The Building Science Podcast

Kristof interviews Dr. Sarah Haines
The Indoor Microbiome is the complex, invisible world of microorganisms living within our daily surroundings, serving as the primary ecological interface through which buildings influence human biology. In this light, we are beginning to view indoor environments not merely as passive shelters, but as powerful positive health interventions that can actively shape our immune development and long-term wellbeing.
Today, we are joined by Dr. Sarah Haines, Assistant Professor at the University of Toronto and Principal Investigator of the IMEE Lab, to explore the foundational framework behind this shift. We will discuss the emerging perspective of "biologically informed architectural design" and the fact that architects and interior designers don’t just curate materials, they curate our basic microbial exposures and therefore our health and wellbeing.

Sarah Haines
Dr. Sarah R. Haines is an interdisciplinary researcher and educator working at the intersection of building science, environmental engineering, and microbiology to investigate how indoor environments shape human health. Assistant Professor in the Department of Civil and Mineral Engineering at the University of Toronto, the Principal Investigator of the Indoor Microbiology and Environmental Exposures (IMEE) Lab and member of the Hub for Advancing Buildings. She holds a BS in Environmental Engineering and an MS and PhD in Environmental Science from The Ohio State University. Her research focuses on maintaining healthy and sustainable indoor environments through detection and characterization of abiotic and biotic indoor exposures using a variety of techniques​. She integrates community-based participatory research, advanced molecular techniques (e.g., high-throughput sequencing, digital PCR, metatranscriptomics) and filter forensics to examine microbial dynamics and contaminant exposures indoors.
Her work includes studies of moisture-driven mold growth in building materials, microbial volatile organic compound emissions, and the use of filter dust to estimate airborne concentrations of contaminants and pathogens, including SARS-CoV-2. Through this research, she develops practical, evidence-based strategies to reduce harmful indoor exposures, particularly in the context of climate change and housing inequities.
Prof. Haines is a member of the American Association for Aerosol Research (AAAR) and the International Society of Indoor Air Quality and Climate (ISIAQ), as well as the Institute of Health Emergencies and Pandemics (IHEP) contributing to interdisciplinary efforts that connect indoor air quality, building performance and health. She was the 2024 recipient of the University of Toronto Faculty of Applied Science & Engineering Early Career Teaching Award, recognized for excellence in teaching and mentorship.

Team
Hosted by Kristof Irwin
Edited by Nico Mignardi
Produced by M. Walker

Kristof interviews Benjamin Jewell.

This is Part 2 of our latest series to familiarize our industry with the world of hydronics systems and air-to-water heat pumps. In Part 2 we’re rejoining the conversation to look at controls - the "central nervous systems" of these hydronics. We’re moving beyond old-school mechanical switches to a new class of microprocessor based systems that prioritize "outcomes"—like thermal comfort and air quality—rather than just reacting to thermostat calls. This shift is about adding intelligence that anticipates comfort needs and makes the system more stable and predictable for both the installer and the homeowner .
We also dive into the high-stakes world of the global refrigerant transition and how hydronic systems allow a home to become "refrigerant agnostic" and truly future-proofed . We unpack the potential of natural refrigerants like R-290 (propane) and discuss why builders and developers are the key stakeholders in the transition of this product class from high-end homes to the baseline approach for every home that’s built. We wrap up by looking at how simplified "kit" solutions are finally removing the traditional barriers of labor and complexity to make hydronics accessible for the mainstream market.

