Brennan Less

Brennan Less

Brennan is a buildings researcher at the Lawrence Berkeley National Lab (LBNL) in the Residential Building Systems group and the Indoor Environment group. He manages all aspects of research projects in energy, ventilation and IAQ in new and existing homes. He is experienced in research design, metering and sensors, statistical computing and programming, building simulation, and construction, inspection and testing of buildings. He presents his work at national conferences for the home performance and IAQ industries, and he is the author of numerous 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.

Contact Information

Phone: 510-410-4036

Awards

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) [https://www.hud.gov/grrp/leadingedge]. 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.

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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.

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Publications

2024

The Impact of Simplified Window and Exhaust Fan Assumptions on Model- Based Predictions of Inter-Zonal Air Flow and Contaminant Transport in Multifamily Buildings

Authors: Walker, Iain S; Brennan Less; Nuria Casquero-Modrego; Cara Lozinsky, and Michael D Sohn.
10/2024

Reducing the Cost of Home Energy Upgrades in the US: An Industry Survey

Authors: Satre-Meloy, Aven; Nuria Casquero-Modrego; Iain S Walker, and Brennan Less.
10/2024

Electrical Service Panel Capacity in California Households with Insights for Equitable Building Electrification

Authors: Less, Brennan; Iain S Walker; Sean Murphy, and Eric Fournier.
08/2024

HVAC Heat Pump Upgrades and their Impact on Household Maximum Power Demand

Authors: Less, Brennan, and Iain S Walker.
08/2024

Compartmentalization and Ventilation System Impacts on Air and Contaminant Transport for Multifamily Buildings

Authors: Walker, Iain S; Brennan Less; Cara Lozinsky; David M Lorenzetti; Nuria Casquero-Modrego, and Michael D Sohn.
03/2024

2023

Quantifying the Potential Health Impacts of Unvented Combustion in Homes – A Meta-Analysis

Authors: de Mesquita, P. Jacob Bueno; Nuria Casquero-Modrego; Iain S Walker; Brennan Less, and Brett C Singer.
10/2023

Challenges and Opportunities for Home Decarbonization

Authors: Walker, Iain S; Nuria Casquero-Modrego, and Brennan Less.
03/2023

2022

Getting to Scale for Decarbonizing Homes in the US: An Industry Survey

Authors: Casquero-Modrego, Nuria; WR Chan; Brennan Less, and Iain S Walker.
11/2022

Compartmentalization and Ventilation System Impacts on Air and Contaminant Transport for a Multifamily Building

Authors: Walker, Iain S; Brennan Less; David M Lorenzetti; Michael D Sohn, and Nuria Casquero-Modrego.
08/2022

Home Energy Upgrades as a Pathway to Home Decarbonization in the US: A Literature Review

Authors: Less, Brennan; Nuria Casquero-Modrego, and Iain S Walker.
07/2022

The Costs of Home Decarbonization in the US

Authors: Walker, Iain S; Brennan Less; Nuria Casquero-Modrego, and Leo I Rainer.
06/2022

Pathways to Home Decarbonization

Authors: Walker, Iain S; Brennan Less, and Nuria Casquero-Modrego.
06/2022

Simulation-Based Analysis of Impacts of Reduced Envelope and Duct Air Leakage on Indoor Air Pollutant Concentrations in Occupied Manufactured Homes

Authors: Delp, William W; Brennan Less; Haoran Zhao; Spencer M Dutton; Wanyu R Chan, and Brett C Singer.
06/2022

Analysis of Zoned Residential Ventilation Systems

Authors: Walker, Iain S; Brennan Less; David M Lorenzetti, and Michael D Sohn.
05/2022

A Time-Varying Model for Predicting Formaldehyde Emission Rates in Homes

Authors: Zhao, Haoran; Iain S Walker; Michael D Sohn, and Brennan Less.
05/2022

Carbon and Energy Cost Impacts of Electrification of Space Heating with Heat Pumps in the US

Authors: Walker, Iain S; Brennan Less, and Nuria Casquero-Modrego.
01/2022

2021

Development of Advanced Smart Ventilation Controls for Residential Applications

Authors: Walker, Iain S; Brennan Less; David M Lorenzetti, and Michael D Sohn.
08/2021

Emerging Pathways to Upgrade the US Housing Stock: A Review of the Home Energy Upgrade Literature

Authors: Less, Brennan; Iain S Walker, and Nuria Casquero-Modrego.
04/2021

DOE Deep Energy Retrofit Cost Survey

Authors: Chan, Wanyu R; Brennan Less, and Iain S Walker.
01/2021

The Cost of Decarbonization and Energy Upgrade Retrofits for US Homes

Authors: Less, Brennan; Iain S Walker; Nuria Casquero-Modrego, and Leo I Rainer.

2020

Smart Ventilation for Advanced California Homes

Authors: Less, Brennan; Iain S Walker; David M Lorenzetti; Evan Mills; Vi H Rapp; Spencer M Dutton; Michael D Sohn; Xiwang Li; Jordan D Clark, and Max H Sherman.
06/2020

Assessment of peak power demand reduction available via modulation of building ventilation systems

Authors: Young, Matthew; Brennan Less; Spencer M Dutton; Iain S Walker; Max H Sherman, and Jordan D Clark.

