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

EnergyPlus

Ratings
4.75
Reviews 0

EnergyPlus is DOE's whole-building energy simulation engine. EnergyPlus includes advanced simulation features including sub-hourly time steps, simultaneous solution of zone conditions and HVAC system actions, a modular HVAC structure that accommodates a wide range of system configurations, and a runtime scripting language for user-defined control strategies.

Originally released in 2001, EnergyPlus is continually updated—major updates are released twice a year—and fully documented and supported. EnergyPlus is open source software. It forms the analytical basis for energy-efficiency standards such as ASHRAE 90.1 and for both free and commercial energy analysis products. Version 8.4.0 was released 9/30/2015. Learn more at energyplus.net.

Expertise Required: 

Building physics or mechanical engineering background is helpful.

Audience: 

Mechanical, energy, architectural, and control engineers, building auditors and operators, building product designers, energy-efficiency program administrators and portfolio managers, energy-efficiency policy analysts, researchers.

Input: 

EnergyPlus is a console-based program that takes inputs—both building description and weather—as structured ASCII text files. EnergyPlus comes with IDF-Editor, a grid-based wizard that facilitates the creation of simple models and performs input-consistency checks. A number of comprehensive graphical user interfaces are also available (http://energyplus.net/interfaces/).

Note: EnergyPlus building descriptions use a custom object-oriented format. DOE is currently developing a complementary format that uses the standard object-oriented JSON language. This new format will hopefully be available in the Fall 2016 release.

Output: 

EnergyPlus produces both summary and detailed output in unstructured text, CSV, HTML, and SQLite formats. As is the case with input, EnergyPlus comes with a simple output visualization utility, EP-Compare. The above mentioned user interfaces also graphically display EnergyPlus output.

Note: DOE is also currently developing a JSON-based output format that references the JSON-based input. This output option will hopefully be available in the Fall 2016 release.

Strengths: 

EnergyPlus implements detailed building physics algorithms for heat transfer—radiation, convection, and conduction—air and moisture transfer, light distribution, and water flows. These allow EnergyPlus to model a broad range of of building and mechanical system configurations and conditions. EnergyPlus' list of advanced features includes:

  • Integrated simultaneous solution of thermal zone conditions and HVAC system response that does not assume that the HVAC system can meet zone loads.
  • Automatically varied time steps for interactions between thermal zones and HVAC systems that can model systems with fast dynamics.
  • Heat balance-based solution of radiant and convective effects that produce accurate surface temperatures for calculating condensation and thermal comfort.
  • Combined heat and mass transfer model that accounts for air movement between zones..
  • Illuminance and glare calculations for reporting visual comfort and driving lighting controls.
  • Component-based HVAC that flexibly supports both standard and novel system configurations.
  • A large number of built-in HVAC and lighting control strategies and an extensible runtime scripting system for user-defined control.
  • Functional Mockup Interface import and export for co-simulation with other engines.

Other strengths include an open-source license and committed support from DOE.

Country: 
United States
Major Capabilities: 
Whole-building Energy Simulation
HVAC System Selection and Sizing
Code Compliance
Building Type: 
Commercial
Residential
Keywords: 
EnergyPlus
Language: 
English
Platform: 
Linux
Windows
Mac OS X
Pricing: 
Free
Help and Support: 
Free Email Support
Third Party Support
Last Software Update: 
30 September 2017
Last Entry Update: 
18 July 2018
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