How does an IECC 2018 building enclosure hold up against a Passive Building (Phius) Enclosure? And what matters most, U-Value, R-Value or Air Leakage?

Our client's wanted a healthy home for their children - bringing in fresh filtered outdoor air for the highest indoor air quality was something we wouldn't compromise on.

Multi-family buildings larger 12,000 sf require Phius Core or PHI certification under the residential specialized code in Massachusetts to receive a permit and allow occupancy after construction.