Home Diagnosis TV - Bringing Building Science To The Mainstream by Positive Energy

Greetings building science enthusiasts! 

We're excited to share and help promote a brand new show that will air on PBS in 2019 called Home Diagnosis TV. Our friend and colleague, Corbett Lunsford, and his wife Grace have been working tirelessly the last few years to make this project a reality and we are so proud of the result. You may have seen Corbett & Grace before on their Proof Is Possible U.S. tour. You'll be seeing a lot more from us about this show as it launches. 

Here's the description from the Home Diagnosis TV website:

Home Performance Experts Grace and Corbett Lunsford created this 6-episode 30-minute series coming to your television in 2019! Shot in cities across the U.S. as part of the Proof Is Possible Tour, the show follows Corbett and Grace as they solve mystery problems of all types in homes new and old. Presented by Georgia Public Broadcasting with post-production by ECG Productions.

Check out the sizzle reel and feel free to share this with folks you think would like a show like this. Education and advocacy is incredibly important to making a "new normal" in our industry. When homeowners demand better performance, architects, builders, installers, and real estate agents will change their value systems to provide the kind of homes that benefit us all. 

Home Diagnosis is a 30-minute series coming to your television in 2016! Shot in 16 cities across the U.S. as part of the Proof Is Possible Tour, the show follows Corbett and Grace as they solve mystery problems of all types in homes new and old.

We've also got a great episode of The Building Science Podcast coming up in a few weeks with an awesome interview between Kristof and Corbett on the HOMEChem experiments that were being conducted alongside the filming of this new show, so be on the lookout for that. Of course, we're really excited about the potential of Indoor Air Quality education coming to the masses. It's the future fulcrum point of housing and health care. 

A brief description of HOMEChem:

The HOMEChem experiment (House Observations of Microbial and Environmental Chemistry) will take place in the month of June 2018, incorporating measurements from over 15 research groups from 9 universities to identify the most important aspects of the chemistry that controls the indoor environment. The HOMEChem field study is expected to kick-start and energize the Chemistry of Indoor Environments community of scientists, while also answering interesting preliminary science questions on the chemistry of indoor environments in a real-world experimental setting. This brings an excellent opportunity for outreach to the broader scientific community and other stakeholders, such as other funding agencies, the local and national media, and the public.
Meet some of the heroes of HOMEChem (House Observations of Microbial and Environmental Chemistry) and the University of Texas-Austin's Test House! Subscribe and stay tuned for more about this first-ever groundbreaking experiment that will change how all of us see our homes.

And of course, a big shout out to the sponsors for Home Diagnosis TV - this wouldn't be possible without your generous support for industry change. 

Until next time! 

Digest - The IEA Future Of Cooling Report: Opportunities For Energy Efficient Air Conditioning by Positive Energy

Greetings building science enthusiasts! 

The IEA put out a pretty fantastic report recently on The Future Of Cooling, outlining opportunities for energy efficient air conditioning systems. The perspective of this report is excellent and the International Energy Agency has taken on a daunting task of amassing some serious data and predictive analytics to bring these findings to light. We've done our best to help you digest some of the big take aways. 

Growing demand for air conditioners is one of the most critical blind spots in today’s energy debate. Setting higher efficiency standards for cooling is one of the easiest steps governments can take to reduce the need for new power plants, cut emissions and reduce costs at the same time.
— Fatih Birol, Executive Director, IEA
Growing demand for air conditioners is one of the most critical blind spots in today's energy debate. Setting higher efficiency standards for cooling is one of the easiest steps governments can take to reduce the need for new power plants, cut emissions and reduce costs at the same time.

Highlights From The Report

The growing use of air conditioning systems in homes around the world will be one of the top drivers of global electricity demand over the next three decades. In the IEA report – “The Future of Cooling” – they're calling the potentiality for the sharp rise in demand without new codes to effectively handle the raw energy inputs and outputs, that the the world will face a “cold crunch” from the growth in cooling demand. The logic makes sense - if air conditioners are a dominant energy user in homes and the market share grows vastly, we run into the strange trap wherein the planet is getting hotter so we try to cool down our indoor spaces, in effect adding to the warming trends.

 Air conditioning today is concentrated in a small number of countries, but AC sales are rising rapidly in emerging economies.  Courtesy of IEA

Air conditioning today is concentrated in a small number of countries, but AC sales are rising rapidly in emerging economies. Courtesy of IEA

If as the report suggests, global energy demand from air conditioners is expected to roughly triple by 2050, this would require new electricity capacity to become equivalent to the combined current electricity capacity of the United States, the EU and Japan. This is a significant growth and one that presents a real challenge to climate solutions. And on the economic front, there will be significant movement in industry creation/expansion in underdeveloped places across the world. The global stock of air conditioners in buildings will grow to 5.6 billion by 2050, up from 1.6 billion today – which amounts to 10 new ACs sold every second for the next 30 years. 

Keep in mind that none of this is specific to any type of air conditioning equipment, but assuming that the majority of growth is happening in markets where ductless VRF units (mini splits) are commonplace, we could reasonably expect to see more expansion of that technology rather than the less energy-sensible unitary compressors. But even still, there's a lot of energy infrastructure necessary to 

 The world faces a ‘cold crunch.’ By 2050, around 2/3 of the world’s households could have an air conditioner. China, India and Indonesia will together account for half of the total number.

The world faces a ‘cold crunch.’ By 2050, around 2/3 of the world’s households could have an air conditioner. China, India and Indonesia will together account for half of the total number.

Using air conditioners and electric fans to stay cool already accounts for about a fifth of the total electricity used in buildings around the world – or 10% of all global electricity consumption today. But as incomes and living standards improve in many developing countries, the growth in AC demand in hotter regions is set to soar. AC use is expected to be the second-largest source of global electricity demand growth after the industry sector, and the strongest driver for buildings by 2050.

 Cooling is the fastest growing use of energy in buildings. Without action to address energy efficiency, energy demand for space cooling will more than triple by 2050 – consuming as much electricity as all of China and India today.

Cooling is the fastest growing use of energy in buildings. Without action to address energy efficiency, energy demand for space cooling will more than triple by 2050 – consuming as much electricity as all of China and India today.

Supplying power to HVAC units at a scale like this comes with substantial economic costs and environmental/ecological implications. The variability of unit efficiency and market uptake of more energy sensible units is certainly an issue. For example, HVAC units sold in the Japanese and the European markets are generally in the range of 25% more efficient than those sold in the United States and Chinese markets. Base line efficiency improvements, or codification could cut the energy growth from HVAC demand in half through more stringent mandatory energy performance standards.

 The problem is, today's consumers are not buying the most efficient ACs. The average efficiency of air conditioners sold today is less than half of what is typically available on the shelves – and one third of best available technology.

The problem is, today's consumers are not buying the most efficient ACs. The average efficiency of air conditioners sold today is less than half of what is typically available on the shelves – and one third of best available technology.

The report outlines what they view as key policy actions. In what they've called an Efficient Cooling Scenario, which was designed to be compatible with the goals of the Paris Agreement (of which the U.S. is not a signing party, unfortunately), the IEA predicts that through more stringent minimum energy performance standards, the average energy capacity of the widely available HVAC units worldwide could more than double between now and 2050. The idea is that this is not only a way to curtail environmental issues, but reduce governmental spending on energy infrastructure across the globe - the saving estimates are as much as USD 2.9 trillion in investment, fuel and operating costs.

 Investing in more efficient ACs could cut future energy demand in half. The report's Efficient Cooling Scenario shows that effective policies can double average AC efficiency and reduce cooling energy demand by 45% compared to the Reference Scenario.

Investing in more efficient ACs could cut future energy demand in half. The report's Efficient Cooling Scenario shows that effective policies can double average AC efficiency and reduce cooling energy demand by 45% compared to the Reference Scenario.

The rise in cooling demand will be particularly important in the hotter regions of the world, like Austin, TX. Interestingly, this is the least well understood climate zone type in the building science disciplines, although we're in the trenches bringing awareness to the AEC community's strong need to step up its game in hot humid climates. See, for example, The Humid Climate Conference

I didn't expect this number, but the report calls out that less than 1/3 of global households own an air conditioner of any kind, which is rather staggering considering how normal it is in the southern US. They call out that in countries such as the United States and Japan, more than 90% of households have air conditioning, compared to just 8% of the 2.8 billion people living in the hottest parts of the world (often accompanied by humidity). 

The issue is particularly sensitive in countries in high growth moments, with the biggest increase happening in hot countries like India – where the share of HVAC in peak electricity load could reach 45% in 2050, up from 10% today without sensible action at a policy level. The implications are worth seriously considering when we think about the scale we're talking about.

