Finally, a Clear Zero Emissions Standard! And LEED v5 Is on Board

Decarbonizing the built environment is an essential part of achieving national goals to reduce U.S. building emissions by 65% by 2035 and 90% by 2050. The built environment currently contributes approximately 42% of U.S. greenhouse gas emissions (GHGs).^[1] Included in this total are direct on-site emissions (Scope 1), indirect emissions from the purchase of energy (Scope 2), plus total indirect upstream and downstream emissions: including construction, transportation, and other supply-chain-related emissions (Scope 3).

In recent years, the emphasis on achieving zero emissions has reached a fervor, with multiple green building certifications, standards, codes, and local incentive programs all calling for zero-emissions buildings. Meanwhile, there’s growing disagreement about what we’re even measuring: is zero emissions for energy in individual buildings on its own a worthy goal, when what we actually need is to reduce GHGs in total?

If you have waded into these waters, you quickly find that navigating the requirements for achieving a zero-emissions building is complex. Each definition or standard attempts to be the definitive version, but each has slightly different language. ASHRAE Standard 228 is just one recent example. Here are just a handful of the tricky questions that come up:

• Does any given standard address zero operational energy only, or does it include or focus exclusively on zero operational carbon?
• Do standards apply to measured values from existing buildings or only to the estimated emissions of new projects?
• Is the measure of operational energy based purely on what’s used onsite (“site energy”), or does it include the energy losses associated with generating and transporting fuel and electricity to the building (“source energy”)?
• Do renewables have to be located onsite to count as clean energy for a project?
• What energy uses and emission sources have to be included? Does electric vehicle charging count?
• What about embodied energy and carbon, and other emissions associated with building materials and construction?

While everyone means well, the current landscape is confusing and is creating unnecessary stagnation.

DOE’s new resource for aligning on zero carbon

Enter the Department of Energy!

It has been six months since the U.S. Department of Energy (DOE) set forth Part 1 of a National Definition of a Zero Emissions Building (from here on out, “the DOE Definition”) creating a national framework that can be adopted across government jurisdictions and voluntary programs.

Part 1 addresses operational carbon—the emissions associated with heating, cooling, lighting, and other core building functions. It is anticipated that future parts of the DOE Definition will address embodied carbon (emissions associated with building materials and construction processes). Other future DOE Definition sections may look at fugitive emissions (leaks) from HVAC and refrigeration systems and at the beneficial impacts of grid interactivity (onsite management of energy use and/or storage to support a cleaner electrical grid).

In the meantime, Part 1 of the DOE Definition sets forth three criteria for buildings to achieve to claim zero operational GHG emissions. At a minimum, a Zero Emissions Building must be:

1. Energy efficient
2. Free of on-site emissions from energy use
3. Powered solely from clean energy

Here’s what it all means for our projects—including those pursuing LEED.

An important preface to the DOE Definition

The DOE Definition is only a blueprint, not a regulatory standard. It is designed to align the building industry around a common understanding of what it means to be a zero-emission building. The agency will not assess or certify whether a building satisfies the definition. Instead, the DOE Definition offers guidance to public and private entities to determine whether a building has zero emissions from operational energy use.

Each organization or jurisdiction will determine how to document and verify that a particular building meets the criteria. Many organizations have already begun to adopt the definition’s language—including the creators of LEED.

1) Energy efficiency in the DOE Definition

The energy-efficiency part of the DOE Definition applies to both new and existing buildings, with different requirements for each.

Existing Buildings must achieve one of the following, all of which are based on its measured site energy use intensity (EUI)—the average annual energy consumed per square foot or square meter by that building, without counting any estimates of energy lost when electricity is generated or transmitted.

• An Energy Star score of 75 or higher​.
• For building typologies not covered under the Energy Star program, a site EUI that’s at least 35% or better than the median EUI for buildings of that category​.
• For any building, whether Energy Star covers the typology or not, there is also an alternative path: an EUI less than that specified in the latest version of ASHRAE 100 (currently in its 2024 edition), Energy and Emissions Building Performance Standard for Existing Buildings.

