Skip to Content
Find More Like This
Return to Search

SUNREL Software

An energy simulation program to aid in the design of energy-efficient residential buildings

National Renewable Energy Laboratory

Contact NREL About This Technology

Technology Marketing Summary

Historically, building performance professionals have not had reliable tools for estimating energy usage. This information deficiency has led to building upgrade and retrofit recommendations which may not be reliable or cost-effective. Scientists at the National Renewable Energy Laboratory (NREL) have designed SUNREL, an hourly energy simulation engine which precisely estimates the energy consumed by a residential building. This technology enables auditors to accurately predict energy usage and recommend economical enhancements to improve the efficiency of buildings.


SUNREL is an award-winning home energy auditing tool. Joint recipient of a 2005 R&D 100 award, SUNREL uses comprehensive thermal models to provide hourly information on energy usage. This diagnostic tool aids building performance professionals in designing energy efficient residential buildings in which the energy consumption depends predominantly on interactions between the building, its occupants, and the localized environment.

SUNREL outstrips competitor software as a simple-to-use tool which is robust and thoroughly tested. With over a decade of use, it fully complies with the Home Energy Rating System Building Energy Simulation Test for typical houses with or without passive solar design elements. SUNREL incorporates data on the weather, natural ventilation, window glazings and shading, solar radiation, Trombe walls, lights, fans, and other appliances to compute efficiency and heating or cooling requirements. SUNREL has been proven to be a successful and useful residential thermal energy performance tool.

  • Easy to use energy analysis tool
  • Robust due to over a decade of use and testing
  • Allows users to choose durable, practical, and effective energy-saving options
  • Developed for passive solar design buildings
Applications and Industries

Energy efficiency planning and testing for builders, contractors, retrofitters, sustainability consultants, energy auditors, or researchers

More Information

The SUNREL copyright and trademark are owned by the Alliance for Sustainable Energy, LLC, courtesy of the U.S. Department of Energy.

Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
SWR-99-42 and SWR-99-43Development - Algorithm development, coding, and initial user interface are complete. Ongoing improvements include additional algorithms to model the operations of HVAC system heating and cooling equipment.Available - Currently this software is available for non-commercial use on the NREL website, Please contact the NREL Commercialization and Technology Transfer Office for information concerning a commercial license to use the software. 07/14/201007/28/2010

Contact NREL About This Technology

To: Jean Schulte<>