Posted August 8, 2023

Version 6.2 of Building Efficiency System Tool (BEST) Now Available for Download

Interactive commercial building HVAC system efficiency comparison app helps builders choose the most efficient systems for their projects. 

Version 6.2 of the Radiant Professionals Alliance’s (RPA) Building Efficiency System Tool™ (BEST), an interactive commercial building HVAC system efficiency comparison application, is now available for download at

The enhanced BEST 6.2 focuses attention on energy use, including up to four selected systems in one life-cycle comparison report that utilizes historical design temperatures to determine peak energy demand and the energy utilization index (EUI).

The latest version of BEST addresses the challenge of sustainability and decarbonization tactics to use less energy. The application helps identify the choices clearly by utilizing data from projects throughout the United States. BEST 6.2 now includes up to 10 building types per 1,000 U.S.-based locations, based on weather, load and utility rates provided by trusted sources.

“Our industry is changing rapidly and utilizing digital modeling tools can help us to make informed decisions about building systems and the options we have,” said John A. Mullen, technical liaison to the Radiant Professionals Alliance and director of technical services and research with The IAPMO Group.

BEST 6.2 includes a Demand Energy Efficiency Ratio (DEER) tab that makes it easier than ever to compare energy demand to existing efficiency ratings.

“When you use BEST software for system design, you get a side-by-side comparison of up to four system types,” said Greg Cunniff, head of Application Engineering for the Hydronics Industry Alliance (HIA), the RPA committee responsible for the development of BEST. “This free tool can help determine the return on investment for building owners who looking to have the most efficient building on the block or benchmark their current use for long-range capital planning.”

Upon its introduction in 2016, BEST solved a long-standing industry issue of being able to accurately compare different styles of HVAC systems, which are all tested to different standards, with various efficiency ratings (EER, IEER, SEER, COP, HSPF), as they are applied in an actual building.

To learn more about the HIA and the RPA, or to join this important efficiency advocacy effort, visit and Please contact John Mullen at or (631) 994-4774 for any questions on the RPA and the BEST software.