GHI Zero Carbon Certified
Net-zero operational carbon emissions, accounting for both energy use and grid mix.
Description
The GHI Zero Carbon Certified badge recognizes homes that achieve net-zero operational carbon emissions — accounting not just for kWh consumed but for the emissions intensity of those kWh on the local grid. It is administered through GreenHome Institute alongside Zero Energy Certified and aligns with the U.S. Department of Energy's Zero Emissions Building (ZEB) definition: energy efficiency + electrification + renewables (on-site or off-site through RECs).
The badge differs from Zero Energy Certified in two important ways. First, off-site renewables and Renewable Energy Credits (RECs) count toward the offset — generation does not need to be on-site. Second, the accounting is carbon-weighted rather than kWh-weighted: a home in a coal-heavy grid region needs more offsets than the same home in a hydro-heavy region, even with identical consumption.
Embodied carbon is currently treated as "part two" of the standard and is under separate development by DOE; the GreenStar embodied-carbon requirement is the most relevant overlap until that update lands. GHI has stated the badge will be updated to match the final DOE ZEB definition as it stabilizes.
Required standard requirements
To earn this badge, the project must meet all of the following existing GreenStar requirements:
Additional badge criteria
Beyond the required standard requirements above, the project must also satisfy:
Performance & verification
- 01.
All-electric construction. Operational fossil-fuel combustion at the dwelling cannot be offset under this badge — combustion appliances disqualify the project regardless of how renewables are sourced. (Same multifamily exceptions as Zero Energy Certified apply.)
- 02.
Existing homes: ENERGY STAR Home Energy Score of 75 or higher (requires 12+ months of utility data) — OR demonstrated 35% reduction below the regional median Energy Use Intensity for projects without sufficient utility history.
- 03.
New construction: energy model demonstrating operational carbon emissions of zero on an average-year basis, using grid-emissions factors for the project's eGRID region. Approved modeling tools match the Zero Energy Certified program list.
- 04.
Third-party verification: building envelope air leakage, duct leakage, and combustion-safety testing (the last where any combustion appliance remains under exceptions).
Renewable accounting
- 01.
On-site renewable generation is preferred but not required. Off-site renewables qualify if backed by retired RECs (Green-e Energy certified or equivalent).
- 02.
Community-solar subscriptions qualify if the associated RECs are retired on the homeowner's behalf.
- 03.
RECs must cover 100% of the home's modeled annual grid electricity use, measured in MWh and matched to a renewable source within the same grid region where practical.
Documentation
- 01.
Energy model output showing modeled annual kWh consumption, eGRID emissions factor used, and resulting tCO₂e/year — net of any on-site PV production.
- 02.
REC purchase certificates or community-solar subscription agreement showing the project address and the MWh allocated.
- 03.
Base certification through GreenStar Homes, LEED, NGBS, Enterprise Green Communities, Passive House, or equivalent.
- 04.
Note on evolving criteria: until GHI publishes the final DOE-ZEB-aligned criteria, this badge is reviewed case-by-case by the GreenHome Inspector. Pre-registration consultation with GHI is recommended.
Verification by tier
Evidence the project team submits at each certification tier. Cumulative — higher tiers include everything below unless noted otherwise.
-
Certified
Self-attestation- 01.
Owner-signed all-electric appliance inventory.
- 02.
Project eGRID region documented; emissions-factor worksheet attached.
- 01.
-
Silver
Documents + photos- 01.
REC purchase certificates (Green-e Energy certified) OR community-solar subscription agreement showing the MWh allocated to the project.
- 02.
New construction: energy model with operational-carbon output in tCO₂e/year.
- 03.
Existing homes: 12-month ENERGY STAR Home Energy Score showing ≥ 75 — or EUI worksheet showing 35% below regional median.
- 01.
-
Gold
Third-party test- 01.
Third-party verification of envelope air leakage, duct leakage, and emissions-model inputs.
- 02.
GHI Inspector case-by-case review (badge is in flux pending final DOE-ZEB-aligned criteria).
- 01.
-
Platinum
Post-occupancy verification- 01.
12-month measured-vs-modeled utility data with updated REC retirement to cover any drift.
- 02.
Annual recertification through GHI as long as REC coverage is maintained.
- 01.