Welcome To The Filtration Station by Positive Energy

Strap in, y'all - this is one is... technical. Capturing particles, even and especially the ones too small for you to see, are where the rubber meets the road for IAQ. This all-important task is the role of the often-overlooked air filter. Today we talk about one of the most important building science topics that many folks don't know enough about - air filtration. Who knew there was so many important considerations for this often overlooked and ignored component of our industry?

John Bloemer

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John is Director of Engineering for Aprilaire. Aprilaire is the leader in Residential IAQ products offering solutions that create a Healthy Home.  Aprilaire designs, engineers and manufactures products that control aspects of IAQ – temperature, humidity, fresh air and air purity.   

John graduated with a BSME from the University of Akron.  His 34-year carrier has been focused on product development and he has worked for Scott & Fetzer and Kohler before finding his home at Aprilaire 19 years ago.

Through his carrier, he has been awarded over 15 US and foreign patents.  He sits on many committees in ASHRAE and AHRI and is actively involved in the Building Science community.  With Aprilaire, John is responsible for leading a team of highly talented engineers and experts in IAQ product design and testing at the main office Madison, WI. 

He promotes healthy buildings as a system where all products work together to ensure the highest level of air quality possible while maintaining ease of use, energy efficiency and of course, the health and comfort of the occupants.

Special thanks to Aprilaire for their generous and continued support for the show. Please go check out their products - it helps us secure future sponsorship! :) 

Let's Get Legal-ish by Positive Energy

When we think about building science, we're thinking about systems and the unseen forces that contribute to the success or failure of a building. Some of the largest and most complicated systems and unseen forces in the AEC industry are the contracts that make or break a project. Join Kristof as he interviews construction attorney, Joe Basham, on all things funky and legal in the AEC industry.

Joe Basham


Joe Basham grew up in Monahans, a small town in West Texas, where he worked in the oil fields in 115 degree weather. He then traveled nearly 500 miles to Texas A&M University, where he graduated, cum laude, with a degree in Construction Science from the College of Architecture and dunked his ring in Shiner Bock.

He worked as runner for a big law firm in Austin, and then moved to the high plains where attended Texas Tech School of Law.  He graduated in 2002, magna cum laude, Order of the Coif, and was the Technology Editor of the Texas Tech Law Review. 

After law school, Joe joined Allensworth & Porter as an associate, was made a partner in 2007. He has been listed in Texas Super Lawyers from 2005 – 2018, and Best Lawyers 2014 – 2015, and Legal 500. He is now the managing partner at Austin-based construction law firm, Allensworth & Porter, and partners with clients from all facets of the construction industry, including owners, contractors, architects, and engineers to consult on contract negotiations, dispute management and resolution, and litigation and arbitration. Joe focuses on building long-term, strategic relationships with clients who care about working with a lawyer who knows the law, their business, and their industry.

Joe is a member of the Rotary Club of Austin, and is on the board of the Austin Chapter of the Building Enclosure Council (BEC).  He served on the Rollingwood City Council for 5 years, and was president of the Rollingwood Community Economic Development Corporation.  He is married to Karla, and they have two boys, Joe (9) and John (7).

Joe can be contacted at (512) 708-1250 and at jrb@aaplaw.com

Big thanks to Aprilaire for their continued and generous support of the podcast! 


Circus Or Symphony by Positive Energy

Construction is a serious and unforgiving business. The best minds in the business are masters of seeing connections and systems thinking. If you are really trying to make a difference in this industry the good news is that there’s a lot of work to do and questions to answer. 

  • How do you successfully organize and deliver high quality construction on time and within budget? 
  • How do you handle communication flow? 
  • How much do you rely on external consultants for expertise? 
  • How do you set and manage expectations with your client? 

In this episode, Kristof interviews Trevor Brown, the Quality Control Manager of JE Dunn Construction to discuss war stories and the inside baseball of commercial construction. 

Trevor Brown


If there's someone who understands complex systems, it's Trevor Brown. Trevor has 20 years of experience as a Quality Control Professional, holds LEED AP BD+C Accreditation, and multiple ICC and NICET Certifications. His role is diverse and includes assisting in planning, implementing, and supervising construction quality assurance programs in compliance with contract documents and supervise and mentor his QA staff in their construction quality professional and interpersonal skills. His work has allowed him to become an expert in field and office staff interpretation of company, owner, and government requirements and recommendations in relation to the quality construction methods and processes of the company.

Big thanks to Aprilaire for their continued and generous support of the podcast. 

Dirty Socks & Your HVAC Coil by Positive Energy

The original episode was meant to feature both Graeme Marsh, who we heard on the last episode, as well as Greg Long. None of us could have prepared for the fact that in the middle of the episode, Greg's ceiling had water pouring out of it. It was unexpected, to say the least! 

