Interview with Kristof Irwin, Principal of Positive Energy and also a Professional Engineer and Mechanical Engineer, and Host of The Building Science Podcast. We learn from our interview about air exchange in homes, humidity, house energy efficiency, what MEP is, why we should all care about the air quality in our homes and how we make it high quality, and hear stories about best practices in construction science. The mechanical, plumbing, and electrical installations greatly influence the experience of living and being in our homes.