Underfloor air-distribution (UFAD) systems have been designed and built in the United States for more than 20 years with various degrees of success. The system remains controversial, with both advocates and detractors, but has experienced significant penetration in some markets. The most common complaint with these systems, however, is that spaces are chronically over-cooled. Many critical factors have been identified for avoiding this pitfall, but the implementation of effective control strategies is arguably the most important step.