Fortunately for us, we got to catch up with Greg for a more in depth discussion. So what do dirty socks have to do with the lungs of our homes and buildings? Listen to this episode to learn more about smelly biofilms, probiotic cleaners and the tip of the thermodynamic spear - the all-powerful, but often-ignored HVAC coil. 

The heat exchanger coil in our HVAC system is where the magic of heat transfer happens - this is where the rubber meets the road when it comes to "conditioning" air. If the word "coil" is not connecting to a mental image, you can think of the radiator in your car. Just as in a car, when it's working you don't give your radiator much thought - we often ignore our HVAC coils, and at our peril. All of the indoor air we heat and cool flows through our HVAC coil. Unfortunately sometimes our magic, all-powerful coils are coated with a smelly, gelatinous, living glop in the form of an unwanted biofilm.

Listen to this episode to learn more about the under-reported reality of biofilms in HVAC equipment and what to do about them to keep your coil and conditioned air clean and odor-free.


Earl Gregory (Greg) Long, CIEC, ASCS

Mr. Long is president of IAQ Consulting Services Inc. in Belton, TX (not far from the Positive Energy and Building Science Podcast headquarters). IAQ Consulting Services Inc,  is a consulting firm that offers estimating, project management, specification writing, investigations services and project oversight specializing in HVAC system restoration and cleaning, coil cleaning, structure restoration and dehumidification, and content restoration, with focus on restorative processes over replacement when applicable.

Areas of additional experience include rust eradication and prevention within HVAC systems, fiberglass insulation removal and replacement with closed cell insulation within HVAC systems,drain pan restoration, water and air leakage and odor control. It is Mr. Long’s belief that there is apractical and logical solution for most building related projects and indoor air issues and it has always been his goal to find the most reasonable solution for the situation at hand.

Among his credentials are: 

  • Certified Indoor Environmental Consultant (CIEC) by American Council for Accredited Certification
  • Certified Mold Remediator (CMR) by American Council for Accredited Certification
  • Air System Cleaning Specialist (ASCS) by National Air Duct Cleaners Association
  • Certified IAQ Technician (CIAQT) by Texas Tech University
  • Certified Mold Investigator Professional (CMIP) by Texas Tech University
  • Certified De-flooding Specialist by Cleaning De-flooding Restoration Network Trained and practiced in Commercial Kitchen exhaust system cleaning

It gets better. This guy's everywhere! 

  • Board of Directors of the National Air Duct Cleaners Association (NADCA) – 6 years
  • President of the National Air Duct Cleaners Association (NADCA) – 2 terms
  • Standards writing committee, National Air Duct Cleaners Association (NADCA) – past 23 years
  • Inducted into the first class of the Hall of Fame for the National Air Duct Cleaners Association
  • Chairman, Indoor Air Quality Advisory Council, Texas Tech University – 2 years
  • Standards writing committee Air Conditioning Contractors of America (ACCA) – 1 year
  • Board of Directors of the Indoor Air Quality Association (IAQA) – 6 years in past Board of Directors of the Indoor Air Quality Association (IAQA) – currently
  • Board Officer of the Indoor Air Quality Association (IAQA) – 2 years
  • Chairman of the finance committee of the Indoor Air Quality Association (IAQA) – past 5 years

We're impressed by the list. 

Nasty HVAC Coils From The Field

Big thanks to AprilAire for their generous support and to The Humid Climate Conference for their generous and continued support. 

Architectural Yogurt by Positive Energy

Put on your microbiology hats, folks. This episode of The Building Science podcast will dive into the great unseen world of microorganisms all around us inside our buildings down to the level of the ecosystems that grow on our HVAC coils. We're truly at a time when the health sciences and the building sciences are becoming more closely related than ever before and the future is a weird, wonderful world of intersectional and interdisciplinary scientific inquiry. Join us as Kristof interviews, Graeme Marsh about the weirdness of biofilms that you can't even see right before your very eyes. 

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Graeme Marsh

Graeme Marsh

Graeme is the Managing Director of Z Bioscience and has somewhat of a polymathic career path. He spent 20 years working for global investment banks in Australia, Hong Kong, Japan and the UK, going on to found Future Business Concepts, Inc. in 1998; helping companies with Business Development, Product and Sales Strategy, Financing and Re-Structuring.  

The initial focus was on the Internet. His firm was involved in the creation of the JV between Melbourne IT and NeuStar that successfully established the .biz generic Top Level Domain. More recently Graeme assisted a client in the million dollar plus sale of its IP / Patent portfolio, and is currently assisting with a "Next Generation" data encryption firm, and a new Project Management system provider that goes beyond the Agile approach.

