To futurefit our home (remodel for the future) to the Passive House Standard, we air sealed to reduce air leakage by a factor of 5.  Without this “accidental ventilation” we needed to add balanced, mechanical ventilation with heat recovery.  At the time, no UL-listed heat recovery ventilator (HRV) was available with the necessary combination of 75%+ effective heat transfer and low electrical consumption.  The ZehnderAmerica CA 350 HRV was certified by the Passivhaus Institut (PHI) for superior performance, but it was not tested and listed by Underwriter’s Laboratory (UL).  The City of Portland allowed us to install it without UL listing as an alternate material through its Alternative Technology Advisory Committee (ATAC) process.  We enjoy superior ventilation, indoor air quality, and energy efficiency with our HRV.