Benjamin Jewell
Director of Carrier Hydronics NA (Climate Solutions Americas)
As the Director of Carrier Hydronics North America within the Climate Solutions Americas division, Ben Jewell leads a multifaceted organization comprising Product, Engineering, and Technical Services teams. His leadership spans the entire product lifecycle, from initial development and long-term strategic planning to the integration of digital tools and portfolio management. Ben is dedicated to stewarding residential and light commercial hydronic products across a diverse range of differentiated brands, driving his team to win every day through innovation and operational excellence.
Before joining Carrier, Ben spent over four years as a Senior Product Line Manager for Viessmann Climate Solutions. During this time, he managed extensive portfolios in the residential and light commercial sectors, specializing in heat pumps, chillers, domestic water heating, ventilation, indoor air quality, and air distribution. This deep technical foundation informs his current approach to solving complex climate challenges and delivering high-performance solutions to the market.
Beyond his executive responsibilities, Ben is a passionate advocate for mentorship and industry education. He frequently invests his time in sharing resources and supporting those looking to solve tough problems that make the world a better place, including contributing to industry knowledge through podcasting. Driven by the goal of being a proactive force in the world, Ben aims to look back on his career with the confidence that he "happened to the world" by making a tangible, positive impact on the industry and the environment.
On a personal level, Ben is a devoted husband and a father to three daughters, a dog owner, and a "food rescue" enthusiast. While he describes himself as an average fly fisherman and perhaps a naturalist in another life, he spends the bulk of his days enjoying what he considers his dream career. His journey has taken him from Iowa City to Milford, Connecticut, and Stony Brook, New York, eventually leading him to his forever home base in Fort Collins, Colorado. Despite his many moves, he remains a loyal Iowa Hawkeye at heart—Go Hawks!

Team
Hosted by Kristof Irwin
Edited by Nico Mignardi
Produced by M. Walker

“First we shape our buildings, thereafter they shape us.”
- Winston Churchill (attributed)

The natural world is humanity's original habitat. This habitat supports our physiological energy efficiency and is an important health intervention for the AEC industry. These are core perspectives that Helena van Vliet shares in this joint PHA-Building Science Podcast interview. Helena makes the clear case that we are “open systems” - we take in our environments, both physically and with our perceptions. Whether outdoors or indoors, our physical selves have their own experience of each environment we inhabit. This experience first informs our bodies, which have their own reactions of ease or dis-ease; and next, seemingly at the same time, this experience then informs our minds and our psychological reality comes to life. This interview is yet another beacon guiding us to deeply rethink how we deliver indoor spaces to ourselves. Enjoy the nourishing feast of ideas here!

Helena van Vliet
Helena van Vliet Dipl.-Ing. AIA is an internationally recognized expert in Biophilic Design. She is a registered Architect, Consultant, Researcher, Educator, and Speaker focusing on the direct connections between human and bio-habitat resilience in built environments.
In her designs, consulting work and teaching, she integrates insights from her 40 years of practice, as well as data from her ongoing research in evolutionary biology, cognitive neuroscience, biopsychology, and chronobiology. Helenais the Principal at Helena van Vliet LLC, as well as a founding member of BioPhilly. Since 2013, she has served as a Steering Committee Member for the International Biophilic Cities Network.
Since 2018, Helena has taught her interdisciplinary seminar “Environments for Well-Being” at Thomas Jefferson University, bringing together design and health science students to explore the building blocks - and underlying science - of spaces that support well-being. She is a frequent lecturer at the University of Pennsylvania, Drexel, Widener, the Bauhaus University Weimar, Germany, and the Politecnico di Milano, Italy.

Ilka Cassidy
Ilka Cassidy, Dipl.-Ing. Architecture, CPHC, is the co-founder of C2 Architecture and Holzraum System, with a deep passion for Passive House envelope design and building science. She focuses on the benefits of using natural building materials and specializes in offsite construction.
With extensive experience in Passive House consulting and energy modeling, Ilka has a strong understanding of energy efficiency strategies. As a co-founder of C2 Architecture, she brought a sustainable design perspective to the firm from its inception. Through Holzraum System, she has worked to merge the precision and scalability of prefabrication with the use of healthy, low-carbon materials, all while optimizing energy efficiency with Passive House principles.
Ilka is also committed to expanding knowledge in the industry, serving as co-host of the Passive House Accelerator Podcast and Construction Tech Live events. She is a frequent conference speaker and an active member of Green Building United in Philadelphia. She is a proud mom for her three girls and a visiting educator and McGill University.