New buildings must satisfy one of the following:​

• Its modeled energy use is at least 10% lower than that required in the most recent version of ASHRAE 90.1 (currently in its 2022 version).
• It is designed to achieve an Energy Star score of 90 or higher​.
• It is a residential project that has been certified under the latest version of one of these programs:
  • Energy Star Residential New Construction (current versions are 3.1 for single-family homes and 1.1 for multifamily buildings).
  • Zero Energy Ready Home​ (currently in version 2).

2) On-site emissions from energy use in the DOE Definition

Direct GHG emissions from operational energy—such as carbon and methane emissions from burning gas—must equal zero, with one notable exception.

Although the DOE Definition encourages clean sources of emergency power, its on-site combustion ban exempts backup generators​. This is because there are a limited number of renewable backup generation options that meet local code requirements.

3) Powered solely from clean energy

All energy used by a building must be “clean”—meaning it emits no GHGs—but can be procured through a combination of on-site and offsite sources. On-site clean energy is encouraged, but not required, before procuring offsite clean energy.​

To qualify as clean energy, each offsite source must meet one of the following sets of requirements. Notably, some of these guidelines are more or less stringent than others in terms of how offsite energy is defined.

• ANSI/ASHRAE Standard 228, “Standard Method of Evaluating Zero Net Energy and Zero Net Carbon Building Performance,” Sections 8.3 to 8.5 lays out the rules for buildings to meet Zero Net Energy and Zero Net Carbon. Community solar, PPAs, VPPAs, and renewable energy certificates (RECs) are all considered offsite renewable under this standard. There are strict rules regarding retiring RECs.
• Partnership Requirements for the U.S. Environmental Protection Agency’s (EPA) Green Power Partnership defines how private organizations with large electricity demand can comply. Community choice aggregation, competitive supplier green power products, power purchase agreements, self-supply, shared renewables, utility green power products, utility green tariffs, and RECs are all considered offsite renewable under this standard. The GPP Guide to Making Claims includes high-level guidance around retaining RECs.
• “Green-e Renewable Energy Standard for Canada and the United States”  is a certification framework that determines proper sources of clean energy and facilitates the sale of clean energy separate from its associated RECs. Green-e renewable meets all qualifications of EPA partnerships.
• Sections 4.2.4 to 4.2.7 of “Implementing Instructions for Executive Order 14057”  offer guidance for federal clean-energy procurement that also permits purchase of RECs not tied to the actual energy used onsite—though these RECs only count if they’re from an energy source that’s in the same grid region as the building. It is typical for the government to have RECs purchased from energy sources in the same independent system operator (ISO) region, and it is a requirement that will become more prevalent outside of government purchase.

Under the DOE Definition, on-site EV charging stations do not have to be included in these energy calculations. Therefore, their energy use is directly tied to the local grid source (a positive or negative depending on where the project is located and the fuel makeup of the grid).

Carbon offsets are not permitted under the DOE Definition. This means that all off-site energy use must be secured from a documentable “clean” source with no GHG emissions.   

Three things to note about the zero emissions DOE Definition

One, the DOE Definition does not include specific guidance around how REC ownership is treated for on-site generated energy. LEED clearly states in v4, v4.1, and the draft v5 that RECs for on-site generation cannot be sold in order to get the Energy and Atmosphere Renewable Energy credit. This functionally means that the renewable energy from the building is retained by the building and cannot be counted in the renewable energy calculations of another building or entity. No double dipping! By leaving this ambiguous under the DOE Definition, installing renewable energy may be encouraged for buildings that don’t have the financial capacity to develop without the additional financial incentive that RECs provide—but also wades into muddy waters in terms of the increasingly strict standards for renewable and carbon accounting under LEED and other frameworks like the Greenhouse Gas Protocol (GHGP) and Science-Based Targets Initiative (SBTi).

Two, the DOE Definition does not explicitly define the importance of where the RECs used to achieve offsite renewable energy claims are located. This is of growing interest in the industry—as it better ensures that renewable development is occurring in grid areas that need it, prevents grid renewable saturation, improves traceability and verification of actual energy and carbon impacts, and reduces the likelihood of double-counting renewable energy claims.   

Three, for offsite renewable energy generation, the qualifying RECs listed vary widely in their treatment of the issue outlined above regarding ownership and retention. This offers more opportunities for organizations to readily choose RECs based on their budgets and markets, but once again runs the risk of multiple buildings counting the same unit of renewable energy as their own.