 More efficient ACs cut CO2 emissions from space cooling in half and combined with cleaner power sources can radically reduce overall emissions. Local air pollution is also drastically cut.

More efficient ACs cut CO2 emissions from space cooling in half and combined with cleaner power sources can radically reduce overall emissions. Local air pollution is also drastically cut.

What's Next?

“The Future of Cooling” is the second IEA report that focuses on “blind spots” of the global energy system, following the “The Future of Trucks,” which was released in July 2017. The next one in this series – “The Future of Petro-Chemicals” – will examine ways to build a more sustainable petrochemical industry. It will be released in September.
— IEA Press Release

What's In Your Couch? by Positive Energy

Greetings building science enthusiasts,

As many of you already know, we're interested in indoor air quality and more broadly interested in the health impacts of the built environment. It's fundamentally changing the way we design, build, and specify. The materials we use have properties that can either help or harm the people that come into contact with them. So let's take a look today at a particularly nasty component of many materials: 

Halogenated/Brominated Flame Retardants 

What are they? 

Flame retardants are compounds added to manufactured materials, such as plastics and textiles, and surface finishes and coatings that inhibit, suppress, or delay the production of flames to prevent the spread of fire. They may be mixed with the base material (additive flame retardants) or chemically bonded to it (reactive flame retardants). Brominated and chlorianted chemicals are added to products such as televisions, computers, textiles, building materials, infant car seats, and strollers, despite a lack of evidence that they actually prevent fires. Laboratory studies show that some of these chemicals can lead to negative birth outcomes, harm the developing brain, hamper sperm development, and impair thyroid function. Numerous states have taken action on halogenated flame retardants.

We thought this video was helpful to provide some clarity:

Toxic flame retardant chemicals are saturated in the foam inside our furniture. These chemicals are linked to serious health effects and are worthless in preventing furniture fires. We need better regulation of these chemicals to address this problem.

The point of this post is pretty simple - we want to pose a simple question:

Are you specifying or using materials with brominated flame retardants?

If so, it's probably time to ask yourself why and whether there are other solutions you can offer your projects. Positive Energy doesn't necessarily have all the answers and we recognize that every situation is different, but we think we at least can point out the problem. 

If we follow Kristof's 5 Rules For A Healthy Home, we can pretty well see where this one fits: minimize indoor emissions. 

More Resources

If you're interested in more resources on chemical free materials, check out the Chemical Free Community's database.


Research Outcomes Of The Harvard Healthy Buildings Team by Positive Energy

Greetings building science enthusiasts! 

To reiterate a trend we see more and more, the overlap of the building sciences and health sciences continues to grow. Recently, Harvard University’s School of Public Health re-launched their Center for Climate, Health, and the Global Environment, introducing new partnerships and a new director for the institutional home of Dr. Joseph Allen’s Healthy Buildings initiative. They're calling themselves the Healthy Buildings Team and they're pretty deep into a research project on how today’s built environments impact the health, productivity, and well-being of the people inside. Their mission is simple, but ambitious: “improving the lives of all people, in all buildings, everywhere, every day.” 

Improving the lives of all people, in all buildings, everywhere, every day
— The Healthy Building Team Mission
 There are multiple dimensions of beauty to juggle in architecture. If you move one face, the implications can be project-wide. Start early with good principles. 

There are multiple dimensions of beauty to juggle in architecture. If you move one face, the implications can be project-wide. Start early with good principles. 

This level of focus on the importance of buildings across many outcome-based measures is becoming increasingly prevalent in design and policy discussions. The bar has been raised for architects to deliver multiple dimensions of beauty and, with the emerging research on health impacts of buildings, there will absolutely be liability associated with it. But health is really just one face of the Rubik's Cube.

Recently, The Building Science Podcast got a couple of Press Passes and went to New York City for the AIA Conference on Architecture, 2018. We had the opportunity to connect with so many thoughtful and visionary architects who want to build a better, healthier future, despite the complexities.  

One of the most thoughtful conversations we had was with Corey Squire and Tate Walker about the new Committee On The Environment's (COTE) new Toolkit, which directly deals with health impacts on buildings, as well as "other sides" of the Rubik's Cube. It's a resource-rich document that helps firms and projects of any kind measure their progress against benchmarks of sustainability without restrictive prescription pathways, while keeping outcomes at the central focus. Just take a look at the new COTE Toolkit's (listen to our podcast episode on the Toolkit to learn more) reasons that buildings matter:

COTE Top Ten Reasons Buildings Matter

  • Integration #1 - Ranking of built environment in determining happiness
  • Community 90% - % of time people spend indoors
  • Ecology 45% - Buildings as % of US greenhouse gas emissions
  • Water 80% - Buildings as % of municipal water supply
  • Economy 87% - Buildings as % of global GDP
  • Energy 75% - Buildings as % of US electricity use
  • Wellness 50% - Increase in risk of adverse health effects through poor indoor air quality
  • Resources 40% - Buildings as % of raw material use
  • Change 400% - Return on investments in natural disaster preparedness
  • Discovery 73% - Built environment % impact of on student test scores

There is a lot more that this Toolkit has to offer and we highly recommend that you take a moment to orient yourself with its contents and use them for your projects, especially if you are on the design side of the industry. It's also just the first version so any and all feedback you have for the COTE advisory board will inform and improve future versions. But just take a look at Ecology, Wellness, Integration, and Energy - all of which fit directly into the context in which we're discussing the health impacts of buildings today.

And true to the trend of overlap we mentioned earlier, we see the Harvard Healthy Buildings Team study is directly overlapping with the AIA's own design resources. Both researchers and the national organization of architects are paying attention to the impact of our professional decisions on the health of the occupants we serve. This is a big deal and we're just at the beginning. If you're young in your career, this emerging field of research will absolutely change the way you operate as a design professional going forward.

But back to the study - the Healthy Buildings team have released what we consider to be a pretty decent list that details the simple foundations of making a building healthy. Even though there's a pretty heavy commercial bias in the study, it's still applicable and sets up a really nice framework to consider these topics in broad strokes - as principles around which we can make design decisions. 

The Background

Joseph Allen Harvard School Of Public Health
The idea for the “The 9 Foundations of a Healthy Building” arose from many interactions over the past several years with real estate professionals, building owners, hospital administrators, facilities directors, homeowners, and academic colleagues. Two things stood out. First, during these discussions, we would often say, “The idea of a healthy building has been made too complicated. We know how to make buildings healthy. There are a few simple foundations.” This of course led to requests to name the foundations of a healthy building. In the ensuing discussion and debate we realized that we, the public health community, have failed to translate our research into actionable information; the richness of the public health literature was invisible to key decision-makers. Second, in these presentations and meetings we would often hearsome variation of the refrain, “Your research is very interesting, but I can’t take a scientific paper into my meeting on Monday and convince a building owner or manager to do things differently. I need a short summary.” Thus, the 9 Foundations project was born.
“The 9 Foundations of a Healthy Building” was created by a multidisciplinary team of experts from the Healthy Buildings Program at the Harvard T.H. Chan School of Public Health. You can learn more about the team and our research at www.ForHealth.org. The 9 Foundations curated summaries are designed to be a clear and actionable distillation of the core elements of healthy indoor environments. For each, we created a 2-page summary of the underlying science, fully cited back to the primary literature. These summaries are included in the following pages, along with a short guide for how to achieve each foundation. The 9 Foundations apply universally toall building types, including homes, but the supporting text focuses mainly on commercial office environments.
The 9 Foundations are the beginning of what we are calling “Building Evidence for Health” – a collection of 2-page curations of the scientific literature on key topics related to buildings and health. We began with these 9 Foundations and plan to add to this collection. As always, weare interested in improving and refining this idea, so we welcome feedback. Please write us with your ideas for topics, comments or questions. We will use your feedback and new research to update the Building Evidence for Health summaries periodically.
We hope that you find this information helpful. Our goal is to improve the lives of all people, in all buildings, everywhere, every day. We cannot do this if the knowledge generated by our research community does not reach you, the people who control, manage and occupy buildings across the world. The 9 Foundations intends to bridge this gap.

Joseph Allen, Assistant Professor of Exposure Assessment Science, Department of Environmental Health

Harvard 9 Foundations Of Healthy Home

Areas Of Focus

Obviously, all of these elements are crucial to creating a place where human beings can thrive. But there are a few of the 9 Foundations that we here at Positive Energy particularly want to bring some focus to because they are DIRECTLY affected by the work we do with architects. You're perfectly capable of checking out the rest of the list on your own, but I've digested our areas of focus below.


