Paul Jennings of Aldas is one of the most experienced airtightness tester and consultant in the UK, with over 30 years’ experience. He presents at numerous Passivhaus and AECB events in the UK and overseas. Paul has been involved in most UK Passivhaus projects to date in one or more capacities, including: • the first UK certified domestic and non-domestic PH projects in Machynlleth, initially tested in 2008, retested in 2018 • Erneley Close in Manchester, the most successful UK EnerPHit block refurbishment project to date • Agar Grove PH area regeneration in Camden, ultimately delivering more than 500 newbuild PH units • the Exeter Passivhaus swimming pool and leisure centre, currently under construction. Paul is an experienced trainer and originated the Airtightness Champion concept, as well as delivering the Airtightness Masterclass for the PHT, with Stephen Gurney. He developed the 12 Steps to Airtightness approach to enable UK contractors to reliably deliver airtightness in Passivhaus and other low-energy projects.