He has also worked with firms in the Oil & Gas sector, focusing on environmental projects including air and water remediation, as well as New Materials, especially in the concrete space, Manufacturing Technologies, and Corrosion Prevention.

His firm expanded its work with clients that focus on Environmental related areas, including companies that have a range of revolutionary Certified Green cleaning products (many of which are also Organic) that are having a profound impact on the bottom line in multiple industries, including HVAC applications (improved system energy performance and IAQ), Agriculture (Poultry, Hogs & Dairy), and All Purpose Cleaning (Assisted Living, Schools, Healthcare, General Janitorial and Retail).

From 2002 to 2006 Graeme was on the Board of The Japan Pragmatist Fund, a Japanese hedge fund specializing in small to medium capitalized companies. It closed in Dec 2006 and all investors received their initial capital back plus above market returns. Graeme is also serving on the Board of number of other ventures.

Notes From The Episode

Z BioScience

Email Graeme

Jessica Green's Ted Talks

Special thanks to The Humid Climate Conference for their generous and continued support for the show. If you haven't got tickets for this May's conference, they're nearly sold out! 

Our Homes, Our Health by Positive Energy

It's normal these days to pay attention to what we eat. But what about the steady diet of air we breathe and soak ourselves in?  The impact of homes on health somehow manages to stay below the radar. Even our language is a bit evasive. Why do we say "sick building syndrome"? The buildings aren't sick, the people are. 

This episode is a step toward helping this important topic get some long-overdue and much-needed attention. Join us for an interview with Bill Hayward and Carl Grimes that took place at the 2018 IAQA Conference in Chicago, IL. as we discuss the Hayward Healthy Home Score. We hope you enjoy, take the quiz yourself, and share with your friends and families. 

Learn More About The Hayward Score with this great, informative video.

 Does your home make you healthier or sicker?

Does your home make you healthier or sicker?

Bill Hayward

Bill is the founder of Hayward Score as well as the CEO and Chief Sustainability Officer of Hayward, a 95-year-old California lumber and building material supplier. Since 2008, when he, his wife, and their newborn daughter became sick in their “dream home,” Bill has been focused on combining building science and medical science into a compelling strategy to transform home construction so that homes will no longer degrade human health. 

In addition to his work on Hayward Score, he has also recently assumed the role of Chief Innovations Officer of H3, a subsidiary focused on cutting-edge products that transform the indoor environment.

LMB Journal, the leading magazine for the lumber/building material distribution channel, named him Entrepreneur of the Year (2015). In addition, he was named “20 Most Influential Leaders in the Industry” and Hayward was named “Dealer of the Year” for their work in driving sustainability in the industry. On the non-profit side, Bill is currently Chairman Emeritus of Forest Stewardship Council (FSC) and previously served as Chairman for the 5 years. He received his BS from UCLA and graduated from the Stanford Executive Program.

Carl Grimes

Carl joined the Hayward Score team in 2013 and brings more than 30 years of professional expertise to identifying and addressing the most critical issues to transform homes to healthy environments that fit individual needs. In addition, he has personally experienced living in unhealthy homes and has a deep understanding of the uncertainty, exhaustion, and skepticism inherent in the struggle that many face – that his home was not a safe and secure “castle,” but was instead contributing to his declining health and sense of well‐being.

He is nationally recognized as a professionally accredited Healthy Home Specialist (HHS) and a Certified Indoor Environmental Consultant (CIEC). 

Since 1987, he has worked nationally as a private consultant guiding people who suffer from unhealthy houses. He has developed action plans and verification methods designed to eliminate health issues in homes. He was elected to the Board of Directors of the national Indoor Air Quality Association (IAQA) in 2002, and recently served as their President. Carl is now the Vice President of Practice for the International Society of Indoor Air Quality and Climate. Carl has served on, created, and chaired a variety of committees writing industry consensus standards. He has collaborated with leading experts and researchers, analyzing the best approaches for restoring the indoor environment. He has chaired a committee that developed the course, Healthy Home Assessment: Principles and Practice, which is the follow‐on to the Essential Healthy Home Practitioner course by the National Center for Healthy Housing (www.nchh.org).  He is also the author of “Starting Points for a Healthy Habitat,” based on his and his client’s experiences of living in unhealthy homes and speaks both nationally and internationally on topics related to indoor air quality.

More Info

See this powerful video about Bill’s wife’s own story and journey of discovering the impact of indoor air quality on her life and the life of her family. 

Check out the Breezometer app for outdoor air quality monitoring.  Fun fact, the Foobot outdoor air reference is fueled by the Breezometer data feed. 