Panasonic ERV

Obviously ventilation is important - yet it receives such little attention in from the codification efforts in many major cities across the world. In many ways ASHRAE has led the way in normalizing ventilation with quantitative measures, but adoption is always slow and the positive effects are subsequently slow to move into the spotlight. To see a reputable research institution like Harvard take this on is a big deal. And the study lays out a pretty reasonable approach to communicate why ventilation matters and how it can impact health. 

Why Is Ventilation Important?

"Ventilation in buildings is required to bring fresh air in from outside and dilute occupant-generated pollutants (e.g., carbon dioxide) and product-generated pollutants (e.g., volatile organic compounds). If mechanically ventilated, a building’s mechanical system is designed to bring in outdoor air, filter thatair, and deliver it to occupants. Even with proper ventilation, the concentration of pollutants indoors can be higher than concentrations found outdoors. Outdoor pollutants, like PM2.5, can penetrate indoorsthrough several routes, one of which is through the mechanical system if the air stream is not properly filtered. Because people spend so much time indoors (90% or more for many people), most of a person’s exposure to outdoor air pollution may occur indoors. 

Ventilation systems also influence temperature, humidity, and air pressure. In an effort to ensure better Indoor Air Quality (IAQ) in building spaces, current ASHRAE standards require a minimum of 20 cubic feet per minute per building occupant (cfm/person). This standard, by definition, is designed to provide merely “acceptable” indoor air quality despite decades of research showing benefits ofhigher ventilation rates. In addition to specifying higher ventilation rates, improved maintenance of HVAC is required because substandard ventilation often occurs in buildings where HVAC systems are either neglected or inadequately maintained.

Air Quality

This is a topic that Positive Energy has seen the very clear need to address at every level possible. For us, we use research like this to inform our design details and strategies for the Integrated Mechanical Designs we do with residential architecture firms. And it's with very good reason -  indoor air quality is directly affected by the enclosure and the mechanical systems we implement.

Bad Air Quality

Why Is Air Quality Important? 

When IAQ is poor, occupants can experience building-related illnesses such as asthma,fatigue, irritation, and headache. Because humans spend up to 90% of their time in offices, schools, andresidences, and inhalation exposure is continuous, our largest exposure to pollutants (of both indoor and outdoor origins) occurs indoors. Materials and furnishings with low chemical emissions should be used. Vapor barriers are necessary for limiting vapor intrusion and humidity levels must be stabilized to control odors. 

How does poor indoor air quality affect human health?

Volatile organic compounds (VOCs) are a class of chemicals that are commonly associated with IAQ issues. VOCs are chemicals with a high vapor pressure that emit gas into the air and can come from building materials, consumer products, paints, personal care products, furniture, and many other products. Exposure to VOCs has been associated with everything from minor irritation of the eyes to certain forms of cancer. While extensive evidence has documented adverse respiratory health effects of outdoor air pollutants, more recent studies have shown that indoor air pollutants can have similar consequences. For example, the substantial presence of indoor ozone has been linked to irregular heartbeats and poor lung function as well as irritation to the eyes, skin, nose, and throat. Concentrations of pollutants indoors, in some instances have been shown to be twice as high as those outside (EPA). 
Exposure to indoor air pollutants have been repeatedly linked to asthma, allergies, bronchitis, and chronic obstructive pulmonary disease. Research examining indoor pollutants in the food service sector observed a positive correlation between kitchen PM, VOCs, polycyclic aromatic hydrocarbons (airpollutants produced in the process of broiling meat and burning fuel) and kidney inflammation. Allergic reactions are also commonly associated with exposure to indoor air pollutants, among both sensitive and non-sensitive individuals.

There is so much more to say on this topic so please dive into our podcast, as well as the resources laid out in this study to begin working out how you'll tackle the challenge of designing good indoor air quality for your clients. 

Thermal Health

Thermal Comfort

By this point, you're probably starting to see why we like this study so much. Their categories line up so well with the critical design criteria we have been working on for the last decade. And thermal health and comfort have been a driving force in the success of bringing thoughtful and robust mechanical designs to residential projects since our nascent years as a business.

What is thermal health and why does it matter?

Traditionally, the focus in the built environmenthas been on thermal comfort, which is defined as “the condition of mind that expresses satisfaction with thethermal environment and is assessed by subjective evaluation”. Thermal comfort is influenced by objectivefactors like air temperature, mean radiant temperature, air speed, and humidity, as well as personal factors like metabolic activity level and thermal insulation from clothing. 
A model developed in the 1970s by Ole Fanger, and still used today, provides a means of predicting if an occupant in a space will besatisfied in terms of thermal comfort based on these parameters. This model is the basis for the current standard that governs thermal comfort in buildings, and its stated goal is to provide an environmentwhere at least 80% of people will be satisfied. Many studies have shown that when thermal comfort parameters fall outside of theseacceptable ranges there is a significant impact on performance in offices, schools, and homes. But the impacts of thermal conditions extend beyond comfort. Temperature and humidity can also have a drastic effect on health, as evidenced by the heat wave in France in 2003, which claimed nearly 15,000 lives. In the face of rising global temperatures, these events will become more frequent. As such, we propose the use of the term “thermal health” to highlight all the health effects of thermal conditions.

There's not really much context we need to provide here. Let's continue:

How do thermal conditions impact the body?

Thermoregulation of the body is controlled by a homeostatic system that responds to external thermal cuesand internal hormonal cues to maintain core body temperature at approximately 37° Celsius. This is primarily accomplished by dilating or constricting blood vessels, which can change how fast heat dissipates from the body through convection and conduction, and by other thermoeffectors like sweating and shivering. Humidity influences the evaporative cooling mechanisms of our physiology. That is, if the humidity is too high, and theair more saturated, our body has a reduced capacity to cool itself through sweating.

The report has more great info on mechanical systems and the health impacts, which I highly recommend you read. All to say that thermal health is an extremely important and something that every project should be focused on. Of course, we're a bit biased since we're in the hot humid south and thermal conditions are important to staying sane in the summers 😉. 


We know that we have a strong bias toward talking about humidity and moisture in homes because we see the lived reality of mistakes made every day. Austin, TX is a hot and humid place and those two factors left unchecked can prove incredibly problematic for a building and result in health issues, higher energy use, an potentially even lawsuits.

Indoor Humidity

Why does building moisture matter?

The scope of water damage and subsequent exposures is quite extensive; studies conducted acrossEurope, Canada, and the United States have observed mold, mildew, or water damage in up to 36% of homes.

How does moisture impact the indoor environment?

Entrance of water into damaged, poorly designed, and improperly maintained buildings has been identified as themain source of building-related illness from mold exposure in an Occupational Safety & Health Administration (OSHA)review of over 120,000 indoor air quality documents published between 1994 and 2001. Common sources of moisture in buildings can include: leaks from plumbing, roofs, and windows; flooding; condensation on cold surfaces (e.g., poorly insulated walls and windows, non-insulated cold water pipes, toilets); poorly maintained drain pans; or wet foundations from landscaping or gutters that direct water into and around a building. Secondary sources of moisture include water vapor from inadequately vented kitchens, showers, or combustion appliances. Excessive moisture collection in buildings creates favorable conditions for mold growth, which, if left unchecked, can destroy the surfaces they grow on. Moisture and mold growth can accumulate in materials such as wallboard and carpeting without being noticed even in buildings with good housekeeping and maintenance.
In buildings, molds reproduce through the accumulation of spores, tiny cells that float continuously throughindoor and outdoor air.6 When mold spores encounter a moist surface indoors, they can begin to grow on and digest their host surface. Areas typically exposed to mold in buildings are on carpets, ceiling tiles, insulation materials, wood, areas behind wallpaper, or in HVAC systems. These fungi can producea number of irritating substances, including spores and volatile organic compounds (VOCs). The latter substances are responsible for musty odor, and can contribute to adverse health effects of individuals exposed. The most common indoor molds are cladosporium, penicillium, alternaria, and aspergillus.

It's no longer just Kristof telling you this is a problem on the podcast, it's The Healthy Buildings Team at Harvard telling you this is a real problem. Be diligent in your strategies, be fastidious in your detailing, and make sure you're assembling the right project team to pull off the right level of quality. 

Dust & Pests

Moreso than from the maintenance and cleaning perspective in a commercial building, we think about dust and pests from the perspective of how the building's enclosure system is preventatively working and how the mechanical system's filtration strategy is working to reduce airborne particulates. But there's some good stuff here in the study worth reading. 

dust mites

What is the significance of dust to human health?

