Project Website:
-- Lawrence Berkeley National Lab (LBNL) – Berkeley, CA
-- Anyhere Software – Berkeley, CA
-- National Renewable Energy Lab (NREL) – Golden, CO
Partner: Bonneville Power Administration – Portland, OR
DOE Funding: $300,000 in FY19; $3,315,000 to date (2010 - present)
Project Term: 1985 - present
Funding Opportunity: Emerging Technologies core funding
Related Projects: OpenStudio, Fenestration Tools

Project Objective

Radiance is a free and open-source lighting engine that is used extensively by engineering firms for innovative solar control, lighting, and daylighting design to improve the energy efficiency of buildings. Radiance offers complete flexibility in terms of scene geometry and materials and has been validated using detailed measurements. In recent years, new Radiance developments have resulted in the capability to conduct an annual simulation in less than two minutes and significant improvements in accuracy when modeling anisotropic, light-scattering systems and materials that are common to many shading and daylighting devices. 

In FY19, Radiance is being enhanced to support fast and accurate annual simulation for complex fenestration systems (CFS) including both co-planar and non-coplanar shading systems. This work involves detailed measurement, algorithm development, and validation using test facilities. 

Radiance rendering of daylighting and electric lighting for the retrofit of the New York Times offices in New York.

Andrew McNeil, LBNL.

Project Impact

Radiance is the most widely used engine in lighting, daylighting, and solar control design and is embedded in a number of free and commercial architectural-engineering design applications including IES Virtual Environment, Design Builder, and Sefaira Architecture. A dynamic listing of applications that use Radiance is hosted by the IBPSA building energy software tools directory.  

In addition to architects and engineers, Radiance is also used by fenestration, shading, daylighting, and lighting manufacturers to develop and optimize both new and existing lighting, daylighting, and solar control products, allowing designers to simulate the performance of a wide range of fenestration systems.

Radiance is embedded in a large and growing number of public- and private-sector tools.
Radiance is embedded in a large and growing number of public- and private-sector tools.


DOE Technology Manager: Amir Roth
Principal Investigator: Eleanor Lee, LBNL

Publications and Presentations