This article is a revised information sheet by the manufacturer of cold storage units regarding insulation. The bulletin allays confusion resulting from differing systems of computing the insulating effectiveness of building materials, and explains the importance of insulation quality for efficient and cost effective operation of refrigerated structures. It also explains effectiveness ratings of insulation, and offers advice for prospective buyers and present owners of walk in coolers, freezers, and refrigerated buildings. Charts list numerical equivalents of R and U values for the most common insulating materials available on the market, as well as efficiency ratings for various building materials.