Central ventilation systems in multifamily buildings are a vital building system that often compromises overall building performance (ie they don’t perform to code almost 100% of the time). Correcting ventilation problems can produce significant energy savings in multifamily buildings while also improving occupant comfort and health. Central ventilation system restoration is an emerging energy retrofit that has had its bumps along the way. This session explores the lessons learned from projects that encountered a variety of design and implementation problems along the way, but ultimately achieved good performance results.