Also be sure to check out Jessica Green’s fascinating Ted Talk on the Indoor Microbiome. She talks about the simple (or complex) fact that our bodies and homes are covered in microbes -- some good for us, some bad for us. As we learn more about the germs and microbes who share our living spaces, TED Fellow Jessica Green asks: Can we design buildings that encourage happy, healthy microbial environments?

We saw Jessica speak in Houston at the Gulf Coast Green conference and her talk was captivating and insightful. She's a true leader in this new field of architectural scientific inquiry.

For an expanded discussion, check out the Ted Blog

 The microbiome! 

The microbiome! 

Thanks to The Humid Climate Conference for their generous and continued support of our show.


Respect The Trade, Build The Craft by Positive Energy

What do you really know about construction trades and their role in projects? Are their voices heard in the design process? Join us as Miguel interviews Kimberly Lewellyn live from the annual ASHRAE Conference and AHR Expo in Chicago for a wide ranging discussion on re-framing our perceptions of construction trades. 

For decades, the housing industry in the United States has become increasingly first cost oriented while energy codes simultaneously become more demanding. The implications of this dynamic have played out across design organizations and construction firms, but nowhere has it been felt more poignantly than by sub-contracted trade crews. Often these laborers are considered low-skill, interchangeable, and are thus exploited. And due to this unnecessarily assigned status, they are rarely involved in early design conversations to contribute their wealth of knowledge of construction realities. 

This dynamic can change with willing participants, but it takes more than just thought-experiments. We have to put into action new ways of thinking about contractural relationships, economic value, and design processes and collaboration. That's what this episode is all about. We'll explore a few simple ways to change the conversation and hopefully our minds about how trades are involved in our project teams.

Kimberly Llewellyn, CPHC

Kimberly Llewellyn was a Building Science consultant for the Positive Energy team for many years and is now both a Performance Construction Manager at Mitsubishi Electric Cooling & Heating and a PHIUS Certified Passive House Consultant (CPHC). Between her formal post-grad education in environmental engineering at Columbia University, Kimberly has an intimate understanding of how the HVAC industry relates to well designed and delivered homes and continues to advocate for better practices and collaboration in her work with Mitsubishi. 


Big thanks to The Humid Climate Conference for their generous and continued support of this show.

The Future Of Water Heaters Is Here by Positive Energy

John Miles, Sanden Hot Water Heaters

If you think you don’t need to worry about water heating, think again! In this episode, Kristof interviews John Miles of Sanden Hot Water Heaters live on the AHR Expo floor in Chicago about the future of water heating. Learn why this technology can make a massive impact on the housing and energy sectors. 

When most people think of a quality water heater (which rarely happens) they think of gas tankless or electric resistive tanked systems. But that's nowhere near the full story. Water heaters are the second highest energy users in most homes and most home owners have never been presented with a good accounting of the available options. 

Heat pump water based water heating is here to stay and split system water heaters are the next step forward in the evolutionary up-cycle. Add to the equation an incredible refrigerant, CO2, and you've got yourself a high performing, low exergy, and low Global Warming Potential (GWP) water heating unit that could actually change energy consumption at the grid level.

Here's the breakdown (these are generalized for simplicity):

-Gas Tankless Systems - 90% Efficiency

-Electric Resistive Tanked Systems - 95% Efficiency

-Conventional Non-Split Heat Pump - 250% Efficient

-Split System CO2 Based Heat Pump - 520% Efficient

Big thanks to Sanden for supporting the show and for talking with us at AHR and to The Humid Climate Conference for their continued and generous support of our show. 

Forget What You Know About Buildings: An Interview With Kiel Moe by Positive Energy

In this episode, Kristof interviews Kiel Moe of Harvard's GSD about the energy flows and multiple re-thinkings necessary to change the future of construction and design. You may remember reading about Kiel's inspiration to us at Positive Energy in our blog post about the thermally active surface system we installed in our office, compliments of the fine and wonderful people at Messana and SpacePak. This episode is definitely headier than most of ours, so buckle in and be ready to hit pause, rewind, and take notes if you need. We couldn't be more thrilled that he stopped by the office to chat. 

Kiel Moe


Kiel is a registered architect and has taught architecture and energy at University of Illinois at ChicagoSyracuse University and Northeastern University. He holds positions as Associate Professor of Architecture & Energy and Co-Director of Master of Design Studies program in Harvard Graduate School of Design.

Moe received the B.Arch from the University of Cincinnati, M.Arch from University of Virginia, and a Master in Design and Environmental Studies from the Harvard Graduate School of Design Advanced Studies Program. 

Professor Moe's research and pedagogy focuses on an agenda (theories, techniques, and technologies) for energy that is at once more ecologically and architecturally ambitous: Maximum Power Design. A such, he focuses on both buildings as manifestations of large scale energy systems as well as overlooked and discrete thermal parameters in buildings that yet have great impact on the power of a building.

