Toolkit for Building Load Calculations

Toolkit for Building Load Calculations logo.

Contains computer software and associated documentation that implements available models and algorithms for the calculation of space heat gains and losses due to all pertinent sensible and latent modes, the space conditioning load (defined as the rate of heat addition or extraction required to maintain a specified space temperature profile), and zone surface temperatures and space temperature when it is not specified. A key aspect of the Toolkit for Building Load Calculations is presenting the relationship between the heat balance algorithm (or solution technique) and the fundamental equations required to calculate zone loads and temperatures. The load-related models and algorithms contained in this Toolkit replace Energy Calculations 1 (ASHRAE 1976). Components prepared as a library of working code modules are ready for immediate implementation as stand-alone performance model or as components to be integrated with a complete building simulation program.

There are two methods of navigating the Toolkit documentation. A hierarchy of links based upon the heat balance diagram has been devised. Clicking on an area of the diagram takes the reader to the documentation and source code relating to that subject. Alternately, a traditional table of contents is available. Clicking on entries in the table of contents takes the reader to the appropriate documentation section. Screen Shots


building loads, energy calculations, heat balance model, heat transfer



Expertise Required

Student or engineer of HVAC system design and heat transfer. Moderate level of computer literacy required.


Worldwide distribution and use.


Engineers who need desktop computer models for calculation of building heat transfer and loads. The Toolkit is also of use to researchers, students & program developers of energy simulation programs.


With the permission of the Department of Energy, the Toolkit uses the input scheme, which has been developed for EnergyPlus. It is a very simple but flexible scheme that relies on a text file to provide data values, and an accompanying simple comma-delimited, text file which serves as a data dictionary to organize the values.


Output is designed around the "comma delimited" philosophy with data in ASCII format. All related data, whether test or numbers, are separated from each other by commas on a particular line. Separate lines of data are separated by carriage returns. This structure allows data to remain in ASCII format, meaning that the file structures will be simple, human readable, and portable to all computer platforms. In addition, files using a specific character such as a comma as a delimiter can be easily imported into popular spreadsheet programs.

Computer Platform

Requires a 486 or Pentium-based computer and either Microsoft windows 95 or Windows NT 3.5 or later. For Windows 95 and NT, 8MB of RAM (16MB recommended) and 10 MB of free hard-disk space is required

Programming Language

Fortran 90


The Toolkit provides a compendium of models for calculation of building heat transfer and loads so that engineers and program developers can efficiently and accurately use the available computer power to solve immediate problems. Extensive checking, testing, and validation of the algorithms and models used in the Toolkit has achieved excellent agreement with other calculation tools that use entirely different algorithms and methods.


All input data must be converted to the SI system by the Toolkit user before use.





1791 Tullie Circle, NE
Atlanta, Georgia 30329
United States


+1 (800) 527-4723 US/CAN +1 (404) 646-8400


+1 (404) 321-5478




ASHRAE's Toolkit for Building Load Calculations is available for $265 ($209 for members of ASHRAE). Order on the web at Order by phone by calling ASHRAE Customer Service at 1-800-527-4723 in the U.S. and Canada, or at (404) 636-8400 worldwide. Fax your order to (404) 321-5478. Questions about this or other ASHRAE products should be e-mailed to