Passive House Systems wins airtightness certification from PHI

This article was originally published in issue 52 of Passive House Plus magazine. Want immediate access to all back issues and exclusive extra content? Click here to subscribe for as little as €15, or click here to receive the next issue free of charge

The Polaris system comprises three components: the PHS Polaris Air Block membrane, a double-layer vapour control layer combining a PE film with a PP non-woven fabric; the PHS Argo Plus multi-tape, a UV-stabilised, PET-reinforced adhesive tape for joining overlaps and penetrations; and PHS Ottello, a solvent-free, permanently elastic adhesive sealant for bonding the membrane to substrates such as concrete.

Tested by the Passive House Institute in Darmstadt in December 2025, the system achieved the highest available classification, phA, with an average air permeability of 0.01 (±0.009) m³/(hm²) at 50 Pa across three connection types: membrane to membrane, membrane to OSB, and membrane to concrete. The phA threshold sits at ≤0.10 m³/(hm²). The membrane’s own airtightness figure, below 0.01 m³/(m²h) at 50 Pa, was excluded from the system average, as the certification tests the assembly rather than the individual material in isolation.

The membrane carries a fixed Sd value of 9 m and a μ-value of 25,000, and is CE-marked to ISO EN13984. It is suited to vented flat ceilings and pitched roofs across block, steel, and timber frame construction. The Argo Plus tape has a temperature resistance range of -40°C to 80°C and is rated for use both indoors and outdoors.

“The PHS Polaris system was developed in response to market demand, especially with our timber-frame customers who show a preference for 3 m wide PHS Polaris membrane,” said Scott Reece, Passive House Systems’ sales and operations manager for the UK, “we are delighted the system has attained PHI certification which compounds our commitment to innovation and quality.”