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EnergyPlus Capabilities

According to the energyplus.net web site (as of January 2019):

"EnergyPlus is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption---for heating, cooling, ventilation, lighting and plug and process loads---and water use in buildings. Some of the notable features and capabilities of EnergyPlus include:

  • Integrated, simultaneous solution of thermal zone conditions and HVAC system response that does not assume that the HVAC system can meet zone loads and can simulate un-conditioned and under-conditioned spaces.
  • Heat balance-based solution of radiant and convective effects that produce surface temperatures, thermal comfort, and condensation calculations.
  • Sub-hourly, user-definable time steps for interaction between thermal zones and the environment; with automatically varied time steps for interactions between thermal zones and HVAC systems. These allow EnergyPlus to model systems with fast dynamics while also trading off simulation speed for precision.
  • Combined heat and mass transfer model that accounts for air movement between zones.
  • Advanced fenestration models including controllable window blinds, electrochromic glazings, and layer-by-layer heat balances that calculate solar energy absorbed by window panes.
  • Illuminance and glare calculations for reporting visual comfort and driving lighting controls.
  • Component-based HVAC that 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.
  • Standard summary and detailed output reports as well as user definable reports with selectable time-resolution from annual to sub-hourly, all with energy source multipliers."

In addition:

  • ASCII text-based weather, input, and output files that include hourly or sub-hourly environmental conditions, and standard and user definable reports, respectively.
  • Transient heat conduction through building elements such as walls, roofs, floors, etc. using conduction transfer functions.
  • Thermal comfort models based on activity, inside dry-bulb temperature, humidity, etc.
  • Anisotropic sky model for improved calculation of diffuse solar on tilted surfaces.
  • Atmospheric pollution calculations that predict CO2, SOx, NOx, CO, particulate matter, and hydrocarbon production for both on-site and remote energy conversion.
  • EnergyPlus can be used for for building load calculations and sizing equipment and uses the heat balance method recommended in the ASHRAE Handbook Fundamentals. Proper sizing of equipment without oversizing, generally saves energy as the equipment is operated nearer to optimal loads.
  • EnergyPlus runs on Windows, MacOS, and Linux computers.

Integration of Loads, Systems, and Plants: One of the strong points of EnergyPlus is the integration of all aspects of the simulation---loads, systems, and plants. System and plant output are allowed to directly impact the building thermal response rather than calculating all loads first, then simulating systems and plants. The simulation is coupled allowing the designer to more accurately investigate the effect of undersizing fans and equipment and what impact that might have on the thermal comfort of occupants within the building.