This online course is designed to expand on the knowledge gained in Building Science Level 1. After completing this course, participants will be able to understand the building science concepts of House as a System as it applies to building science principles and energy efficiency. The course will also expand on the building science principles of air flow, heat flow, and moisture flow, and the impact that they can have on a structure. Participants will learn how treating the House as a System can impact Indoor Air Quality and the health and comfort of the occupants. Participants will also be introduced to diagnostic tools, such as blower door and infrared imagers, that can help ensure accurate diagnosis and correction of issues that are unique to each particular structure. This course requires each participant to complete all modules and earn a grade of 70% or above in the end-of-course exam.