Wednesday, September 24, 2008

HVAC Load Calculation Extension For AutoCAD MEP and Revit MEP

The HVAC Load Calculation Extension by Autodesk, Inc. is a commercial and industrial HVAC (Heating, Ventilation, and Air Conditioning) load calculation software package whose calculations are based upon the ASHRAE 2005 Fundamentals radiant time series (RTS) method. The purpose of this software is to provide you with total cooling and heating loads for a building so that you may properly specify the correct size HVAC equipment (whether it is a packaged rooftop unit or a boiler). This program is geared specifically toward the HVAC engineer, architect, design/build mechanical contractor, and building maintenance supervisor.

The HVAC Load Calculation Extension is available to customers of AutoCAD MEP 2009 and AutoCAD Revit MEP Suite 2009 on Autodesk Subscription and is subject to Autodesk Subscription terms and conditions.

The Extension supports sustainable design by allowing engineers to properly size HVAC equipment without oversizing. Conventional wisdom dictates that it is better to have too much cooling than not enough. Without the ability or tools to accurately calculate heating and cooling loads, oversizing equipment is a common practice. However, oversized equipment wastes a tremendous amount of energy throughout its lifetime. In a BIM-supported workflow, analysis capabilities and calculation tools (such as this Extension) enables designers and engineers to more thoroughly investigate design alternatives and optimize their emerging design for energy efficiency and sustainability.

The HVAC Load Calculation Extension uses formulas from the ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Handbook of Fundamentals. This publication compiles the fundamentals of the HVAC, such as methods for calculating peak cooling and heating loads for buildings.

The Extension produces a number of reports including: a summary load breakdown by individual room; a detailed load breakdown by individual load components such as roofs, walls, people, and lighting; and a psychrometric report that includes the properties of the entering and exiting air. Some of these reports include graphs for better visualization of the load breakdowns. Users also have the ability to export custom reports to Microsoft Word or Excel applications.

The Extension is able to import building information from AutoCAD MEP or Revit MEP using the gbXML file format. This means that all pertinent information about the building can be transferred to the Extension so that very little manual data entry is needed. Once the cooling and heating load calculations are performed, the results can be exported back to AutoCAD MEP or Revit MEP for proper duct and pipe sizing.
The HVAC Load Calculation Extension includes the following basic features:
  1. Inputs for HVAC system characteristics such as supply cooling and heating temperatures, ventilation rates, fan characteristics, cooling and heating setpoints, duct sizing, and safety factors
  2. Inputs for HVAC area (room) characteristics such as wall, window, roof, door, skylight, and partition areas. In addition, there are inputs for # of people, electrical appliances, infiltration, lighting, miscellaneous, exhaust, and plenum loads
  3. Weather data from over 800 cities throughout the world
  4. A complete u-value database for common wall, roof, window, floor, and door types
  5. A complete appliance list for determining internal electrical equipment load contributions
  6. Many reports including summary, detailed, psychrometric, wall/window breakdown, 24-hour load breakdown, and graphical reports
  7. A feature that allows the user to export all inputs and outputs to custom Microsoft Word and Excel documents
  8. Equipment selection
  9. Support for both English (IP) and Metric (SI) units


  1. How does one find HVAC equipment content for AutoCAD MEP? AutoCAD MEP is a great program and is ideal for my business. I need to have more content selection. I hope you can help.

    Thank you,

    Steve Vodicka

  2. I am looking for AutoCAD MEP HVAC, piping & plumbing content. AutoCAD MEP is the program I use for my business and would like to have more selection. Whatever you can do to help I would sure appreciate it.

    Thank you,

    Steve Vodicka

  3. ECCAD I beleive has a lot of extras for the HVAC and piping side as well as ways to send it straight to your CAM machines.