Our expertise · Green Building & Affordable Housing
Phius Consulting & Passive-Building Support
Passive performance is decided in the details. Coordinate them before they are built.
Phius certifies passive buildings, new construction and retrofits alike, whose performance comes from the enclosure, thermal-bridge control, ventilation and systems working together, and it verifies in the field that the building was built the way it was modeled. Those results live in details that are hard to change after installation, so the design, builder and verification team have to agree how each critical detail will be executed and documented before construction starts. Developers, owners, builders and housing organizations pursue Phius when they want the performance itself, not just a label. Green Summit supports Phius teams with building-performance consulting, energy analysis, enclosure and systems coordination and documentation as a licensed engineering firm and RESNET Rating Provider, and we establish the required consultant, rater or verifier roles before any work is assigned; Phius reviews and certifies the project.
- RESNET Rating Provider No. 1998-221
- Licensed engineering firm
- Founded 2014
- Audit-ready documentation
Who this is for
Developers, owners, builders and design teams committed to a Phius target on new construction or a retrofit, affordable-housing and Tribal housing organizations, and raters building passive-building skills.
What we do
- Review the project pathway. We identify the building type, the new-construction or retrofit context and the certification process that applies.
- Coordinate performance decisions. We review envelope, thermal-bridge, ventilation and system decisions within the technical scope of your engagement and coordinate the modeling approach the program accepts.
- Plan construction and verification. We establish the field-observation, testing, commissioning and evidence needs with the qualified project professionals before the schedule is set.
Our process
- Set the target and the team. We establish the certification target and the qualified project team, including the Phius rater or verifier the project requires, before any certification-related work begins.
- Coordinate analysis and design decisions. We work through the performance-sensitive details, envelope continuity, thermal bridges, ventilation and system selections, before construction details are fixed.
- Maintain the record. We carry the record through field verification, as-built updates and final review, so the documented building matches the one that was modeled.
Benefits
- Earlier visibility of the design decisions that drive passive performance.
- A coordinated handoff between design and field verification, so the verifier sees what the designer intended.
- A clear distinction between modeling, construction and certification responsibilities.
- Diagnostic testing, energy modeling and commissioning coordination from one team, within the roles the project establishes.
- An as-built record that shows the verifier, the owner and Phius the same building the model described.
Why Green Summit
Green Summit brings building science, diagnostic testing and engineering coordination together in one licensed engineering firm, founded in 2014 and RESNET Rating Provider No. 1998-221. Phius-specific services are delivered within the qualifications and roles established for the project, never assumed from a HERS credential alone.
Our role starts with the pathway review and ends with the as-built record for final review. We coordinate the analysis, the details and the evidence, and we build the record to be audit-ready from day one; Phius certifies the building.
Frequently asked questions
What is Phius certification?
Phius is a passive-building certification for new-construction and retrofit projects. A project sets a performance target, designs the enclosure, thermal-bridge control, ventilation and systems to meet it, and is verified in the field by a qualified Phius rater or verifier before final review. Green Summit provides the consulting, analysis and coordination around that process; Phius makes the certification decision.
Is Phius the same as a HERS Rating?
No. A HERS Rating and Phius certification have different purposes and requirements. Rating or testing work, such as blower-door testing, may support the project, but it never replaces Phius certification, and a HERS credential alone does not qualify anyone for the Phius roles.
Who performs the required field verification?
The qualified Phius rater or verifier for the project's type and scope. We establish that arrangement before committing to any certification-related work, and we say plainly which parts of the field work sit with that verifier and which sit with us.
Can Phius apply to rehabilitation?
Yes. Phius offers retrofit-related pathways as well as new-construction approaches. We identify the current program and the project's conditions rather than reusing a new-construction checklist, because an existing enclosure raises questions a new one never does.
Why start before construction?
Because envelope continuity, ventilation and system choices are difficult to change after installation. Early coordination lets the design, builder and verification team agree how the critical details will be executed and documented, while a detail can still be redrawn instead of rebuilt.
Can the work connect to a broader capital plan?
Yes. Decarbonization and eligible financing analysis can help you compare the Phius pathway with ownership objectives, replacement cycles and project costs, and we evaluate those questions alongside the certification work rather than after it.
Let's coordinate the details before they are built.
Tell us the building type and location, whether it is new construction or a retrofit, and the performance target or certification commitment you are working toward.
Related solutions
- Green Building Consulting & Certification Strategy
- Energy Modeling
- Residential Blower-Door Testing
- Building Systems Commissioning & Functional Verification
- Decarbonization Consulting
- C-PACE Advisory & Financing Support
Program and technical references
Phius Certification Guidebook v25.1.0
Program information reviewed September 22, 2026. Current applicability, qualifications and program terms are confirmed for each engagement.
Or call 321-273-2200 · inquiry@greensummit.com