Refrigerated display cases operating in supermarkets exchange heat and moisture with the store environment. ASHRAE has recently developed procedures to assess the effects of store relative humidity on display case energyrequirements. In order to evaluate the energy savings produced by reducing store relative humidity, it is necessary to know thetypical store relative humidity on an annual basis prior to its potential reduction. Eight supermarkets in the Tampa, Florida area were monitored for 12 seven-day periods betweenNovember 1997 and October 1998. Various categories of supermarkets were included and five different areas within each store were monitored. The relative humidity within thestore differed by up to 20%, and the average annual relative humidity between different stores varied by up to 12%. The annual average relative humidity of all stores was a minimumin March at 37% and a maximum in September at 56% with an average annual value for all stores of 45%. An algebraic expression was used to correlate indoor humidity ratio as afunction of outdoor humidity ratio.

Also paper CI-01-2-2, part of CI-01-2, Symposium on Aspects of Secondary Fluid Systems and Space Conditioning in Supermarkets

Units: Dual