Graham Irwin, AIA, CPHC, is the principal of Essential Habitat Architecture, a Northern California practice focused on healthy, high performance, sustainable buildings built to Passive House standards. He has a degree in physics, with additional studies in engineering and architecture, and an extensive background in software development. His firm has worked on numerous single-family, multi-family and commercial Passive House projects throughout California and the US, including the first certified Passive House in California, the first certified Passive House retrofit in the US, and the first certified multi-family Passive House in the US. He is a licensed architect and licensed general contractor in the state of California. Graham has presented extensively at Passive House conferences, both nationally and internationally, since 2009.