Ideas To Unpack

Material Ecology: coined by Neri Oxman (Architect, Designer, Inventor), focuses on and considers computation, fabrication, and the material itself as inseparable dimensions of design. In this approach, products and buildings are biologically informed and digitally engineered by, with and for, Nature.

Energetics Of Urbanization:  deals with the relationship between energy flows, urbanization, and how they relate to economic practices and theories. Learn more about Neil Brenner and his work here.

Pedagogy: how we relate to, study, and implement teaching.

Planetary Urbanization: thinking about how we urbanize at a planetary level, how that affects resource and energy flows, and how life on the planet is shaped by it. 

Howard Odum: a brilliant ecologist who had a profound impact on the economic theories of energy flow. He coined the term and developed the theory of emergy, which deals with the embodied energy of any given object or structure.

Epistemology: how do we know what we know? Pretty much. 

Political Economy: the study of production and trade and their relations with law, custom and government as well as with the distribution of national income and wealth.

Adrian Bejan:  a brilliant mechanical engineer who first stated the notion of Constructal Law, which is the law of physics that accounts for the phenomenon of evolution (configuration, form, design) throughout nature, inanimate flow systems and animate systems together.

For a finite-size system to persist in time (to live), it must evolve in such a way that it provides easier access to the imposed currents that flow through it.
— Adrian Bejan, The Constructal Law

The constructal law places the concepts of life, evolution, design and performance in physics, which is in the broadest scientific arena. The constructal law is the law of physics of life and evolution. 

Forest Ecology: how do you get the wood that you use? 

Big thanks to the Humid Climate Conference for their generous support of our podcast and to Brittney Spears for the music that's stayed with us all these years.


The Secret Life Of Concrete by Positive Energy

Concrete is everywhere. We all see it every day but what do we really know about concrete? This seemingly simple material is any but simple. Listen and learn about the past, present and future of this evolving technology. Prepare to have your mind blown in this episode of the show as we explore the incredible history and composition of concrete with Matt Carlton and Lee Lawrence of WJE. You'll never see concrete the same way again.

Our Guests


Lee Lawrence

Principal, Director of Practice Development, and South Region Director at WJE.


Matt Carlton

Principal & Unit Manager at WJE.

Notes From The Episode


(/riːˈɒlədʒi/; from Greek ῥέω rhéō, "flow" and -λoγία, -logia, "study of") is the study of the flow of matter, primarily in a liquid state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. It is a branch of physics which deals with the deformation and flow of materials, both solids and liquids.

Flying buttress

(arc-boutant, arch buttress) a specific form of buttress composed of an arched structure that extends from the upper portion of a wall to a pier of great mass, in order to convey to the ground the lateral forces that push a wall outwards, which are forces that arise from vaulted ceilings of stone and from wind-loading on roofs.

The defining, functional characteristic of a flying buttress is that it is not in contact with the wall it supports, like a traditional buttress, and so transmits the lateral forces across the span of intervening space between the wall and the pier. To provide lateral support, flying-buttress systems are composed of two parts: (i) a massive pier, a vertical block of masonry situated away from the building wall, and (ii) an arch that bridges the span between the pier and the wall — either a segmental arch or a quadrant arch — the flyer of the flying buttress.

The Pantheon (Was Built Out Of Concrete)

The building is circular with a portico of large granite Corinthian columns (eight in the first rank and two groups of four behind) under a pediment. A rectangular vestibule links the porch to the rotunda, which is under a coffered concrete dome, with a central opening (oculus) to the sky. Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome. The height to the oculus and the diameter of the interior circle are the same, 142 feet (43 m).

Portland Cement

Portland cement is the most common type of cement in general use around the world as a basic ingredient of concretemortarstucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the mid 19th century, and usually originates from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinkergrinding the clinker, and adding 2 to 3 percent of gypsum.[clarification needed] Several types of Portland cement are available. The most common, called ordinary Portland cement (OPC), is grey in colour, but white Portland cement is also available. Its name is derived from its similarity to Portland stone which was quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. However, his son William Aspdin is regarded as the inventor of "modern" Portland cement due to his developments in the 1840s.[1]

Concrete Petrography

Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. The classification of rocks is based on the information acquired during the petrographic analysis. Petrographic descriptions start with the field notes at the outcrop and include macroscopic description of hand specimens. However, the most important tool for the petrographer is the petrographic microscope. The detailed analysis of minerals by optical mineralogy in thin section and the micro-texture and structure are critical to understanding the origin of the rock. Electron microprobe analysis of individual grains as well as whole rock chemical analysis by atomic absorption, X-ray fluorescence, and laser-induced breakdown spectroscopy are used in a modern petrographic lab. Individual mineral grains from a rock sample may also be analyzed by X-ray diffraction when optical means are insufficient. Analysis of microscopic fluid inclusions within mineral grains with a heating stage on a petrographic microscope provides clues to the temperature and pressure conditions existent during the mineral formation.

