The Passivhaus-Institut (PHI) is responsible for promoting and maintaining the Passivhaus building program.[1][2][3] The "Passivhaus Institute" was founded in 1996, and is based and active in Darmstadt, Germany.
The English spelling was used for the Passive House Institute US (PHIUS) when it formed in 2007 [4] originally under the umbrella of the Passivhaus Institute. The two separated in 2012.