Location tab on model data at Site level
The Water Mains Temperature data is used to calculate water temperatures delivered by underground water main pipes. The mains temperatures are used as default, make-up water temperature inputs for the Water heater. The mains temperatures are also used in the water systems objects to model the temperature of cold water supplies.
Note: This data is only used when using Detailed HVAC. For Simple HVAC a single annual average mains water temperature is defined under the DHW header on the HVAC tab.
Water mains temperatures are a function of outdoor climate conditions and vary with time of year. A correlation has been formulated to predict water mains temperatures based on two weather inputs:
These values can be easily calculated from annual weather data using a spreadsheet or from the ".stat" file available with the EnergyPlus weather files at www.energyplus.gov. Monthly statistics for dry-bulb temperatures are shown with daily averages. The daily averages are averaged to obtain the annual average. The maximum and minimum daily average are subtracted to obtain the maximum difference. For more information on the water mains temperatures correlation, see the EnergyPlus Engineering Document.
Alternatively, the water mains temperatures can come from a schedule. This is useful for measured data or when water comes from a source other than buried pipes, e.g., a river or lake.
Select from the options:
If the Calculation method is 1-Schedule, the water mains temperatures are read from the schedule referenced by this field. Note that the schedule temperatures must be in °C even when using IP units.
If the Calculation method is 2-Correlation, this field is used in the calculation as the annual average outdoor dry-bulb air temperature (in °C or °F).
If the calculation method is 2-Correlation, this field is used in the calculation as the maximum difference in monthly average outdoor air temperatures (in Δ°K or Δ°F).