Performance Standard. This sets a target for greenhouse gas emissions, measured as kilograms of CO2 equivalents, kgCO2e. To calculate a building’s greenhouse gas emissions intensity (GHGEI) as annual kgCO2e/sf, kBtus are converted to kgCO2e – with different conversion factors for each fuel type. This is intended to drive building electrification (switching from natural gas which has higher emissions) as well as overall energy use reduction.
Please let us know if we can help you get the required portfolio manager profiles set up and calculate your performance targets so you can plan ahead for optimizing performance and compliance reporting.
Already have your building set up for Benchmarking? Our EMP toolkit can help with the next steps in compliance.