LEED Zero: An Orientation

USGBC’s LEED Zero program provides a path for buildings to distinguish themselves with a net-zero impact for carbon, energy, water, and/or waste. To pursue any of the LEED Zero certifications, a building must already be certified under LEED for Building Design and Construction (BD+C), LEED for Existing Buildings: Operations and Maintenance (O+M), or be registered for LEED O+M. So, although it’s a stand-alone program, LEED Zero actually acts more like a complement or extra credential to your building’s standard LEED certification. For buildings with a BD+C certification, LEED Zero presents an alternative to LEED O+M for demonstrating a continued commitment to sustainability in operations.

Here are a few of the basics to keep in mind.

Zero Carbon

LEED Zero Carbon is achieved when your building’s annual carbon balance is zero. A zero balance means that you have offset all emissions, measured in carbon dioxide equivalent (CO₂e), resulting from your building’s operations.

An interesting component of LEED Zero Carbon is that, in addition to accounting for building energy emissions, you also must account for the emissions resulting from occupants commuting to the building. Given that, you’ll need to track ongoing building energy use and complete an occupant commuting survey each year to understand the full emissions attributable to your building. Emissions stemming from water consumption, waste generation, and the embodied energy of the building are planned but not yet incorporated into the program.

How to get there?

The first strategy to reduce emissions for any building should be energy efficiency. Efficiency measures have the benefit of providing a return on investment, and can often be implemented at a lower cost compared to on-site renewables. But to reach a carbon balance of zero, your team will need to implement a renewable-energy and carbon-offset strategy–regardless of how efficient your building is. LEED Zero Carbon recognizes each of the renewable strategies below, in order of priority, for reducing emissions.

1. Onsite renewable generation
2. Local renewable generation, such as community solar or wind
3. Offsite generation projects, such as through power purchase agreements
4. Purchased energy attribute certificates (EACs, which are synonymous with renewable energy certificates, or RECs, in the context of the LEED Zero program)
5. Purchased carbon offsets

Although LEED Zero Carbon has established the above priorities, the weighting or relative value of each option is the same in the program’s calculations. In other words, 1 kWh of onsite generation is generally counted the same as 1 kWh of purchased EACs. But although the different strategies are weighted the same, the location where the renewable energy is generated is an important consideration. This is because the program’s calculations account for the emissions factors associated with your building’s location and the recipient grid for purchased renewables. Keep this in mind for your project, especially before purchasing offsite renewables.

Zero Energy

LEED Zero Energy is very similar to LEED Zero Carbon, with one key exception.

The program addresses the balance of source energy used on the site, rather than emissions. Source energy represents the total amount of raw fuel that is required to operate the building. It incorporates all transmission, delivery, and production losses. So activities like occupant commuting are not included, and the grid emissions factor for the building’s location—or the recipient grid of any offsite purchased renewables—are not included in the calculations.

The renewable-energy strategies allowed to achieve net-zero source energy use include onsite renewables, local generation, and offsite generation.

Zero Water

LEED Zero Water buildings achieve a potable water balance of zero annually. To achieve that balance, projects can leverage the following strategies.

1. Reclaimed water from offsite. The most common example of this is a municipality that develops infrastructure to treat and reuse wastewater within its district. This reclaimed water is suitable for applications such as irrigation, manufacturing, and other non-potable purposes. These types of systems are also sometimes referred to as “purple pipe.”
2. Onsite water capture and reuse. Most commonly, projects collect, treat, and reuse water from sources such as rain and stormwater, nuisance groundwater, and condensate or blowdown water from building HVAC systems.
3. Wastewater that is treated onsite and sent back to the original water source.

Although offsite water-replenishment or water-balance actions are not included as contributing strategies, these actions are emerging as an important component of meeting organizational sustainability goals and may become relevant for programs like LEED Zero with future iterations. The World Wildlife Fund has developed a good resource on water-balance targets and corporate strategy, which can be accessed here.

Zero Waste

LEED Zero Waste requires successful achievement of Platinum-level certification in the TRUE Zero Waste program, which is also administered by GBCI.

TRUE Zero Waste is a credit-and-prerequisite-based system like LEED that requires a minimum waste diversion rate of at least 90%. TRUE Zero Waste employs a combination of tactical and performance-based criteria with a focus on embedding best practices across operations. Buildings with robust waste management programs, engaged occupants, and proactive waste haulers will be the best candidates for the TRUE program, and will have a shot at achieving the Platinum-level certification required by LEED Zero Waste.

Certification Logistics

Projects pursuing certification under the LEED Zero Carbon, LEED Zero Energy, or LEED Zero Water programs must register through LEED Online and provide 12 months of metered performance data. Projects pursuing LEED Zero Waste must submit documentation of their TRUE Zero Waste Platinum certification. Additional documentation guidance is provided in USGBC’s LEED Zero Program Guide.

The LEED Zero programs verify a building’s performance over a 12-month period. We expect that projects making a claim around the certification would therefore tie the certification to a specific year, and continue to recertify on an annual rolling basis.