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3E Plus Program Overview

  • Determines economic thickness of insulations based on return on investment for chosen fuel cost, installed cost, tax rates, maintenance, etc.
  • Calculates the amount of insulation needed for personnel protection for various design conditions.
  • Calculates the thickness of insulation needed for condensation control.
  • Calculates greenhouse gas emissions and reductions.
  • Determines surface temperature and heat loss/gain calculations of individual insulation thickness up to 10 inches (250 mm).
  • Solves for outside insulated surface temperatures for all types of insulation applications at different process temperatures and various configurations.
  • Calculates bare vs. insulated heat loss efficiency percentages for horizontal and vertical piping, ducts and flat surfaces.
  • Performs calculations for various flat surfaces, selected pipe sizes and all standard iron pipe sizes from 1/2" to 48" (15 - 1200 mm).
  • Calculates heat loss/gain and outside insulated surface temperatures for any insulation material provided the thermal conductivity, associated mean temperatures, and temperature limit are entered by the user.

3E Plus® Program Details

  • 3E Plus version 4.1 operates in Windows® XP, Vista and Windows 7 environments.
  • Provides simple payback calculations
  • Customized program details such as insulation materials, jacketing, fuel types and base metals can now be saved and easily imported when updating the program (4.1)
  • Can easily export insulation audit data to an Excel spreadsheet
  • Performs calculations for most types of insulation materials and accepts performance data provided by the user for other materials.
  • Provides calculations for many fuel types and five different surface orientations. User can add own fuel combinations.
  • Uses calculations and default values from independent sources. Contains updated methodology from the most recent version of ASTM C 680 Standard Practices for Determination of Heat Gain or Loss and the Surface Temperature of Insulation Piping on Equipment Systems by the Use of a Computer System.
  • Allows user to customize program by adding and saving individual company's insulation installed cost estimates.
  • Has all the latest thermal curves contained in the ASTM material standards.
  • Automatically calculates thickness tables.
  • Calculates in both metric and inch-pound units.
  • Updated thermal curves and new insulation materials

Calculation Features

3E Plus® can perform a wide range of calculations including:


  • The thermal performance of both insulated and uninsulated piping and equipment.
  • The energy (Btu) currently being saved with existing insulation systems and the actual dollar value of those savings.
  • The potential Btu savings with an insulation upgrade.


  • Note in 3E Plus version 4.1, all calculations involving money or economics are in the Economics section of the program.
  • Cost of energy
  • Simple payback
  • Economic thickness
  • The cost of operating systems with existing insulation in terms of Btu and dollars.
  • The potential cost reduction of operating those same systems with an insulation upgrade.


  • The number of pounds (or metric tonnes) of greenhouse gases [CO2, NOx] currently being prevented from release into the atmosphere due to reduced fuel consumption resulting from greater insulation thickness.
  • The potential number of pounds of greenhouse gases that could be prevented from release into the atmosphere through an insulation upgrade, resulting from greater reductions in fuel consumption.

Click here to download
3E Plus User Guide
(2.7 Mb PDF)


The latest 3E Plus Program Software can be downloaded for free after a simple registration process!

Program History of 3E Plus®

3E Plus® was developed by the North American Insulation Manufacturers Association (NAIMA) to simplify the task of determining how much insulation is necessary to use less energy, reduce plant emissions and improve process efficiency.

1961 — First version of Economic Thickness for Industrial Insulation program developed as a card deck.

1973 — Next version of card deck called Econ 1.

1980 — Card deck converted to MS-DOS and called Economic Thickness for Industrial Insulation for Hot and Cold Surfaces, covering economics and payback.

Late 1980s — Environmental aspect added to the program now called 3E Version 1.0.

1993 — 3E Version 2.0 released.

1994 — “Plus” added to program name to connote performance of insulation in place. 3E Plus® also included a heat flow program.

1996 — 3E Plus® honored with US Dept. of Energy National Awards for Energy Efficiency and Renewable Energy.

1998 — 3E Plus® Version 2.1 released.

2001 — 3E Plus® Version 3.0 released. This was the first Windows version of the program and CO2 numbers were added.

2002 — 3E Plus® Version 3.1 released.

2005 — 3E Plus® Version 4.0 released. Close to 10,000 registered users.

2012 — 3E Plus v 4.1 released. Operates on Windows® XP, Vista and Windows 7. Over 15,000 registered users.

3E Plus® is a registered trademark of the North American Insulation Manufacturers Association (NAIMA)