It is the author's opinion that the engineering design community is on the verge of a major shift in its ventilation air delivery and mechanical system design paradigm. This article presents the reasons that engineers are seriously considering dedicated outdoor air systems, and what the new paradigm will likely be.
Most of the current anxiety over refrigerant selection is unwarranted. Engineers, owners, and others involved should revert to traditional chiller specifications based on cost, performance, local manufacturer support, service options, and reliability. Anticipating more stringent environmental regulations, they also should take all practical steps to reduce refrigerant releases and increase efficiency.
Wood structures are highly susceptible to rapidly spreading fire, and George Washington's mansion at Mount Vernon is all wood, much of it original. Equally effective and unobtrusive fire detection and protection measures are now in place and continually upgraded to safeguard the historic mansion, its contents, and its visitors and staff.