Board Form Concrete


Event - Not Your Father’s Concrete!: A breakfast seminar and networking opportunity

Join WJE for a presentation and discussion of the perils of ready-mix concrete and the state of practice. We will also discuss self-consolidating concrete, the advantages and disadvantages as well as new-age additives and what works best when.

This program will qualify for AIA/AICP Continuing Education Credits.


Special thanks to The Humid Climate Conference for their generous support.

Design & Construction In Humid Climates by Positive Energy

Yes. We're going to have a chat about humidity. If you live in a heating dominated, dry climate you might be thinking "what good is this for me to hear?" and I wouldn't blame you. But frankly, the more we know about humidity, the better we can understand how things work without it too. So dig in and think about how moisture affects the things we design and build. In this episode of The Building Science Podcast, we’ll explore the potential upside and downside of designing and building in humid climates.

If you're serious about building high performance homes in humid climates, you don't want to miss this year's Humid Climate Conference in Austin. Tickets are on sale now and we at The Building Science Podcast are thrilled to sponsor this year's conference. Don't miss it! The Humid Climate Conference is organized entirely by volunteers from the PHAUS (Passive House) Chapter in Austin with support from the national organization, PHIUS


What Is A Climate Zone?

DOE climate zone map.preview.jpg
One of the fundamental principles of building science is that buildings must be suited to their climate. When they’re not, problems can ensue. Maybe it’s just that they’re not as efficient as they should be. Maybe it’s worse. Put plastic between the drywall and framing of your exterior walls in Ottawa, and it can help control vapor drive from the interior air and its associated moisture problems (rare in all but except in extremely cold climates). Put that plastic in the same place in Georgia, and you’re going to rot the walls.

The first thing to know about climate zones is that we divide them up based on two parameters: temperature and moisture. The map at the top of this article, from Building Science Corporation, is one that seems to be in a lot of the curricula for home energy rater and other energy auditor classes. The fancy word for this type of division is hygrothermal, and Building Science Corp. has a nice interactive map of hygrothermal regions.

The map above divides all of North America into broad regions based on temperature and then humidity. The International Code Council has a more fine-grained approach to climate zones,† as shown below in the map of the US from the International Energy Conservation Code (IECC). Each zone has a number, starting with 1 for the hottest US climate, the southernmost tip of Florida, and going up to 8, the coldest parts in Alaska.
— Dr. Allison Bailes, III

Aridity & Humidity: Where & Why? 


Special thanks to Panasonic for their generous support. 


Don't Wait For The Market by Positive Energy

In our first episode of season 4, Kristof interviews James Geppner of Erase40 and Big Yellow Cab on the topic of behavioral change and market transformation. Building Science stands poised to change the way we deliver conditioned space to society. There are many angles by which we can dissect exactly how to do that. In this episode, we're going to explore how YOU can change the market.


James Geppner

James has advised and developed initiatives for nonprofits, new ventures and mature companies in infrastructure, technology, media, education, health and housing. Following his years in Project Finance, where he evaluated companies and studied markets, he has applied social science (and competitive theory) to a range of issues in order to see what’s shaping a market, a cause or a behavior.

He founded Big Yellow Cab in order to apply social science research and the procedures of behavior change to important social and environmental issues. He has advised nonprofits, new ventures and global companies. Most recently he did an extensive analysis of the market for passive buildings and the decision-making process of buyers, funders and end users in order to find clues as to how to increase the size of the market and how to reduce the barriers to widespread adoption of passive technology. He founded Erase40 in order to develop market based initiatives that drive up demand for passive buildings and in order to serve as a decision lab for different players in the building ecosystem. He is a graduate of NYU and of SGIB’s investment banking program. 


Big Yellow Cab
Freakanomics Radio Episode (Mentioned) 

Special thanks to Panasonic for their generous support.



The Beauty Of Hot Water by Positive Energy

Live from the Texas Society of Architects 2017 Expo and Convention, we're proud to bring you a series of episodes exploring "the multiple dimensions of beauty" through interviews with some phenomenal architects, builders, and consultants. 

In this episode we interview water engineering expert, Gary Klein of Gary Klein & Associates.

Gary Klein

Gary Klein, President of Gary Klein & Associates has been intimately involved in energy efficiency and renewable energy since 1974. One fifth of his career was spent in the Kingdom of Lesotho, the rest in the United States. Mr. Klein has a passion for hot water: getting into it, getting out of it and efficiently delivering it to meet customers' needs. 

