Phius CORE

In the past, the Phius standard has been strictly performance based and required setting performance limits and whole-building energy modeling to verify compliance with those limits. In 2021, Phius released the first ever prescriptive passive building standard. Phius CORE Prescriptive was created to facilitate widespread adoption and scaling up, placing emphasis on quality, durability, health, safety, and cost-optimized conservation on the path to zero energy. That standard, along with all the other Phius standards, received updates in 2024.

The prescriptive program was designed with the intention that projects that pursue either the performance (Phius CORE) or prescriptive (Phius CORE Prescriptive) path achieve the same level of building performance. The primary difference between the programs is the way that passive and active measures are regulated -- by individual items, subsystem performance tradeoffs, or by whole-building tradeoffs.

Phius CORE is available for all new construction projects.

Certification under Phius CORE Prescriptive is limited to single-family dwellings – detached or attached housing such as side-by-side duplexes or townhomes. Other notable limitations are the ratio of floor area to bedrooms, limits on window and skylight area and orientation and limits on "noncompactness" or building form.