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DISCLAIMER: Unless specifically noted at the beginning of the article, the content, calculations, and opinions expressed by the author(s) of any article in Insulation Outlook are those of the author(s) and do not necessarily reflect the views of NIA. The appearance of an article, advertisements, and/or product or service information in Insulation Outlook does not constitute an endorsement of such products or services by NIA. The information is provided as a reference service only, and no claims for technical accuracy can be guaranteed. Material may have become outdated since publication. The user may want to verify the technical accuracy prior to use of this information. The article may not be reproduced in any means, in whole or in part, without the prior written permission of the publisher and NIA. To reprint this information, contact the NIA offices.

New Calculators Help You Answer Mechanical Insulation Questions

By Ronald L. King

The Mechanical Insulation Design Guide (MIDG) hosts three new simple calculators: two Energy Loss, Emission Reduction, Surface Temperature, and Annual Return Calculators and the Financial Calculator. The new calculators join the Time to Freezing for Fluid in an Insulated Pipe, Temperature Drop, Simple Heat Flow, and Simple Thickness calculators.

This suite of Mechanical Insulation Assessment and Design Tools were developed under the umbrella of the U.S. Department of Energy's Industrial Technologies Program's (DOE-ITP's) Mechanical Insulation Education and Awareness Campaign (MIC) to make common calculations in the design and analysis of mechanical insulation systems quicker and easier. The browser-based calculators do not require any software to be installed, the results page for each calculation can be printed, and they are free to all users.

The calculators are designed for use by:

  • Corporate executive management
  • Design professionals (general, mechanical, and process engineers and contractors)
  • Energy and environmental consultants and/or service companies
  • Facility owners and managers (across all industry segments)
  • Federal, state, and local energy and environmental offices
  • Heating, ventilating, and air-conditioning designers and contractors
  • Maintenance managers and coordinators
  • Engineering educators
  • Mechanical insulation industry participants (manufacturers, distributors, contractors, etc.)
  • Refrigeration designers and contractors
  • Utilities/energy supply companies (all types).

All the calculators now have a single, easily accessible page on MIDG: There are also links to them in relevant sections of the Design Objectives text. The calculators are also available on the DOE-ITP's Software Tools website at Specific calculator URLs are given below.

Energy Loss, Emission Reduction, Surface Temperature, and Annual Return Calculators

These calculators, one for equipment (vertical flat surfaces) and one for horizontal pipe applications, estimate the performance of an insulated system given the operating temperature, the ambient temperature, and other details about the system. They help illustrate the relationships between energy, economics, and emissions for insulated systems.

The Equipment Spreadsheet ( estimates the heat flows through a vertical flat steel surface (typical of the sides of a large steel tank containing a heated or cooled fluid). Information concerning a hypothetical insulation system (e.g., the area, operating temperature, ambient temperature and wind speed, insulation material, and surface emittance of a proposed insulation system) may be input by the user.

The Pipe Spreadsheet ( estimates the heat flows through horizontal piping. Information concerning a hypothetical insulation system (e.g., the length of run, pipe size, operating temperature, ambient temperature and wind speed, insulation material, and surface emittance of a proposed insulation system) may be input by the user.

Users will need to input:

  • Surface area in square feet for equipment or length of piping and pipe size
  • Operating temperature in °F
  • Ambient temperature in °F
  • Wind speed in mph (guidance provided with calculator)
  • Insulation type (calculators provide for a selection of five major types)
  • Insulation installed cost (calculators provide typical values)
  • Emittance of surface (guidance provided with calculator)
  • Expected useful life of the insulation system in years
  • Operating hours per year
  • Efficiency of fuel conversion as a percentage (guidance provided with calculator)
  • Fuel type and cost (calculators provide for a selection of five major types and typical cost for each).

Based on input, calculators will provide the following by thickness, in inches, of insulation:

  • Surface temperature in °F
  • Heat loss in Btu/hr
  • Cost of fuel in dollars per year
  • Installed insulation cost (estimated)
  • Payback in months
  • Annual return as a percentage (Simple IRR)
  • CO2 emissions in Metric Tonnes/year.

Financial Calculator

This calculator ( was developed to provide a convenient way to estimate the financial returns related to investments in mechanical insulation: Simple Payback in years, Internal Rate of Return (IRR or ROI), Net Present Value (NPV), and annual and cumulative Cash Flow. It can be used for an overall mechanical insulation project or for a small mechanical insulation investment such as insulating a valve or replacing a section of insulation.

Users will need to input:

  • Initial cost of the investment in dollars
  • First year energy savings in dollars per year
  • Energy cost escalation rate as a percent per year
  • Estimated economic life in years
  • Discount rate as a percentage.

Based on input, the calculator will provide:

  • Simple payback period in years
  • Internal rate of return (IRR or ROI) as a percentage
  • Net Present Value (NPV) in dollars
  • Annual and cumulative cash flows.