Measured Moisture Performance of Sealed and Insulated Attics with Permeable Insulation In California Homes

Authors: Walker, Iain S, and Brennan Less.

2019

Energy savings with outdoor temperature-based smart ventilation control strategies in advanced California homes

Authors: Less, Brennan; Spencer M Dutton; Iain S Walker; Max H Sherman, and Jordan D Clark.
04/2019

Sealed and Insulated Attic Hygrothermal Performance in New California Homes Using Vapor and Air Permeable Insulation—Field Study and Simulations

Authors: Less, Brennan; Iain S Walker; Jonathan L Slack; Leo I Rainer, and Ronnen M Levinson.
04/2019

Efficacy of occupancy-based smart ventilation control strategies in energy-efficient homes in the United States

Authors: Clark, Jordan D; Brennan Less; Spencer M Dutton; Iain S Walker, and Max H Sherman.
03/2019

Ventilation and Indoor Air Quality in New California Homes with Gas Appliances and Mechanical Ventilation

Authors: Chan, Wanyu R; Yang-Seon Kim; Brennan Less; Brett C Singer, and Iain S Walker.

Smart Ventilation for Advance California Homes – Single Zone Technology Task

Authors: Less, Brennan; Spencer M Dutton; Xiwang Li; Jordan D Clark; Iain S Walker, and Max H Sherman.

2018

Energy Savings Estimates for Occupancy and Temperature-based Smart Ventilation Control Approaches in Single-family Homes

Authors: Clark, Jordan D; Iain S Walker; Brennan Less; Spencer M Dutton; Xiwang Li, and Max H Sherman.

Rethinking Occupancy-Based Ventilation Controls

Authors: Walker, Iain S, and Brennan Less.

Energy Savings Estimates for Occupancy- and Temperature-based Smart Ventilation Control Approaches in Single-family California Homes

Authors: Clark, Jordan D; Iain S Walker; Brennan Less; Spencer M Dutton; Xiwang Li, and Max Sherman.

2017

Smart Ventilation Controls for Occupancy and Auxiliary Fan Use Across U.S. Climates

Authors: Less, Brennan, and Iain S Walker.

2016

A Literature Review of Sealed and Insulated Attics—Thermal, Moisture and Energy Performance

Authors: Less, Brennan; Iain S Walker, and Ronnen M Levinson.

Development of Smart Ventilation Control Algorithms for Humidity Control in High-Performance Homes in Humid U.S. Climates

Authors: Less, Brennan; Iain S Walker, and Sara Ticci.

Smart Ventilation Control of Indoor Humidity in High Performance Homes in Humid U.S. Climates

Authors: Less, Brennan, and Iain S Walker.

A Field Study of Wall Furnace Venting and Coincident Exhaust Fan Usage in 16 Northern CA Apartments

Authors: Singer, Brett C; Brennan Less; William W Delp; Andrew D Brooks; Sebastian Cohn, and Brian Finn.

Results of the California Healthy Homes Indoor Air Quality Study of 2011–2013: impact of natural gas appliances on air pollutant concentrations

Authors: Mullen, N A; J Li; Marion L Russell; Michael Spears; Brennan Less, and Brett C Singer.

2015

Assessment of Literature Related to Combustion Appliance Venting Systems

Authors: Rapp, Vi H; Brett C Singer; J Chris Stratton; Craig P Wray, and Brennan Less.
06/2012

Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: Impact of Natural Gas Appliances on Air Pollutant Concentrations

Authors: Mullen, Nasim A; Jina Li; Marion L Russell; Michael Spears; Brennan Less, and Brett C Singer.
03/2015

Deep Energy Retrofit Guidance for the Building America Solutions Center

Authors: Less, Brennan, and Iain S Walker.
01/2015

Indoor Air Quality in 24 California Residences Designed as High-Performance Homes

Authors: Less, Brennan; Nasim A Mullen; Brett C Singer, and Iain S Walker.

2014

A Meta-Analysis of Single-Family Deep Energy Retrofit Performance in the U.S.

Authors: Less, Brennan, and Iain S Walker.

Houses are Dumb without Smart Ventilation

Authors: Walker, Iain S; Max H Sherman, and Brennan Less.

An Assessment of Envelope Measures in Mild Climate Deep Energy Retrofits

Authors: Walker, Iain S, and Brennan Less.

Deep Energy Retrofit Performance Metric Comparison: Eight California Case Studies

Authors: Walker, Iain S; Brennan Less, and Jeremy Fisher.

Indoor Air Quality and Ventilation in Residential Deep Energy Retrofits

Authors: Less, Brennan, and Iain S Walker.

Development of an Outdoor Temperature-Based Control Algorithm for Residential Mechanical Ventilation Control

Authors: Less, Brennan; Iain S Walker, and Yihuan Tang.

2012

Deep Energy Retrofits—Eleven California Case Studies

Authors: Less, Brennan; Jeremy Fisher, and Iain S Walker.
10/2012