Even now there is some sorting out to do. So the latest offerings at the 2006 International Air-Conditioning, Heating, Refrigerating Exposition (AHR Expo), had as a theme: Innovations, but never at the expense of energy savings.
A refrigeration system from Danfoss (www.acr.danfoss.com) provides self-contained direct cooling for beverage vending machines and glass door merchandisers. The units mate directly with supply and return air ducting. Chilled air is delivered directly into the cabinet duct. Return air is also direct. Units are said to be the size of a small suitcase and are stackable. According to the company, one benefit of the technology is that it is "refrigerant neutral." In this context, the company said, "This is an ideal means for cabinet builders who want to launch a new refrigerant, including CO2, at their own pace, because (the unit) does not require cabinet builders to re-engineer a refrigeration system, since engineering is done by Danfoss."