PHIUS

PHIUS stands for Passive House Institute US, a United States–based non-profit organization that administers the certification of the Passive House standard for North America. It operates within the global Passive House Institute network and adapts the standard to local climate conditions and building practices. The organization certifies buildings, components, and professionals to the PHIUS+ standard, which is a version of the Passive House criteria tailored for the U.S. market.

The PHIUS certification process requires projects to meet rigorous performance targets for the building envelope, airtightness, and ventilation with heat recovery. It covers both new construction and major renovations and involves documentation of design intent, energy modeling aligned with the PHIUS+ criteria, and field verification such as airtightness testing and verification of proper ventilation operation. Certification is awarded when the project demonstrates compliance with the standard, and ongoing verification is often pursued to confirm post-construction performance.

PHIUS emphasizes climate-specific design criteria to address the diverse North American climates, aiming to minimize space conditioning energy while maintaining indoor comfort. The standards encompass residential, commercial, and institutional buildings, as well as guidance for windows, thermal bridging, and ventilation strategies. In addition to certification, PHIUS provides training and professional certification programs for designers, consultants, and builders, along with resources, best-practice guidance, and project registries.

Through its certification programs and educational offerings, PHIUS seeks to promote the adoption of high-performance, low-energy buildings across the United States and Canada, aligning with broader efforts to improve energy efficiency in the built environment.