This publication provides introductory technical guidance for mechanical engineers and other professional engineers and construction managers interested in energy efficiency upgrades for air conditioning systems in buildings. Here is what is discussed: 1. OVERVIEW OF AIR DISTRIBUTION SYSTEMS, 2. AIR HANDLING SYSTEM TYPES, 3. AIR DISTRIBUTION SYSTEM FANS, 4. FILTERS, 5. INSTALL VARIABLE-SPEED DRIVES, 6. MODIFY CONTROLS, 7. PICK PREMIUM EFFICIENCY MOTORS, 8. USE ENERGY-EFFICIENT BELT DRIVES, 9. CONSIDER A TESTING, ADJUSTING, AND BALANCING, 10. SUMMARY, 11. BIBLIOGRAPHYAbout the Author: Paul Guyer is a registered civil engineer, mechanical engineer, fire protection engineer and architect with 35 years of experience designing buildings and related infrastructure. For an additional 9 years he was a principal staff advisor to the California Legislature on capital outlay and infrastructure issues. He is a graduate of Stanford University and has held numerous national, state and local offices with the American Society of Civil Engineers, Architectural Engineering Institute and National Society of Professional Engineers. He is a Fellow of ASCE and AEI.