EZ Sim

Quick spreadsheet tool equivalent to sophisticated engineering analysis. EZ Sim lets you use utility bills to calibrate a simulation of a commercial facility in an interactive graphic window. Once it matches your bills, the simulation model can provide reliable estimates of potential conservation savings. The calibration process reveals how energy is used within the facility, helping diagnose why there is excessive consumption or poorly functioning building components. Potential users can review case study examples on the web site. Model also provides precision and confidence limits of savings estimates consistent with IPMVP performance verification protocol.
Use utility bills to reveal the patterns of use in your facility:

  • Diagnose energy patterns and consumption.
  • Calibrate savings estimates to agree with your actual usage.
  • Estimate energy end-uses within the facility.
  • Verify vendor claims for energy products and services.
  • Generate performance targets and compare against your utility bills./ul>


    energy accounting, utility bills, calibration, retrofit, simulation



    Expertise Required

    Basic knowledge, users should know about lighting density, U value, and types of HVAC.


    To date about 90 users in Pacific NW, supported by Northwest Energy Efficiency Alliance.


    Facility managers, resource conservation managers, utility reps, and ESCOs.


    Minimal building description (floor area, type of business, type of heating/cooling). Monthly utility bills. Can be cut-and-pasted from other applications. Weather files using mean daily temperature as proxy for all other weather variables. Can be easily updated to actual local weather. Website provides current local weather files for 250 US locations. Default building parameter values based on type of facility, but can be easily changed or updated by entry into spreadsheet windows.


    Primarily spreadsheet tables and graphs, several preformatted reports but all can be cut-and-paste into other applications.

    Computer Platform

    PC or Mac.

    Programming Language

    Excel 97and Excel 2000


    Simulation is easily tuned to match actual bills, provides performance targets to compare against post-retrofit bills--a low-cost commissioning tool. Provides precision of savings estimate (error bands) for IPMVP protocols.


    Simplified model, assumes one heating or cooling plant. Difficult to use when there are multiple plants.



    Stellar Processes, Inc.


    Suite 405
    1033 SW Yamhill
    Portland, Oregon 97205
    United States


    (503) 827-8336






    $199 for standard version, $299 for multiple-fuels version. weather files $24 each or by annual subscription.