Many contaminants reside in dust and lead to exposure in three different ways: 1) inhalation ofresuspended dust, 2) direct dermal absorption, or 3) ingestion from hand-to-mouth behaviors. For the first pathway, dust (also called particles) on a person’s clothes, furniture, and other upholstered materials is continuously suspended and resuspended through normal activities like walking through the house, vacuuming, or folding laundry. In fact, people have a personal “cloud” of resuspended dust around them as they go about daily activities, not unlike the famous “Pigpen” character in the Charlie Brown cartoon. When the particles are resuspended, exposure can occur through inhalation. For the second pathway, chemicals in air and dust can partition out of the air and dust onto the skin and enter our bodies via dermal absorption. The third pathway, sometimes referred to as “incidental dust ingestion,” occurs when dirt and dust accumulate on our hands and are transfered to food or are ingested directly through hand to mouth contact. It is estimated that adults ingest up to 100 mg of house dust per day and children up to 200 mg per day.  Higher ingestion rates in children are due to the greater amount of time they spend in contactwith the floor and other surfaces, and higher frequency of hand to mouth behavior.
This mass of dust that enters our body every day is relevant to human health because dust acts as a reservoir or sink for a variety of potentially harmful agents – outdoor particles that penetrate indoors, viruses, bacteria, chemicals, allergens (pets, mites, mold spores, pollen),building materials, dander, fabric fibers, and paint flakes that containlead. Some of these agents (such as viruses) may only exist in dust for a few hours, while others may remain in the dust for decades. Indoor dust is the primary route of exposure for lead from lead-based paint,which can accumulate in dust from flaked paint or dirt tracked in fromoutdoors. Unlike chemicals in the air, chemicals in dust can continue to expose occupants long after the sources have been removed. This is of particular concern for Persistent Organic Pollutant (POPs), a name given to chemicals that are resistant to breakdown in the environment, and thus they can persist in the dust for many years.  For example, flame retardant chemicals that are used in consumer products migrate out of those products into air and dust. Studies have documented that the amount of chemical that is present in indoor dust can be directly correlated with amount of chemical found in the blood of people living and working in those environments, providing quantitative evidence of the significant role of indoor dust in overall chemical exposure.

It's no surprise to hear this reiterated through their research. And it's absolutely all the more reason to think deeply about where dust is coming from and how to capture it. To continue the topic from a slightly different perspective, let's take a look at pests as they might be mitigated by well thought out mechanical systems. 

What is the significance of pests to human health?

The primary concern from pests and domestic animals is that they introduce allergens to the indoor environment which can cause an immune response in adults and children. The most relevant sources formost indoor locations are: dust mites, cockroaches, mice, rats, cats and dogs. 
Dust mites are microscopic pests that feed on shedded human and animal skin cells, typically burrowing in bedding, mattresses, and furniture upholstery. While dust mites do not bite or sting, their feces and body parts create a harmful allergen (Der p1) that can dramatically impact human health. Mites have been associated with asthma, immune responses such as allergic rhinitis (hay fever), and allergic reactions ranging from mild symptoms like runny nose and watery eyes, to more severe responses such as asthmaattacks. Among asthmatic children, the rate of dust mite allergen sensitivity can range from 48-63%, and high allergen exposure among these individuals increases their risk of hospital admission.11 In a study conducted across the United States, four out of every five homes had detectable dust mite allergens in at least one bed. 


Again, please read the full report and get into the details of the research - especially the elements we didn't touch on here. They're deserving of exploration as well. 

And now look at what's being presented here. It's no stretch to see how crucial it is that we begin thinking of buildings as vehicles of health outcomes. The decisions we make in design and construction can either support good health outcomes or cause negative health outcomes. We should not take that responsibility lightly.

When teams from top-tier research institutions, like Harvard, are pointing to the relationship between the built environment and health outcomes in our global society, it's time to stop pretending that the notion of healthy buildings is a fad that will fade out. We are at the pivot point in our industry and we are faced with the choice to either be leaders with a clean conscience or wait until the codes make us so we don't have to make the effort to figure it out before we have to. 

In our minds at Positive Energy, the decision is very clear. Let your ethics be your guide.

Project Contributors 

The 9 Foundations of a Healthy Building © 2017


For more information:
Joseph G. Allen
Assistant Professor
Harvard T.H. Chan School of Public Health


Duct Leakage? New Press In The Journal Of Light Construction by Positive Energy

Check out the latest press Positive Energy's getting in the Journal Of Light Construction. Senior Editor & Author Ted Cushman explores the intricacies of high performance HVAC design, installation, and performance testing - and he explored it with us on one of our project collaborations with Matt Risinger's company Risinger & Co

"A home’s air conditioning system, Kristof Irwin, P.E., likes to say, is like the lungs of the building: As the home’s air supply, the HVAC’s proper functioning is vital. And while the air conditioner itself will likely be replaced in 15 or 20 years (and can certainly be repaired any time), the ductwork is different, Irwin points out: Buried in the ceilings and walls, many duct runs are inaccessible. Once installed, ductwork is what it is—and it may have to serve for the lifetime of the building. As Irwin puts it, “The ducts are infrastructure.”
Irwin is the founder and principal of Positive Energy, in Austin, Texas. Along with providing other services, his company designs high-performance HVAC systems, typically specifying high-efficiency variable-speed compressors and air handlers, paired with dedicated dehumidification and ventilation equipment. Irwin uses the industry standard ACCA Manual J to estimate heating and cooling loads; ACCA Manual D is used to specify the building’s ductwork."
"In a brand-new home, Sean Harris says, a by-the-book design should perform as intended—as long as it’s installed correctly. Anybody can make a mistake, though, he notes—and in any case, last-minute changes that affect the ductwork are common. “Very rarely does a job go exactly as planned,” Harris notes; for this project, Positive Energy had to modify the distribution systems for several zones after a preliminary walk-through, to adjust to changes in structural framing and truss configurations. And since the systems can’t be easily modified once drywall is complete, it’s important to verify the effect of the changes while ducts are still accessible."
 The drawing above, which JLC adapted from one of our design renderings, shows the anatomy of a typical duct system connected to a high-performance air conditioner. You'll see we specified dedicated dehumidifying equipment, a ducted fresh air supply, and bath exhaust fan details in addition to the air conditioner and its ducts. The design calls for metal ducts, except for short runs of flex duct at registers to reduce noise. If the design is correctly installed, testing should not reveal any trouble.

The drawing above, which JLC adapted from one of our design renderings, shows the anatomy of a typical duct system connected to a high-performance air conditioner. You'll see we specified dedicated dehumidifying equipment, a ducted fresh air supply, and bath exhaust fan details in addition to the air conditioner and its ducts. The design calls for metal ducts, except for short runs of flex duct at registers to reduce noise. If the design is correctly installed, testing should not reveal any trouble.

“In our industry,” says Harris, “there are still some people who don’t understand how duct design works. They think that a rule of thumb from the 1980s is still how it’s done. But that’s not the case. For airflows, fluid dynamics works, and there are simple software tools out there that accurately predict how much air you are going to get out of that duct. And when it is installed exactly as we design it, we actually get that delivered performance.”

Using New Tech - Airzone Damper System by Tel Rosipal

Greetings building science enthusiasts! 

Welcome back to the old blog-a-roo for a few thoughts. As you probably already know, we regularly experiment in our office with technologies to vet products for our mechanical designs. Interestingly, we found a Spanish air side zoning product called Air Zone and the early results are positive. 



It's an age old story: using traditional zoning design allows the one room with the thermostat to have all the control when it comes to thermal comfort.  Then the fighting over the setpoint of the thermostat begins. Airzone has developed a system that allows for different setpoints to be achieved in different rooms using zoning technology and smart controllers.  

We used One Zone VRF system to couple with the Mitsubishi PUMY unit we have in the office. In short, one existing compact ducted VRF system already separated into several zones. The idea is to use Airzone to allow for independent set points for each room.  

What exactly is Airzone?

Airzone is a zoning system that communicates with a VRF system's control board to provide set-point independence. Each zone has its own damper controller and thermostat select set points.

By using automated dampers to regulate air flow from the VRF system into each of the zones, the central controller communicates with the VRF system in lieu of the manufacturers thermostat port. If a zone controller is calling for more air flow to satisfy setpoint then the damper will open up and allow more air to cool the zone. Each board can handle up to ten zones. 

Overall the system was accessible and pretty easy to understand and the company offers strong support when questions come up. Once the dampers are installed they just need to be connected to each of their respective controllers and connected to the central control board. Airzone uses simple standard ports for easy installation and connections. From there the control board needs to be connected to the internet to use the wireless smart controllers or the app. Simple installation and implementation. The gallery below shows the control board, damper with wired connections, and one of the Airzone Think controllers that are being used in the office.

We'll report back with some more data-intensive reporting on the system and maybe even a podcast episode on the tech. Until then, stay cool out there. It's hot here in Texas. 