Time to Freezing for Fluid in an Insulated Pipe Calculator

This calculator ( estimates the time for a long, fluid-filled pipe (no flow) to reach the freezing temperature.

It is important to recognize that insulation retards heat flow; it does not stop it completely. If the surrounding air temperature remains low enough for an extended period, insulation cannot prevent freezing of still water or of water flowing at a rate insufficient for the available heat content to offset heat loss. Well-insulated pipes, however, may greatly extend the time to freezing.

Users will need to input:

  • Initial temperature of fluid in °F
  • Freezing temperature of fluid in °F
  • Ambient temperature in °F
  • Density of fluid, pcf (guidance provided)
  • Specific heat of fluid in Btu/(lbm·°F) (guidance provided)
  • Inside diameter of pipe and insulation in inches (guidance provided)
  • Outside diameter of insulation in inches (guidance provided)
  • Thermal conductivity (k) of insulation (guidance provided).

Based on input, the calculator will provide the estimated time to freeze point in hours.

Temperature Drop Calculator

This calculator ( estimates the temperature drop (or rise) of a fluid flowing in a duct or pipe.

An example is the use of insulation to minimize temperature change (either temperature drop or rise) of a process fluid from one location to another (e.g., a hot fluid flowing down a pipe or duct).

Users will need to input:

  • Entering fluid temperature in °F
  • Ambient temperature in °F
  • Flow rate of fluid in lbm/h
  • Specific heat of fluid in Btu/lbm·°F (guidance provided)
  • Length of pipe or duct run in feet
  • Outside perimeter of pipe or duct, including insulation, in feet
  • Overall heat transfer coefficient in Btu/h·ft²·°F.

Based on input, the calculator will provide:

  • Temperature drop
  • Leaving fluid temperature.

Simple Heat Flow Calculator

This calculator ( estimates the heat flow through an insulation for flat or cylindrical systems given the temperatures on each side and the effective conductivity of the insulation material.

Users will need to input:

  • Temperature of hot and cold surface in °F
  • Conductivity of material, Btu-in./(hr·ft²·°F)
  • Area for flat geometry in square feet
  • Thickness for flat geometry in inches
  • Area for cylindrical geometry (outer surface) in square feet
  • Inner and outer radius for cylindrical geometry in inches.

Based on input, the calculator will provide the heat flow in Btu/hr.

Controlling Surface Temperature with Insulation Calculator

This calculator ( estimates the thickness of insulation required to obtain a specified surface temperature given the boundary temperatures, the conductivity of the insulation material, and the surface coefficient.

Users will need to input:

  • Operating temperature in °F
  • Ambient temperature in °F
  • Surface temperature in °F
  • Effective conductivity of insulation, Btu-in./(hr·ft²·°F)
  • Surface coefficient in Btu/(hr·ft²·°F).

Based on input, the calculator will provide the calculated thickness of insulation in inches.

What's Next

The calculators were developed as part of a larger effort by the DOE-ITP to improve the energy efficiency of the U.S. industrial and commercial sectors. Project Performance Corporation and the National Insulation Association, in conjunction with its alliance with the International Association of Heat and Frost Insulators and Allied Workers, are working with the DOE-ITP to design, implement, and execute the MIC, a program to increase awareness of the energy efficiency, emission reduction, economic stimulus, and other benefits of mechanical insulation in the industrial and commercial markets. It was created to:

  • Educate industry about and promote the benefits of mechanical insulation by providing practical data and case studies outlining potential energy savings provided by mechanical insulation installation; and
  • Launch an aggressive public education and awareness campaign to combat climate change and improve energy efficiency.

As a further step in this effort, the MIC is also planning to develop applications (apps) for hand-held mobile devices that will enable users to access these calculators in the field. Other initiatives in the MIC include developing a series of e-learning modules and guest lectures. For more information about MIC and the Mechanical Insulation Marketing Initiative, visit

This article appeared in the February 2011 issue of Insulation Outlook.

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Ronald L. King

Ron King is a NIA Past President and Consultant. He was awarded NIA’s President’s Award in 1986 and again in 2001. He is a 50-year veteran of the commercial and industrial insulation industry who has held executive management positions at an accessory manufacturer and specialty insulation contractor. He retired (2004) as Chairman, Chief Executive Officer, and President of a large national insulation distributor/fabricator. Mr. King currently serves as a consultant to NIA on a variety of educational, outreach, and governmental initiatives, including coordinating allied association alliance-partnership activities. He has served as Chairman of both the National Institute of Building Sciences’ National Mechanical Insulation Committee and the Consultative Council. He also serves as NIA’s liaison to the Federation of European Insulation Societies, which represents the European mechanical insulation market. He can be reached at 281-360-3438 or

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