Team
Hosted by Kristof Irwin
Edited by Nico Mignardi
Produced by M. Walker

In this episode we are once again diving into the world of hydronics systems and air-to-water heat pumps. These systems are poised to transform how we heat and cool homes and buildings in the US. In this Part 1 of a two part series, we’ll be tracing the historical "divergence" that pushed the US toward forced-air ducting while Europe stayed with the efficiency of water to move heat around inside buildings - remember that “moving heat” includes cooling. We discuss the basic components and function of hydronic systems in a guided component-level tour. We explain the potential to combine space heating and cooling with hot water production and the importance of simple components like buffer tanks that allow for load "decoupling"—the ability to store thermal energy and shift your home's energy loads to times when electricity is cheapest or the grid is less stressed.

Benjamin Jewell
Director of Carrier Hydronics NA (Climate Solutions Americas)
As the Director of Carrier Hydronics North America within the Climate Solutions Americas division, Ben Jewell leads a multifaceted organization comprising Product, Engineering, and Technical Services teams. His leadership spans the entire product lifecycle, from initial development and long-term strategic planning to the integration of digital tools and portfolio management. Ben is dedicated to stewarding residential and light commercial hydronic products across a diverse range of differentiated brands, driving his team to win every day through innovation and operational excellence.
Before joining Carrier, Ben spent over four years as a Senior Product Line Manager for Viessmann Climate Solutions. During this time, he managed extensive portfolios in the residential and light commercial sectors, specializing in heat pumps, chillers, domestic water heating, ventilation, indoor air quality, and air distribution. This deep technical foundation informs his current approach to solving complex climate challenges and delivering high-performance solutions to the market.
Beyond his executive responsibilities, Ben is a passionate advocate for mentorship and industry education. He frequently invests his time in sharing resources and supporting those looking to solve tough problems that make the world a better place, including contributing to industry knowledge through podcasting. Driven by the goal of being a proactive force in the world, Ben aims to look back on his career with the confidence that he "happened to the world" by making a tangible, positive impact on the industry and the environment.
On a personal level, Ben is a devoted husband and a father to three daughters, a dog owner, and a "food rescue" enthusiast. While he describes himself as an average fly fisherman and perhaps a naturalist in another life, he spends the bulk of his days enjoying what he considers his dream career. His journey has taken him from Iowa City to Milford, Connecticut, and Stony Brook, New York, eventually leading him to his forever home base in Fort Collins, Colorado. Despite his many moves, he remains a loyal Iowa Hawkeye at heart—Go Hawks!

Team
Hosted by Kristof Irwin
Edited by Nico Mignardi
Produced by M. Walker

Windows are pivotal to the lived experience of a home. They impact the basic aesthetic and provide natural light, views, ventilation, and safety. However, they are also nearly always the largest single source of heat loss and gain - it's hard to overstate the importance of getting windows right, as they play a huge role in a building's energy use. Today, we're going to take a deep dive into high-performance architectural windows, exploring the technology that lets us control unwanted heat flow through conduction, convection, and radiation. We'll be looking at the technical specs U-factor, Solar Heat Gain Coefficient (SHGC), air leakage and visual transmittance, as well as the fundamental differences between US and European manufacturing philosophies.

Article from Passive House Accelerator:
How Windows Make (Or Break) Wall Performance

Andrew Dryden
Andrew Dryden is the Owner of Pivot Windows LLC. He is dedicated to promoting sustainable construction practices that enhance energy efficiency and overall building performance. His journey began during a transformative sabbatical year in the Pacific Northwest, where he constructed his own high-performance home. This hands-on experience ignited his passion for innovative building solutions and laid the foundation for Pivot Windows LLC.
At Pivot Windows, Andrew is at the helm of several key projects aimed at increasing the accessibility of high-performance windows for residential and commercial clients. His strategic approach to program management ensures that each project is executed with precision, from initial concept to final installation. By fostering strategic partnerships within the industry, Andrew is able to source cutting-edge products that meet the evolving needs of the market while maintaining affordability for his clients.

Team
Hosted by Kristof Irwin
Edited by Nico Mignardi
Produced by M. Walker