The Building Science Podcast Reviews by Positive Energy

You know, it's kind of funny after these last 4 years of creating and developing and maintaining this show - none of us thought it would go anywhere when we started it and we just kind of thought it'd be a fun thing to do. Fast forward to today and we've got a whole bunch of you out there listening, giving us ideas, and we've interviewed some of the best thinkers in the business. It's pretty awesome.

And now we're asking for your help. It's not a big favor to ask, we promise. 

As with any podcast, our show lives and dies by reviews. Without reviews on the podcasting app (mobile), iTunes (desktop), or on Stitcher, we lose placement in the search results and our audience doesn't expand. Today we're simply asking you to take a look at what other folks have said and consider leaving us a review. 

When we took a look through some of the feedback that listeners have given us, we were humbled by how positive their words are. Thank you to all of you who listen and review!

Here's What Folks Are Saying

Leave A Review

If you haven't left us a review yet, please consider it. We love any and all feedback - after all, this show is fundamentally about you getting something useful and inspiring out of it. 

Answering Your Burning Questions At The Humid Climate Conference by Positive Energy

Kristof and Miguel will be on the Humid Climate Conference scene recording lots of great content for The Building Science Podcast and they want to hear what questions you want answered. They'll be hanging out with Joe Lstiburek, Lew Harriman, Jonathan Bean, Kimberly Lewellyn, Andy Äsk, Matthew Tanteri, Claudette Reichel, ad infinitum. Brain juice to the max, y'all. 

Don't miss out! 

How To Ask Your Question

  1. Leave it in a comment on this blog post. We'll check back daily to see what you've got to say. 

  2. Tweet at us with the hashtag #HCC2018. You can find us at @bldgscienceatx

  3. Email us at podcast@positiveenergy.pro

Live Streaming

If you can't make it to the conference, but still want to see the talks, there are live stream tickets available for purchase at the Humid Climate Conference website. It's going to be a good one. 


Kristof's Recent Interview With The Journal Of Light Construction by Positive Energy

Greetings building science nerds,

Thanks for stopping by our little bloggy corner of the web.

As you could reasonably expect, when someone calls Kristof and wants to talk about building science, we avoid the norms. Instead of talking about assemblies or materials and ratings, we go straight to talking about human health and how the building serves it. And that's exactly what happened when the Journal of Light Construction's Senior Editor, Ted Cushman, called to talk with Kristof for his recently published article, "Controlling Humidity in Warm Climates.

What is the main output of your house? It’s healthy, productive human beings. The main output is you. So all the stuff we do around buildings really should be around you. And the main thing I need to do for you is to deliver healthy air for you to breathe. In building science, it might be safer and friendlier to talk about moisture accumulation in materials, and ‘should we do a vapor retarder,’ etc.—but it’s much more important to talk about upper respiratory infections, asthma, and sleep apnea.
— Kristof Irwin, P.E. Mech. Eng., Co-founder of Positive Energy

Check out the article for yourself. It's a good read and has some pretty pictures of machines made by our friends over at UltraAire Dehumidifiers. And if you haven't yet, check out our podcast. We talk plenty about the overlap of the health sciences and the building sciences. There's a lot to talk about! 



Positive Energy Press Updates by Positive Energy

Positive Energy has been busier than ever with new design work, but we've also got some great projects finally built and getting some remarkable recognition. We're so proud to be involved with the great partners we have. 

The Constant Springs Residence

Alterstudio Architecture

Our clients partner with us to manage the complexity of delivering comfortable, healthy spaces in their projects. And we're proud to work with alterstudio on their residential work because they're a firm who cares deeply about process and the outcomes they deliver for the homeowner. Our communications are smooth and the more we work together, the easier it is to anticipate one another's needs. To-date, we've designed integrated mechanical systems for dozens of projects together. 

Alterstudio focuses its attention on the relationship between the material facts of architecture and the social occasions it shelters and invites.  The work is rooted in deep-seated virtues of architecture – generous space making, shrewd manipulation of day lighting, and meticulous attention to detail. The heightening of direct human experience and the framing of the complex circumstances of their situations are at the core of each project.

We think they're absolutely fantastic and to play a small role in helping deliver their vision is such a rich experience and rewarding endeavor. 

I have been working in custom residential architecture in Austin, Texas for over 15 years. Our firm prides itself on thorough attention to detail, and to the resolution of technical issues especially as they relate to the broader experience of the architecture. For many years I had sought out a partner that could work with us on the integration of HVAC systems. We tried everything: working with design/build installers in the design phase, subcontracting with mechanical engineers whose specialty was obviously commercial, and reaching out to companies outside of Austin that claimed to specialize in residential HVAC. The results ranged from modest regrets to full on disappointment. When we came across Positive Energy, we finally felt like we had a dedicated and knowledgable team member that would help us take our projects to another level of resolution. It has truly been a successful partnership.
— Ernesto Cragnolino, FAIA

If you're in Austin and came out to the last AIA Homes Tour, you were lucky enough to walk around in their Constant Springs Residence for which we designed mechanical systems. The project has received quite a lot of attention lately, most notably the cover of the most recent edition of Dwell Magazine. Structural coordination and aesthetic integration was key on this project. There was no stone left unturned in detailing. 

Photos Of Magazine: Creede Fitch

Architectural Photos: Casey Dunn

Alterstudio also earned Luxe Magazine's RED Award for AUSTIN + SAN ANTONIO Regional Winner, Contemporary Architecture. Moral of the story, we're very proud of our work together and can't wait to see what these incredible and thoughtful colleagues of ours keep cooking up. We'll keep you posted on future collaborations. 

Haskell Health House

Jen Weaver, Weaver Buildings

Jen Weaver is an architect and developer passionate about the market realization of high-performance buildings. She actively participates in Urban Land Institute, particularly the FutureBuild Committee, and is a member of United States Green Building Council. Jen currently attends the University of Southern California Price School of Public Policy seeking a Master of Real Estate Development. Her research describes the potentials of greenhouse gas capture and Clean Air Infrastructure Real Estate futures.

The Haskell Health House is an urban garden home steps from Lady Bird Lake, Austin, Texas. Thoughtful interior spaces fill the home with over 1100 sq ft of landscaped living featuring an outdoor kitchen, dining space, cocktail lounge, master screened porch and a roof deck with lake views. We had a lot of fun designing with Jen on this project, thinking deeply about indoor air quality and thermal comfort.

Most recently her project was featured in a spread by Green Building Magazine Taiwan

 Photo: Atelier Wong

Photo: Atelier Wong

Architectural Photos: Twist Tours

Prairie View A&M University Team Grand Winner at Race to Zero Student Design Competition

We're proud to announce to our readers that the student team from Prairie View A&M University, under the guidance of their professor Shelly Pottorf took home a few major awards from this year's Race to Zero Student Design Competition. Turns out, this wasn't the Prairie View A&M team's first rodeo. They're a really sharp bunch. 

The Race to Zero is a U.S. Department of Energy competition that inspires collegiate students to become the next generation of building science professionals through a design challenge for zero energy ready buildings. Students become part of a new leadership movement to achieve truly sustainable buildings. The Race to Zero is formulated to advance and enhance building science curriculum in universities. 

Through this competition, future architects, engineers, construction managers, and entrepreneurs will gain the skills and experience to start careers in clean energy and generate creative solutions to real-world problems. The team from Prairie View A&M turned out to be the cream of the crop this year, taking home first place not only their division contest in Urban Single-Family Housing Contest, but also the Grand Award for the entire competition. We are SO proud of their work and dedication to the project. 

We worked with the Prairie View A&M team to help bring their vision to life in a functional way. We advised the team on an array of topics - systems thinking, design thinking, thermodynamics, mechanical design, structural/mechanical coordination, enclosure detailing, and we provided mechanical and hot water design work for their project. 

 Photo: Michael Walker's iPhone

Photo: Michael Walker's iPhone

Did You Know The University Of Texas School of Architecture Has A Thermal Lab? by Positive Energy

We got to check it out and it's pretty impressive. We may even have recorded a podcast episode with Steve Bourne, who is one of the chief scientists in that lab. Who knows. All we can say for now is that it's a very comfortable place to be. 


Why Do We Keep Building And Buying Homes That Don't Serve Us? by Positive Energy

Greetings building science enthusiasts,

Let's talk about food for a minute. The thought of eating pesticides reminds us that our bodies are subject to environmental exposures that we'd like to avoid. So to solve the problem, we've decided that organic food makes a lot of sense.

And this fact really is amazing.

