Gridoptimal Metrics Offer Guidance on Optimizing Building-Grid Interaction

Measurement and metrics are at the core of nearly all business activity today. Those in the buildings and energy efficiency field are accustomed to some standard metrics: Energy Use Intensity (EUI), percent better than code, cost per square foot, and more recently tons of CO2 emitted. Achievements in energy efficiency are often measured using these standardized metrics. But consistent, clear metrics have been lacking for one increasingly critical area: building-grid interactions. New Buildings Institute (NBI), the U.S. Green Building Council (USGBC), and other partners have been working to define the measures that make a building “grid-friendly” under the GridOptimal™ Buildings Initiative.

As more renewable energy resources such as solar and wind come online, whether on buildings or at the bulk grid scale, electricity grid management strategies must evolve. The grid was built for one-way energy flows from large centralized power plants, but new policies, such as carbon emissions reduction targets, and advancing technologies are forcing grid operators to seek a new paradigm. Buildings use 75% of U.S. electricity and must be a critical part of the solution as we work to decarbonize and transform our energy system.

Under the GridOptimal Buildings Initiative, new metrics are now available to help define the new normal for the building-grid interaction by providing guidance on how to measure and quantify building features and operating characteristics to support more effective and cleaner grid operation. These metrics will support the least-cost use of renewable resources through better building-grid integration. By creating a standardized set of metrics that define a building’s contribution to the relevant utility grid scale—the building’s operational performance as a grid asset—many doors open. Utilities may incentivize grid-sensitive design. Government agencies may include the metric in their procurement requirements or in their climate policies. Designers and building owners can consider these project impacts in a sensible, straightforward approach.

These metrics are the result of months of work and in-depth deliberations with experts from across the country, through the GridOptimal Technical Advisory Committee (TAC). GridOptimal TAC members have helped us develop and refine our approaches. The GridOptimal Buildings Initiative Founding Sponsors have generously contributed financial support and enabled GridOptimal to make this progress.

Introducing the GridOptimal Metrics (as of May 2020)

There are currently eight core GridOptimal metrics that are scored on a scale of 0-100%. These combine two basic approaches to evaluate the quality of building-grid interactions: (1) building energy consumption patterns (load shape or demand profile), and (2) building assets (capabilities).

Building energy consumption patterns
Four of the GridOptimal metrics (the first four in the table above) apply load shape evaluation calculations for each of the 8,760 hours in a year. Some hours may matter more than others in terms of how stressed the grid is and how much carbon is emitted. For example, in many grid locations peak hours occur on hot summer afternoons. During these afternoons, every grid resource is delivering power, including the most-expensive, least-efficient, highest-emission power plants. Energy savings in a building during this hour would matter more in terms of cost and carbon emissions reductions than energy saved on a temperate spring day when system loads are lower, and the grid is cleaner and cheaper to operate. Each hour of the year is assigned a value for each metric, based on the characteristics of the local grid (in terms of system loads, grid carbon, or other parameters). The building’s performance is then evaluated for each hour and assigned a single score for the year for each metric.

Building assets
The other four GridOptimal metrics have to do with the building’s capabilities or assets, rather than its load shape. These metrics are intended to directly measure the building’s potential to serve as a grid resource. For example:
• Can the building modify its load shape over a specific time period? How much?
• Can it do so based on an automated signal from a third party?
• Can the building island (safely disconnect) from the grid?

Entering a New Phase

Currently, NBI and USGBC are deeply engaged in work to determine what constitutes typical and exemplary performance in each of these metrics in hundreds of different situations (across different climate zones, electricity grid locations, onsite renewable energy generation profiles, building performance levels, etc.). Once that is complete, we will work with USGBC to use these metrics in a proposed pilot credit (new LEED credit) to understand how these metrics work in the field and to document benefits to project teams, grid operators, and the environment. We are currently seeking pilot projects. In parallel, we will be developing utility program criteria so that utilities can leverage this work to encourage building designers, builders, owners, and operators to improve their grid interactivity capabilities and performance outcomes.

The methodology of each metric will be explained in further depth in a conference paper in August 2020 as part of the ACEEE Summer Study on Energy Efficiency in Buildings. To learn about what a pilot project might look like, watch our on-demand webinar. If you have a project currently or will have one designed soon that you would like to submit for a LEED pilot credit, please reach out to us.

By Alexi Miller, Senior Project Manager