An HVAC system is only one part of a home. Insulation, air leakage, windows, ducts, ventilation, moisture, solar exposure, and occupant behavior can all affect how well heating and cooling equipment performs. When these conditions are overlooked, even properly installed equipment may struggle to provide expected comfort, efficiency, humidity control, and indoor air quality. Designed for HVAC professionals who are new to building science, this webinar will introduce the house-as-a-system approach and explain how building conditions influence HVAC loads and performance. Using practical examples, participants will learn what to look for before recommending or replacing equipment, how improvements to the home can affect HVAC needs, and when coordination with a building performance professional may improve the outcome. Learning Objectives: – Explain how the building enclosure and HVAC system work together. – Identify building conditions that affect HVAC sizing and performance. – Recognize how coordination between HVAC and building improvements can improve comfort, safety, and efficiency.