Energy Calculator for Horizontal Piping  

by the National Mechanical Insulation Committee (NMIC)


This calculator estimates the performance of an insulated horizontal piping system given the operating temperature, the ambient temperature, and other details about the system.


  • Line 1. Enter the length of the piping run in linear feet
  • Line 2. Select Nominal Pipe Size, NPS
  • Line 3. Enter average operating (process) temperature for the period of operation
  • Line 4. Enter average ambient temperature for the period of operation
  • Line 5. Enter average wind speed for the period of operation (if unknown, use 1 mph for indoor, 8 mph for outdoor)
  • Line 6. Select an insulation material. Note: Calculator does not screen for material temperature limitations - Use caution.
  • Line 7. Enter a cost multiplier to modify the default installed costs (e.g. enter 1.10 to increase costs 10%)
  • Line 8. Enter the effective emittance of the exterior surface (see MIDG>Design Data>Table 1 for guidance)
  • Line 9. Enter the expected life of the insulation system in years
  • Line 10. Enter the number of hours per year of system operation (e.g. 8760 for full year operation)
  • Line 11. Enter the conversion efficiency of the system in percent

    Typical conversion efficiencies for various systems are:
    Fossil fuel boilers (Non-condensing)    65 - 85%
    Fossil fuel boilers (Condensing) 80 - 95%
    Electric resistance boilers 92 - 96%
    Electrically operated chillers 300 - 700%
    Absorption chillers 60 - 100%
  • Line 12. Select the fuel used
  • Line 13. Enter cost of fuel if known or use default value


  • One dimensional, steady state heat transfer
  • Base structure is a horizontal steel pipe
  • Thermal conductivity based on ASTM Specification Values
  • Installed costs of insulation are from industry sources and represent single layer installations
  • Installed costs include aluminum jacketing but do not include vapor retarders or vapor sealing
  • Fuel content, emissions and typical fuel costs are from U.S. Energy Information Administration
  • Emissions are in Metric Tonne per year (MT/yr)and are are assumed to be at the facility (except for electricity which are are at the power plant)

Note: NA means Not Available