This paper is based on findings resulting from ASHRAE Research Project RP-1544.

Hot-water use in hotels and its associated energy use is significant. However, information on hotel hot-water use patterns has been limited until now, resulting in most hotel hotwater systems being designed using extremely old hot-water use data (45 to 80 years old) that predate the introduction of water and energy-efficient fixtures and appliances. In recognition of this fact, ASHRAE funded Research Project RP-1544 "Establishing Benchmark Levels and Patterns of Commercial Hot-water Use--Hotels" to both develop a monitoring methodology that could be duplicated by others to collect hot-water use data from a larger number of hotels and to obtain updated hot-water use information from at least two hotels. This paper compares hot-water use results collected for a "travel" hotel that had neither meeting rooms nor food service and a "business" hotel that had both. This paper further discusses how to normalize this information so it is useful for sizing hot-water systems for hotels with differing numbers of guest rooms than those tested. A companion paper released simultaneously with this paper describes how to use this information to select water heating systems for hotels of any desired size, and compares results of this sizing method to other hotel hot-water system sizing methods described in ASHRAE Handbook--HVAC Applications, Chapter 50, Service Water Heating, through the use of examples.