Brennan Less

Brennan Less

Technology Researcher III


Brennan Lesshas spent nine years as a building science researcher at Lawrence Berkeley National Laboratory in the Residential Building Systems group and the Indoor Environment group. His current work focuses on state-of-the-art field measurements and simulations of smart ventilation systems, hygrothermal performance of sealed and insulated attics, indoor air quality, deep energy retrofits, zero net energy homes, and the health-energy efficiency nexus. He regularly presents his work at national conferences for the home performance and IAQ industries, and he is the author of over 20 research reports and technical journal articles. Brennan holds a Master of Science in Architecture degree from UC Berkeley – California (2012). He also has extensive experience as a home energy auditor and in residential construction and brings this hands-on approach to his research activities. 


Spot: Multifamily Building Efficiency Screening Tool Team -  October 31st 2023

Rapid development of the comprehensive and easy to use Multifamily Building Efficiency Screening Tool for HUD.

HUD MBEST Tool Development -  May 25th 2023

A team of BTUS researchers created the Multifamily Building Efficiency Screening Tool (MBEST) for HUD's Green and Resilient Retrofit Program (GRRP) []. The GRRP covers grants and loans of almost $5 billion of investment in multifamily housing. The tool will be used to screen multifamily buildings and understand current opportunities for energy efficiency improvements.  The tool allows building managers and owners to enter information about lighting, HVAC heating/cooling systems, domestic hot water systems, and the building envelope to come up with a building score that allows HUD to make decisions about investing in building upgrades. The key reason for this SPOT nomination is that the LBNL team worked under considerable time pressure to create the tool in just a few weeks to meet HUDs deadline for launching the program and utilized their expertise and knowledge over a broad range of multifamily building performance to make the tool both comprehensive and easy to use. 

Spot: Brennan Less -  January 23rd 2020

Leading the Smart Ventilation for Advanced California Homes project to a successful conclusion.

Societal Impact Award -  October 4th 2019

2019 Societal Impact

Citation: In recognition of the Residential Ventilation Team’s scientific research and development of technologies, practices, and standards for residential ventilation that have made millions of homes healthier and more comfortable.