We live in one of the most brilliant and connected times in the history of human beings. With relative ease, most of us have access to high quality food in well stocked grocery stores. And in those stores, we can even gain insight into where the food came from, whether it was grown in an ecologically sound way, and whether or not it participated in a supply chain that involved fair trade and ethically sound transportation.

What a luxury! 

For the vast majority of its history, agriculture can be described as having been organic; only during the 20th century was a large supply of new products, generally deemed not organic, introduced into food production. The organic farming movement arose in the 1940s in response to the industrialization of agriculture.

And now It's become the norm - for those who want to purchase food conscientiously, you're more empowered to do so than ever before. And there's good reason to want to buy food this way. Again, the thought of eating pesticides reminds us that our bodies are subject to environmental exposures that we'd like to avoid. We know that chemically intensive farming is not sustainable for the very land that grows the food. The list goes on and on. The bottom line is that better food equals better living for everyone. 


So why doesn't our society treat homes the same way? Why are we generally content on allowing, what constitutes for most the largest financial transaction in one's life, to be completely unknown to us? 

Well, it's got a history, especially in the US. Around the same time organic farming was getting off the ground, just after World War II, suburban sprawl began with developments like Levittown. Not only were developments like this codifying racist housing policies, but they were also tearing at the fabric of quality building processes. Levitt envisioned Henry Ford's assembly line being able to build homes faster than anyone else. He had dollar signs in his eyes and had no notion that he'd be creating boxes for people to live unhealthy lives for generations to come. 

Any damn fool can build homes. What counts is how many you can sell for how little.
— - William Levitt

This Zeitgeist lives on today and is evidenced in almost every single growing city in America. The values that have been, for generations, instilled into the construction industry are centered on first cost and speedy delivery. It's a baton-hand-off, everyone passing on the liability to the next person down the chain.

And so we've grown to assume that the product we're getting is the best. It's become part of our vernacular through real estate sales with concepts like a "starter home." We think, "well it looks like a house and it has that tile I like" so we buy it. But there's still some part of our brain that recognizes there's more that we don't know about the house, but it gets put on the back burner. And as the political economy changed in the early aughts, many of us began to value the illusory "energy efficiency" that marketers exploited to give a sense of added value, but we rarely experience a truly well designed and built home. Even fewer still know how to assess the air quality and thermal comfort considerations that went into our home's construction. 

It's a tragic reality. But why does it happen? 

Consumers don't know and so they don't ask for it - we've been conditioned not to. But consumer behavior is something that changes through time. We saw in the "green building" movement, a glimmer of something new. And now that we're gaining knowledge about the negative impacts of poor air quality and indoor pollutants, it's only a matter of time before your home's health score becomes a regular part of the list of factors that determine whether you'd buy a home or not.

The question is not the inevitability of better homes. It will definitely happen on a long enough timeline. The question is whether or not you find the current practices acceptable and whether you're ready to start asking for something better. 

Just like organic produce, there are a lot of good reasons to ask for better homes. We know that elevated humidity levels in indoor environments are causally related to developmental asthma in kids. We know that elevated indoor CO2 levels can cause cognitive disfunction. We know that phthalates and VOCs are known endocrine disrupting chemicals - and they're literally all over your house. We know that designing better humidity control and ventilation control systems inherently improves the resiliency and ecology of a home. The list goes on and on. The bottom line is that better homes equals better living for everyone.


Mold is just the tip of the iceberg...

...when it comes to problems that occur in poorly designed and built homes. The full microbiome in our indoor spaces consists of bacteria, protozoa, archaea, and a whole host of other particulates, dust mites, and tiny invisible things that are directly interacting with your physiology.

We have to stop waiting for someone else to ask for it. The problem doesn't go away just by avoiding it or pretending it's not a big deal. If you're an architect, hire good consultants. If you're a builder, advocate for good consultants. If you're an HVAC installer, distinguish yourself by knowing better systems. If you're a homeowner, don't settle for "well this is just how it's done." 

So what are you waiting for?

Whether you're a professional in the industry or someone looking to purchase a home, you should be asking for better options. The technology to make it happen isn't the problem - there are plenty of amazing products out there. We fundamentally need to start asking the industry to pay attention to human health (meaning you and your family's health) so that the outdated processes and thinking changes.

An error does not become truth by reason of multiplied propagation, nor does truth become error because nobody sees it. Truth stands, even if there be no public support. It is self sustained.
— Mahatma Gandhi, Young India 1924-1926 (1927)



Breathing: The Good, The Bad, & The Funky by Positive Energy

Greetings building science enthusiasts! 

Thanks for joining me out on the range here to visit the ole family blog and help me wrangle up a herd of thought cows... I seriously need to get better at opening lines. 

I'm here to do a bit of a recap of a fantastic article that was just posted on The Royal Society of Chemistry's site called Every Breath You Take. If you've got time, definitely give it a read. It's got some quality analysis and framework to help us think about and relate to indoor air quality in homes. For those who are less inclined to read an entire article, here's the Positive Energy's Digest version. 

 Source: Sam Falconer/Debut Art

Source: Sam Falconer/Debut Art

Indoor Air Pollution 

Positive Energy has taken particular interest in the topic of indoor air quality as the scientific community is increasingly pointing to negative health outcomes deriving from indoor exposure to pollutants. This is particularly alarming as we've learned from The National Human Activity Pattern Survey (NHAPS): A Resource for Assessing Exposure to Environmental Pollutants that we spend 90% of our time indoors. Even more remarkably, 70% of your time is spent in your home. 

We need to be thinking about the kinds of exposure we're experiencing in homes! 

Indoor air is a dominant exposure for humans. More than half the body’s intake during a lifetime is air inhaled in the home. Thus, most illnesses related to environmental exposures stem from indoor air exposure.
— Sundell, J. (2004), On the history of indoor air quality and health. Indoor Air, 14: 51–58. doi:10.1111/j.1600-0668.2004.00273.x

How Do We Know?

The article takes a light touch approach to looking at how we know what we know about indoor air quality. It turns out that there are some really fascinating and meaningful studies and meta-studies that are going to seriously impact the way we think about indoor spaces. Scientists are studying how to measure the air and what's in it and they're studying how different exposures cause reactivity with other surfaces (including how pollutants get into our bodies, which isn't just through the lungs!). Why is that important? Well just take a look: 

The indoor environment has a lot more surface material per volume of air than an urban air basin and that translates to a much larger importance indoors of surface-associated processes.

With so much surface area for pollutants to react, there are serious health implications. There are pollutants and then there are pollutants that interact with other chemicals and become unknown and unstable pollutants... Seriously.  Add to this that each time we cook, we're creating a whole microscopic world of combustion particulates and it's a doozy! 

That's why it's so crucial that this is getting research attention. These data will literally support groups like ASHRAE as they endeavor to understand and recommend better ventilation standards, filtration standards, and deal with related thermal comfort potentiality. It's a big deal. 

The Takeaway

The time has come for us to pay attention to indoor air quality. Scientists and researchers already are. It's only a matter of time before these findings affect the laws that dictate what we're allowed to design and build, but we think we can do better already. Pay attention. Incorporate this into your practice! 

We can affect the quality of the air around us in a multitude of ways; from what products we clean with, to what fragrances we wear, to what and how we cook and whether or not we smoke or burn candles. ‘We want people to recognise that they are living in a box; any chemicals or combustion products that released into the box are in there with you. It doesn’t take a lot of mass emitted to make a high concentration in the air in your home,’ says Singer. ‘We recommend people start with the basics of using products that have less toxic chemicals, avoid excessive moisture and make sure their combustion appliances are vented.’

Thanks for reading! See you next time. 

BEC: Austin Speaker Luncheon - Indoor Air Quality by Positive Energy

 Dr. Richard L. Corsi, Ph.D., P.E. 

Dr. Richard L. Corsi, Ph.D., P.E. 

December 6, 2017 - 12:00pm - 1:00pm

Join BEC for their final meeting of the year, as they focus on indoor air quality with a presentation lead by Dr. Richard L. Corsi.

Richard L. Corsi, Ph.D., P.E.