After serving 19 years with the California Energy Commission, he has provided consulting on sustainability since 2008. Mr. Klein received a BA from Cornell University in 1975 with an Independent Major in Technology and Society with an emphasis on energy conservation and renewable energy.

Special thanks to Bautex Systems for their generous support of our live recorded episodes at the 2017 TxA Expo & Convention. Be sure to stop by their website, learn about their innovative product, and say hello for us.


The Beauty Of A Healthy Building by Positive Energy

Live from the Texas Society of Architects 2017 Expo and Convention, we're proud to bring you a series of episodes exploring "the multiple dimensions of beauty" through interviews with some phenomenal architects, builders, and consultants. 

This episode features an interview with Dr. Jules Elkins of The University Of Texas at Austin and The East Wall Consulting

Dr. Jules Elkins

Dr. Elkins’s research and teaching is in environmental health, and healthy indoor environments. She is particularly interested in low-dose chemical exposures, especially during the period from preconception to early childhood. Her interests focus on how exposures can be practically and cost-effectively reduced or prevented based on evidence-based models of what interventions measurably work. Specific projects and work includes exposures in schools from poorly ventilated classrooms, exposures from proximity to highly trafficked roadways, and maternal and child exposures from the food they eat. Dr. Elkins is particularly interested in the concept of the Healthy City. Given that we increasingly live in an urbanized world, how can we design away our environmental health problems, and what are the evidence-based outcomes from such design, considering both health and economic metrics? Dr. Elkins also speaks and consults on constructing healthy buildings. This includes choosing healthy materials, optimizing healthy design, and evidence-based outcomes of exposures in indoor environments. This work ranges from green buildings to building for clients with chemical sensitivities.

Big thanks to the Texas Society of Architects and our sponsor Bautex.



The Beauty Of Climate Appropriate Design by Positive Energy

Live from the Texas Society of Architects 2017 Expo and Convention, we're proud to bring you a series of episodes exploring "the multiple dimensions of beauty" through interviews with some phenomenal architects, builders, and consultants. 

This episode features an interview with Peter Pfeiffer of Barley Pfeiffer Architecture

Peter L Pfeiffer, FAIA

Peter Pfeiffer wears many hats.  He is a LEED accredited professional Architect,  a licensed Interior Designer,  Building Scientist and Property Developer & Manager, who has spent the past 36 years designing and developing pragmatic high performance buildings and homes.

 EEBA, the national Energy Efficient Building Association, awarded Mr. Pfeiffer the Conference Chair’s Award in 1994 for his career accomplishments pioneering environmentally sensitive architecture.   In 2004 he was one of the first architects in America to be named a Fellow of the American Institute of Architects for his life-long commitment to "mainstreaming green building in North America”.  He is a founding principal of Barley | Pfeiffer Architecture, a firm recognized nationally for its pioneering use of environmentally responsive design and construction techniques.  Their work has been published both in the United States and abroad in such diverse venues as the Washington Post, The New York Times,  Fine Homebuilding,   Better Homes & Gardens magazine and on-line where they have been awarded “Best Of Houzz” in the Design and Service categories for two consecutive years.  He has been a guest on National Public Radio, the HG-TV network, as well as on The Discovery Channel and This Old House.

The National Association of Home Builders honored him as the “National Green Advocate of the Year” in 2003 for his life-long achievements in “mainstreaming” green building.  Peter has been an active charter member of the NAHB Green Building Subcommittee since its inception in 1999 and has been active in the US Green Building Council’s LEED for Homes program.  In 2006 Residential Architect cited him as one of the 10 most influential residential architects of past decade.  Recently Peter was nominated for the prestigious Hanley Award for his meaningful efforts to advance green building in America. 

Special thanks to Bautex Systems for their generous support of our live recorded episodes at the 2017 TxA Expo & Convention. Be sure to stop by their website, learn about their innovative product, and say hello for us.


The Beauty Of Urban Infill by Positive Energy

Live from the Texas Society of Architects 2017 Expo and Convention, we're proud to bring you a series of episodes exploring "the multiple dimensions of beauty" through interviews with some phenomenal architects, builders, and consultants. 

This episode features an interview with Kristen & Michael Padavic of PSW Real Estate

PSW Real Estate

PSW Real Estate, LLC is a Texas real estate developer that designs and builds communities of high-quality green homes in urban areas. PSW creates homes that offer proximity to work, school and other important resources while implementing energy efficient construction methods and materials. These key elements promote urban density and conservation, reduce waste, and engender social connectivity.

