HVAC has come a long way. Designers have been con stantly working to improve the system design on various fronts. Efficiency, energy management, in- door air quality, controls, noise re- duction, compactness, economics, and environmental impact, have been the key drivers pushing the designer to deliver better and more. All the innovations and design im- provements have been built around the "traditional approach" with the cooling coil as our main tool in controlling both temperature and moisture (for cooling and dehu- midification) in the conditioned space. System designs have moved to providing better indoor air qual- ity by increasing and having the right mix of re-circulated and out- side air, but some questions remain unanswered.