Dr. Richard L. Corsi joined the faculty of the Department of Civil, Architectural and Environmental Engineering (CAEE) at the University of Texas at Austin (UT Austin) in 1994, after several years on the faculty of the University of Guelph in Ontario Canada.  He is the Joe J. King Chair in Engineering #2 at UT Austin, and served as Chair of the Department of CAEE at UT Austin from 2013 to 2017. Dr. Corsi received his B.S. degree in Environmental Resources Engineering from Humboldt State University in 1983, where he was honored as a Distinguished Alumnus in 2006.  He received his M.S. and Ph.D. degrees from the University of California at Davis in 1985 and 1989, respectively, and was honored as a Distinguished Alumnus of the College of Engineering there in 2016. Dr. Corsi’s research focuses on indoor air quality, particularly on sources, fate, occupant exposure, and control of pollutants of both indoor and outdoor origin.  In recent years his team has focused on indoor oxidation chemistry, including the concept of passive removal materials to control unwanted chemistry in buildings.  Dr. Corsi has served as PI on over 75 funded research projects over 27 years and has supervised 20 Ph.D. and over 50 M.S. students. Dr. Corsi teaches courses on indoor air quality at both the undergraduate and graduate levels. In 2016 he was honored with election to the Academy of Distinguished Teachers, an honor bestowed on 5% of faculty at the University of Texas at Austin.  He also received a prestigious Regents Outstanding Teaching Award for the entire University of Texas System. Most importantly, Dr. Corsi is human dad to Chloe, the world’s most wonderful Australian Cattle Dog.


Austin is an interdisciplinary organization that promotes the exchange of information on building enclosures and related science specific to the climate of Central Texas.


Architects, engineers, contractors, building owners, consultants, facility managers, code officials, educators, manufacturers, and those with a stake in building enclosure performance

Exchange of information:  

Discussion, training, education, outreach, and awareness

Building enclosures and related science: 

Energy-efficiency, moisture control, indoor air quality, longevity, and durability

2017 BEC: Austin Committee Chairs:

Kristof Irwin, PE
Amy Gelsone, AIA

BEC: Austin typically meets the first Wednesday of each month from 12-1pm.


AIA Austin
801 W 12th St
Austin,  TX 78701


Indoor Air Quality Best Practices In Post-Construction Environments by Positive Energy

Greetings building science enthusiasts,

Miguel here again to throw some mind spaghetti at the wall of the internet to see what sticks (I've got to get better at opening lines).

We know that IAQ is such an important consideration in design and construction. Essentially, if we ignore it, we're ignoring the health and well-being of the occupant, which is insane. Why build something if it's going to harm the person who will live or work there?  After all we spend 70% of our lives inside our homes and given what we know about how the human body works, the quality of the air we breathe in our homes will affect the health of our families. 

Indoor air is a dominant exposure for humans. More than half the body’s intake during a lifetime is air inhaled in the home. Thus, most illnesses related to environmental exposures stem from indoor air exposure… Main environmental issues today are outdoor air quality, energy use, and sustainable buildings, but not indoor air quality… In developing regions indoor unvented burning of biomass for cooking is the cause of at least 2,000,000 deaths a year (mainly women and children), and in the developed world IAQ is the main cause of allergies, other hypersensitivity reactions, airway infections, and cancers.
— Sundell, J. (2004), On the history of indoor air quality and health. Indoor Air
indoor air quality asthma

Nothing like a quote with some weight behind it to kick off a blog post. There is a LOT to be said about good practices for IAQ in spaces across their lifecycles, but today I want to focus on a few points and a few basic actions make it fairly simple to improve IAQ.

Phase 1: Post-Construction Building-Flush 

During this phase, the dominant pollutant sources are within the conditioned volume of the home. Pollutant sources are part of the home - predominantly surface finishes, adhesives and sealants. Obviously, it behooves us to think through what products we're bringing into the space early in design or construction. Pollutant release will vary depending on the materials used. Particulate matter, moisture and gas phase pollutant release occurs as materials dry and cure.

Typical pollutant sources include:

  • Paints,
  • Urethanes,
  • Plasticizers (phthalates),
  • Flame retardants,
  • Tile grout,
  • Grout sealer,
  • Plastics, and plastic components,
  • Cleaning products,
  • Sheetrock mud,
  • Insulation binders and other sources of aldehydes.
  • Significant moisture is being emitted from building materials during the post- construction.
    • Home framing alone can hold many hundreds of pounds of moisture beyond long-term dry conditions.

Owner decisions on furnishings, fragrances and cleaning products also introduce pollutants and degrade IAQ.

Use your nose, it knows.

Or more simply, if you can smell it, it's probably there. In general, estimate 1-2 months for this phase, with rapidly decreasing emissions of most major pollutants. Semi- volatile VOCs (phthalates, bromated flame retardants, etc) can take years. Always air out the home prior to occupancy after it's been closed for more than a few days.

General Strategy 

Let the pollutants out. First out of the materials, this means that heat, humidity and UV are desirable during this phase. Second, once released from materials, let the pollutants out of the home. Avoid storing carpets, towels and upholstered furniture in the home during this phase as pollutants can adsorb into those materials. As much as possible, place upholstered furnishings, carpets, draperies and towels in the direct sun for several hours prior to bringing into the home.

Use your point source pollutant control fans in the baths and kitchens (using the range hood is always a good idea). Be sensitive to humidity conditions in the home - though humidity promoted outgassing (hydrolysis), it is considered an interior pollutant because it can lead to mold and other moisture related issues and can impair dimensional stability in trim work and furnishings

Specific Strategy 

Depends on season and outdoor conditions. Given that we are currently in a cool dry fall weather pattern, leave open to exterior air as much as possible. Close the house periodically to heat it up (82-84F), then vent.

Actions during this Phase

  1. Open house as much as feasible
  2. Close to heat up occasionally
  3. Leave dehumidifier set to 60%
  4. Leave dehumidifier ventilation set to ON
  5. Check and change filters frequently
  6. Create post-construction filters by connecting a 24"x24" MERV11 or MERV 13 4" pleated media to the Return side of a simple box fan.
  7. Use point-source pollutant control ventilation fans
  8. Check the HVAC filters before move-in! 

Phase 2: Long Term Occupancy 

The basic assumption during this phase is that materials and surface finishes will have outgassed and the dominant pollutant sources are now external to the conditioned volume of the home in the form of pollen, dust, combustion by-products and other outdoor IAQ pollutants.

indoor air quality

Other pollutant sources during this phase are materials/furninshings that are brought into or created within (cooking, showering) the conditioned volume of the home through occupant actions. Cooking is a big deal. Don't discount it! 


Actions during this Phase

  1. Maintain the space relative humidity at 55-60%
  2. Maintain space temps for thermal comfort as desired
  3. Ventilation ON when occupied
  4. Note that there is no need to maintain an occupied cooling set point when the home is unoccupied. Reasonable to set the controller to 84F - assuming no art, antiques or musical instruments "say" otherwise
  5. Check and change filters frequently until pattern/schedule is identified, typically twice annually for 4" and 4 times/year for 1-2" pleated media filters
  6. Use point-source pollutant control ventilation fans diligently
  7. Be mindful about what you bring into the home and what IAQ pollutants you create/release within the home 

Final Thoughts

This is not an exhaustive list and we probably missed something. But in general, this is a strategy that can really make a difference for a new home's IAQ. 

Another astounding fact to ponder:

Because Americans spend approximately 22 hours every day indoors, susceptible individuals are at much greater risk of adverse health effects from chronic low levels of exposure to indoor air pollutants over time. Along with particulate matter, gases such as ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide; microbial and chemical volatile organic compounds; passive smoke; and outdoor ambient air are the most common types of air pollutants encountered indoors.
— The Journal of Allergy and Clinical Immunology, Volume 121, Issue 3, March 2008, Pages 585–591

If you thought the green building movement was big, wait until you see what's coming down the road with regard to Healthy Homes. Big manufacturers are positioning to brand around this idea. Google's own search data points to a shift in what people are searching for when researching their own homes. Hint: they're not asking about energy use as much as they are healthier housing options. 

Also, don't forget you can absolutely keep tabs on your own home's IAQ with consumer facing devices now. You don't need a vast array of specialized sensors with complex interfaces to know when your air is bad. Go down to TreeHouse and pick up a FooBot. We have one in the office and the CO2 monitor alone is a great way for us to know when a long-winded meeting should end. :) 

foobot indoor air quality

Until next time, building science enthusiasts. 

Energy Vanguard - The Contractor's Fear of Third-Party HVAC Design by Positive Energy

Greetings building science enthusiasts,

We've been reading Dr. Allison Bailes' newest blog post over at Energy Vanguard and it's too juicy not to share. You'll get the gist pretty quickly - why are installing contractors (generally) so fearful of an engineer's design?

Answer - well, it's complicated. 

What if a builder refused to build from plans drawn by an architect? What if a tile installer refused to implement designs handed to them and instead did their own thing? What if an HVAC contractor told a potential client they wouldn’t install a system designed by a third party to ACCA protocols? One of those questions is more real than the others. Of course builders build from architects’ plans and tile installers don’t throw out designs they’re asked to implement. But third-party HVAC design is a different animal.
— Dr. Allison Bailes III, PhD

There is some nuance to the situation he's bringing up. Installers may experience resistance due to the lack of quality third party design in their market or they may have had a poor experience previously with a third party designer. What this speaks to, at least from our perspective, is the need to integrate. From the architect to the GC and installer, the mechanical designer needs to have a mastery at navigating communications and facilitating productive conversations across the project team. 