Michael Padavic

Michael joined PSW in late 2011 to develop and lead the newly created design and planning group within the office as part of an initiative to move the architectural development of PSW Homes in house, an aim for greater efficiency and unified vision.

After achieving a Master in Architecture from Harvard University’s Graduate School of Design, Michael honed his skills working for several small to mid-size firms in Chicago, managing a variety of projects from high-rise residential towers and high-end renovations to school restoration and public libraries. He currently holds architectural licenses in both Illinois and Texas.

Specialties: Single family, multi-family and commercial architecture; Sustainable design; Building Information Modeling (BIM)

Kristen Padavic

Kristen moved her family (with Michael, above) to Austin, Texas to join PSW, and Austin-headquartered urban infill home builder after working in Chicago, IL for nearly a decade.  Over the past several years, her architectural team has grown to nearly ten employees, as the PSW team has grown into multiple markets in Texas and Seattle. The team is comprised of a variety of disciplines, including architecture, civil engineering, construction and sales, that all bring unique expertise to the process of designing urban infill communities.


Special thanks to Bautex Systems for their generous support of our live recorded episodes at the 2017 TxA Expo & Convention. Be sure to stop by their website, learn about their innovative product, and say hello for us.


TxA Positive Energy

Season 3 Reflections | Season 4 Preview by Positive Energy

Pour yourself a hot drink, grab a blanket and sit near the crackling logs for this holiday special episode. We're looking back at the last 3 years and looking ahead to our 4th season of the show. Be sure to check out our end of year survey and submit your ideas for episodes in season 4!

Thank you so much for listening to our show for the last 3 years. We plan on delivering more great episodes in 2018 and hope you'll join us for the ride! 

The Beauty Of Performance by Positive Energy

Live from the Texas Society of Architects 2017 Expo and Convention, we're proud to bring you a series of episodes exploring "the multiple dimensions of beauty" through interviews with some phenomenal architects, builders, and consultants. 

This episode features an interview with Darrell McMaster, a builder from Boerne, TX who runs a company called Sustainable Homes of Texas

Darrel has been building homes for over 40 years. He comes from a family of builders, with three generations still active in the home building industry. He is a Master Builder, proud of his craft, and forward thinking in his application of systems and processes.

Darrel says, “the theory is simple if you have to frame on top of the concrete you set up, or build the cabinets that are attached to the wall that you framed you are going to do it right the first time”. 

He's experienced in production, multi-family and custom home building and endeavoring to show that sustainable homes are not only affordable but possible, not only in custom homes but in production homes, as well as multi-family communities.

Special thanks to Bautex Systems for their generous support of our live recorded episodes at the 2017 TxA Expo & Convention. Be sure to stop by their website, learn about their innovative product, and say hello for us.

Knowing & Using VRF by Positive Energy


Apologies for the inconvenience with the last audio file - it appeared to be fine on our side, but was corrupted in the upload process. We appreciate all the feedback and are so thrilled you couldn't wait to hear more! As requested, a new file has been uploaded on a solid connection. Please let us know if you're experiencing any issues and enjoy the episode! 


Positive Energy has built its success around deeply understanding enclosures and how they interact with mechanical systems. We intimately know the HVAC equipment out there. And it hasn’t been easy to get architects, builders, and installers to adopt a new and “unknown” technology. But that’s exactly what we endeavor to do with each project. And you’ve probably guessed by now that we’re talking about VRF here. 

It’s a big deal. It’s the way our industry is headed. And it’s worth understanding and using on your projects. 

In this second of the two part series on VRF, The Building Science Podcast brings you a whole host of information on VRF systems to help you better know, understand, and implement this technology in your projects with a great conversation between our host Kristof and guest John Chavez. Thanks to the generous support of Mitsubishi Electric Cooling & Heating, we're proud to bring you this latest installment of The Building Science Podcast focused on VRF technology and how to bring it to your projects.

Stucco - (Much) More Than Meets The Eye by Positive Energy

Special Edition - Just Released. Listen and learn why you don't want to miss this event! Coming up next Friday 10/13/2017 here in Austin. 

Join Kristof Irwin and guest experts Matt Carlton and Brian Roeder for lively discussion on the surprisingly rich topic of stucco cladding systems. You'll never look at a stucco wall the same way again.

Special thanks to UltraAire for their generous support.

Symposium Details 

Hosted by: AIA BEC: Austin & RCI, Central Texas
Date & Time: Friday, October 13th, 8:30am-5:30am, registration opens at 8:00am
Location: JJ Pickle Research Center, Commons Conference Center, 10100 Burnet Rd, Austin, TX 78758
Price: Early Bird (unitl 9/15) $150/person, General Admittance (9/16-10/12) $190/person, Day Of (10/13) $225
CEUs: 6.5 LU AIA HSW Credits