Building Energy Software Tools
Formerly hosted by US Dept. of Energy    


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Easy to use detailed energy simulation program which performs hourly calculations to estimate annual energy usage for heating, cooling and water heating in residential buildings. In addition to its purpose as a compliance tool for California�s Title 24 Energy Efficiency Standards, Micropas can be used to demonstrate that a home meets Energy Star requirements in California (15% above Title 24). The program includes a load calculation for use in sizing heating and cooling equipment.

 Micropas6 has been in wide use in California since the early 1980s as a building energy code compliance tool and is growing in use elsewhere under the Model Energy Code. The last survey showed that about 75% of the single-family homes permitted in California used Micropas to determine code compliance. The program is mature, reliable and fast. Micropas6 is fully supported with top notch documentation and complete printouts. The program has a wide range of features to help automate and manage its use.

Expertise Required: 

to read building plans and an understanding of how the energy efficiency of building features (e.g. U-factors, SHGC, R-values, SEER, etc.) are specified.


Although Micropas is a capable general purpose hourly simulation program for energy efficient residential buildings, the main use of the program is to document compliance with residential building energy codes such as the Model Energy Code and California's Title-24 Code.


Data is required describing each building thermal zone (15 maximum); opaque surfaces (walls, roofs, floors, 100 maximum); fenestration products (doors, windows, skylights, 100 maximum); thermal mass (slabs, etc., 25 maximum); HVAC equipment (heating, cooling, venting, thermostats) and water heating systems (domestic and hydronic heating).


Seven types of clearly formatted printouts are available including summary output, detailed building descriptions, HVAC sizing summary and assembly U-value calculations. For detailed oriented studies, yearly, monthly, daily and hourly table output is available including time-of-use and bin data. Annual and table outputs can be saved in delimited formats suitable for importing into other software for additional analysis and graphics. For studies including many runs, a parametric run generator and databases of run results are available.


Mature and reliable program used daily by hundreds of energy consultants in California. Good documentation and good support via toll free number. Can calculate annual energy usage and provide load (sizing) calculations at the same time. Able to manage multiple runs. Not as complex as DOE-2, not as simple minded as UA type compliance programs.

United States
Major Capabilities: 
Last Software Update: 
30 June 2010
Last Entry Update: 
04 October 2015
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