Here at Positive Energy, that's our primary directive when we engage with firms to pull off successful Integrated Mechanical Designs. If we can't maintain fluid communication and establish clear goals across the team, our chances of experiencing a negative outcome go up. But it's solvable! And we work hard to make sure it's happening.

More thoughts from Allison: 

Where I’d like to see us get to is to have a relationship between third-party HVAC designers and HVAC contractors like that between architects and builders. Architects and builders are both licensed professionals, so one part of the answer may be to require licensing for third-party designers. I’m not convinced that would solve the problems, though. If licensing were the answer, the contractors — who have to be licensed in most places — would already be doing everything properly. And my friend Kristof Irwin of Positive Energy in Austin, Texas is a licensed engineer who faces the same kinds of problems.
— Dr. Allison Bailes III, PhD

Thanks for the shoutout, Allison! 

He's absolutely right. Licensing regulations exist for a reason and we take that very seriously. We've got a robust team here with many credentials, but the fundamental code of ethics by which we operate have to do with the professional engineering license. We are obligated to look out for the health and safety of the public and our clients. That's why our designs are so robust and detail oriented.

And we totally understand that robustness can be intimidating to an installer we've never worked with before. But we also understand that if the design isn't implemented correctly, all our hard work was just wishful thinking. And that encapsulates why we offer support to the GC and installer in the CA phase of our projects. As long as we're in fluid communication, the kinks work out pretty easily and we're definitely in the business of setting this precedent across the industry. We think we can all do a lot better and the world will benefit greatly for it. 

Moral of the story: Allison, once again, presents us with another set of great ideas. If you're not already following his blog, don't miss out. He's got a lot to say and he says it well. 


Architecture In Review: Witt Architecture Office by Positive Energy

Greetings building science enthusiasts! 

witt architecture office logo

Hope your respective summers have been great and now that the autumn season is getting underway, we hope you are taking the time to enjoy the built world around you. A lot of energy, time, and exertion went into designing and creating the homes and buildings we spend almost all our time in each day. The design details make a huge difference in quality for a home or building and it takes an architect with the right kind of wisdom, skill, and experience. That's exactly what our friend Scott Witt brings to the table. 

Scott is a registered Architect in the State of Texas and Certified Passive House Consultant (CPHC) and when he's not designing excellent houses, sometimes he helps us design construction details for our clients. He's also been a guest on The Building Science Podcast. He's an all around great guy to know and have on your side when it comes to thoughtful and intelligent home design. His work is truly where building science and architecture collide. 

Check out his work for yourself. Give him a ring and ask him what differentiates his process. You won't be disappointed. 


AIA Houston Presentation by Positive Energy

We wanted to make available the slides Kristof presented on VRF equipment for the AIA Houston, Wednesday July 12. We also included the audio that was recorded to accompany the slide deck.You'll find both the audio and the PPT file access below. Please enjoy! 




What's The Deal With Air Conditioning? by Positive Energy

Greetings building science enthusiasts, 

Miguel here with a brief mid-summer musing. It's hot out so I figured we could talk about air conditioners for just a moment. Nothing too deep, just a simple few thoughts to stir that summer mind-stew for you. 

Air Conditioning The New York Times

The New York Times just published an piece on climate change and the role that ever growing demand for global air conditioning plays in the carbon puzzle that we, as a society, find ourselves trying to work out. It's called "If You Fix This, You Fix a Big Piece of the Climate Puzzle" and it's a quick read if you've got a little time. For those of you who want a digested version, we've provided the big points below. 

Fixing air-conditioning is, let’s face it, not the most exciting solution to climate change.

Perhaps for the same reason that remodeling a kitchen is more enticing than replacing a water heater, devising greener refrigerant chemicals will never make headlines like solar installations or electric cars do. You just can’t take a great selfie with the inside of an air-conditioner.
— Lisa Friedman, The New York Times

This is a decent way to frame the importance of HVAC, but there's obviously so much more to be said. The salient point for me is that HVAC kind of falls flat in people's ears because it's not as exciting as the other sophisticated technology in our lives. Nobody stands in line for the new designer series of an air conditioner like they do for the newest iPhone. 

I can't count how many times my friends' eyes have glazed over when someone we meet in a social outing asks me what I do. I have to unpack quite a lot to explain the relevance of HVAC to the global economy and how architectural and construction processes work.

There are a whole lot of people in the world who don't care about air conditioners beyond whether they work and keep them cool and I don't blame them. It's not exactly Game Of Thrones material (by the way, if you're a fan and didn't know, the new season premiere is this Sunday. Get with it, already). But it's precisely because people find it a little boring that I am so excited that The Times published a front page piece on HVAC's role in curbing climate change. 

These little boxes matter a whole lot.

New research from the Lawrence Berkeley National Laboratory in California indicates that adding improved efficiency in refrigeration and phasing out fluorinated gases used for cooling, as mandated by international agreement, could eliminate a full degree Celsius of warming by 2100. Given that the “business as usual” trajectory leads to 4 to 5 degrees Celsius of warming, that is shaving off a pretty big slice.
— Lisa Friedman, The New York Times

Lawrence Berkeley National Labs just keeps bringing in the heavy hitting data points for us. This is a big deal and should be a huge reason more people would care about HVAC. If you don't talk to your kids about thermal comfort and energy flows, who will? 

That’s because from India to the Philippines to South Africa, air-conditioners are increasingly a must-have item. Less than 10 percent of homes in India have units, but air-conditioning makes up 40 percent to 60 percent of the country’s electricity demand in major cities like New Delhi. Businesses and homeowners in Asia and Africa are expected to buy an estimated 700 million air-conditioners by 2030, and 1.6 billion by midcentury. Without major changes in the way we cool ourselves, those units will in turn crank up the global furnace.
— Lisa Friedman, The New York Times

Bottom line - air conditioning is no longer subject to an American-specific product demand. Much of the developing world is seeing massive HVAC adoption, not always with the most forethought to how to do things well. 

Efficiency doesn’t require a global treaty. It does, however, call for new regulatory policies on manufacturing standards and labeling.

It matters, researchers say, because cooling has a direct relationship with the building of coal-fired power plants to meet peak demand. If more air-conditioners are humming in more homes and offices, then more capacity will be required to meet the demand. So 1.6 billion new air-conditioners by 2050 means thousands of new power plants will have to come on line to support them.

The Lawrence Berkeley study argues that even a 30 percent improvement in efficiency could avoid the peak load equivalent of about 1,500 power plants by 2030.
— Lisa Friedman, The New York Times

This is good stuff. Efficiency needs to be a part of the conversation, but we also need to talk about how we deliver that system in the systems of architecture and construction. Don't let your  guard down just because something is "efficient." Demand more of your project delivery. 

The countries driving the bulk of demand for air-conditioning — China, Brazil, India, and Indonesia — have energy efficiency improvement policies like labels and incentive programs. But improvements to China’s policies could have sweeping gains, because it is the key exporter to countries primarily in Southeast Asia, where demand is growing. India’s Ministry of Power is working to develop a program for bulk purchases of superefficient air-conditioners, which may include refrigerant alternatives to HFCs.
— Lisa Friedman, The New York Times

Policy matters. A lot. Be civically engaged and let your representatives know how we can lead the world in energy policy, especially when it comes to air conditioning. And most importantly, don't forget that these air conditioners are meant to provide comfort and clean air to people. It's crucial to continue the discussion on indoor air quality and thermal comfort rather than just diving down the rabbit hole of energy efficiency. They're not mutually exclusive ideas and, when thought about properly, actually can improve in tandem. 

Want to know more about the VRF systems that are so popular around the world? Check out our podcast episode about that very topic.

How To Kill A Good Business by Positive Energy

Here's some food for thought. Of course they're broad stroke statements, but useful to consider. 

Product Weakness + Lack Of Innovation = Dead Business Models

  • Netflix did not kill Blockbuster. Late fees and a lack of innovation did. 
  • Uber did not kill the taxi business. Limited taxi access, fare control, and a lack of innovation did. 
  • Apple did not kill the music industry. Being forced to buy full-length albums and a lack of innovation did. 
  • Airbnb did not kill the hotel industry. Limited availability, limited pricing options, and a lack of innovation did. 
  • Amazon did not kill other retailers. Bad customer service and experience alongside a lack of variation and innovation did. 

Technology by itself is not the real disruptor. Being non-customer centric and neglecting to innovate your products and services are the biggest threats to any business. 

How are you staying alive?