What does this mean for LEED v5?

USGBC announced at Greenbuild 2023 that LEED v5 would align with the national definition, “including requirements for LEED Zero Carbon and Platinum-level projects that specify low [or] operational GHG emissions.”

How is this going to be incorporated into the LEED rating system? Take a look below for a few examples.

LEED v5 BD+C

The core principles can be seen within the Energy and Atmosphere category of the LEED v5 Second Public Comment draft. There are also elements in the new  LEED v5 Second Public Platinum Requirements for the Energy and Atmosphere Enhanced Energy Efficiency credit and the Energy and Atmosphere Renewable Energy credit, as well as limitations to on-site combustion and coefficients of power (COP) and the Materials and Resources Reduce Embodied Carbon credit.

Looking specifically at  the LEED v5 Enhanced Energy Efficiency credit for Option 2: Energy Simulation, the credit language uses similar metrics for some of the minimum requirements as the DOE Definition (which requires modeled energy use for new buildings). An important element to keep in mind for teams looking to align with the DOE definition is the fact that the unit of evaluation for LEED remains source energy, while for the DOE Definition it uses site energy. However, the LEED v5 Second Public Comment draft offers a conversion ratio for electricity site-to-source energy.

Notably, site energy reductions are most impacted by building-related efficiency measures. Source energy reductions are impacted by the entire supply system, where increasing the reliability and efficiency of the energy sources themselves contributes to overall reductions. Additional useful information from both the EPA and DOE about the distinction is available.

Ultimately, LEED v5 gives more weight to energy reductions for Platinum ratings. It aligns the EA credits with the current LEED Zero Energy rating and creates a pathway for alignment with the DOE Definition.

In addition, because of the discrepancies between site and source definitions, LEED across versions remains a valuable contributor to the definition of zero-emissions buildings, as opposed to directly aligning with the DOE’s definition.

LEED v5 O+M

To hit Platinum under LEED O+M LEED v5 Second Public Comment draft, it’s a similar but more complex story.

In the Optimized Energy Performance credit, a minimum Energy Star score of 79 (7 points) must be achieved for Platinum, although this is not the highest threshold. An Energy Star score 92 will earn a project the full 12 points under LEED v5 Second Public Comment draft, and 85 will qualify the project to attempt LEED Zero Carbon (also according to the latest draft).

In addition, a project must earn a minimum of 2 points or equivalent under the new GHG Emission Reduction Performance credit in Option 1: Greenhouse Gas Emissions from On-Site Combustion, 2 points in the GHG Emissions Reduction Performance credit in Option 2: Renewable Energy, and 2 points in the Decarbonization and Efficiency Plans credit.

Meanwhile, if the GHG Emission Reduction Performance credit achieves the full 6 points for Option 1: Greenhouse Gas Emissions from On-Site Combustion and (depending on the selected REC standard) associated points for Option 2: Renewable Energy, the project would align with the DOE Definition.

LEED v5 Zero Energy and Zero Carbon

LEED Zero Energy recognizes “source energy use balance of zero over a period of 12 months,” while LEED Zero Carbon “recognizes net zero carbon emissions from energy consumption through carbon emissions avoided or offset over a period of 12 months”  (with pending updates). Outside of LEED v5 updates related to LEED certification prerequisites, these certifications meet only criteria 2 (Free of On-Site Emission from Energy Use) and 3 (Powered Solely from Clean Energy). LEED Zero does not require efficiency ratings (though it is recommended), and therefore does not satisfy the DOE Definition of criteria 1 (Energy Efficiency). It remains to be seen if further updates to these programs will align to the DOE Definition for efficiency, but it appears that USGBC is moving in that direction based on the LEED v5 prerequisite and credit drafts.

What this means for the AEC industry moving forward

Tackling building-related emissions is one of the biggest hurdles to achieving a zero-emissions economy by 2050. The DOE Definition can serve as a guiding light for professionals in the complex landscape of certifications and standards. It is a step in the right direction for pushing the AEC industry toward a zero-emissions future.

Yet the definition does require the industry and non-federal jurisdictions to adopt the definition into their respective standards, codes, and action plans in order to be effective. With widespread adoption of the definition, the AEC industry can create a path forward for decarbonization.