This is class 4 of 6 in 3C-REN’s High Performance Fundamentals Certificate series. The class will cover what a heat pump is and explain why heat pumps are essential elements of high performance buildings. Special attention will be paid to refrigerants: how heat pumps use them, how to avoid leaks through proper installation, and why it’s important to avoid leaks due to the damage they can cause to contractor profitability and the planet. An overview will be provided to aid in selecting, sizing, installing, and commissioning heat pump equipment, so that it performs as intended.