The Zero Emissions Building Exchange in Vancouver, British Columbia is “a centre designed to rapidly accelerate the knowledge, capacity and passion for zero-emission buildings.” I was recently invited to participate in a seminar titled “Marketing the High-Performance Home.” This post is a summary of that presentation, and some of it has been seen previously on Treehugger.
Historically, “High-Performance” meant energy-efficient, and “lower energy bills” is the first benefit mentioned in BC Housing’s Consumer Guide to High Performance Homes, along with “reduced pollution and CO2 emissions.”
But looking at the guide, I couldn’t help wonder why the house shown on the cover was a stock photo of a “luxury home exterior with green grass and driveway at sunset” with a three-car garage, all covered in inefficient double-hung bay windows. It certainly didn’t look high-performance to me. This got me thinking about what a high-performance house actually looks like, and what features of a high-performance house really matter to people these days.
Many people would probably agree with Elon Musk that a high-performance home looks like the photo above, with a roof covered in solar shingles, a big battery pack on the wall, and two Tesla cars in the garage, all on a big suburban lot. But that is a lot of land, and a lot of expensive hardware. This addresses energy consumption and carbon emissions to a degree (it ignores the Embodied Carbon or Upfront Carbon Emissions of building all this stuff). It’s why I have always been a fan of the Passive House principles, where it is all baked into the design of the building, rather than just being stuff that is added on.
The problem is that since it started in the energy crisis of the 1970s, the preoccupation has always been with energy. As the survey above by the Shelton Group found, most people care most about saving money, and with fuel prices where they are, there is never going to be a payback. As for the planet, the last thing they care about is preserving the quality of life for future generations.
But with the climate crisis and the Covid-19 pandemic crisis, we have to look and think about our homes differently. Electrifying everything is important, but it’s not enough, and if we are talking about marketing high-performance, let’s talk about what matters now.
Indoor Air Quality
The fires raging over the Western United States have filled the air with smoke and soot, much of it composed of Particulate Matter smaller than 2.5 Microns, also known as PM2.5.
We used to pretty much ignore PM2.5, mainly because we were all living in a cloud of them when everyone smoked while charring hot dogs over open fires. They were not recognized as a danger or even regulated until recently. There are standards set by the EPA in the United States limiting them to 35 micrograms per cubic meter on a 24-hour average, and when it comes to our homes, there is no enforcement or regulation of it at all. The New England Journal of Medicine recently published a report from the Independent Particulate Matter Review Panel called for a significant lowering of the limits, writing:
“We unequivocally and unanimously concluded that the current PM2.5 standards do not adequately protect public health. An annual standard between 10 μg per cubic meter and 8 μg per cubic meter would protect the general public and at-risk groups. However, even at the lower end of the range, risk is not reduced to zero….On the basis of the scientific evidence, and with the acknowledgment that there is a continuum of adverse effects that decrease as the level of the standard decreases, the panel recommends that the 24-hour standard be set between 30 μg per cubic meter and 25 μg per cubic meter.”
At the time I was preparing this presentation, the PM2.5 Level in Vancouver was 143. That’s dangerously high. However, there are features of the Passive House designs that can make a real difference in how much PM2.5 can get into a home.
The five features of a Passive House were originally developed to reduce energy consumption, starting with a lot of insulation and high-quality windows, but also an extremely airtight building envelope to reduce uncontrolled leakage of air. This significantly reduces the amount of heating or cooling that’s required. But it also means that you need an “adequate ventilation strategy” to exhaust stale air and bring in fresh air. It is a completely separate ventilation system, unlike in most North American homes where the heating and cooling air is recirculated.
But there is a significant side effect that happens when you seal the house and control the ventilation: in a situation like we have now with all the forest fires, there is a significant drop in the levels of PM2.5 inside compared to outside. In a study published in Renew Magazine, it was shown that it drops in half.
When engineers Cameron Munro and Joel Seagren added a HEPA filter to the ventilation system, the levels dropped below the 25 microgram level. (See more on this in Treehugger.)
Chie Kawahara, the owner of the Midori Haus (pictured above) in Santa Cruz, California, described this after an earlier fire:
“We enjoy living in Midori Haus built to the Passive House (Passivhaus) standard. The tightly sealed enclosure, about 10 times tighter than conventionally built houses, keeps random air from coming in from random places. The heat recovery ventilator provides us with continuous filtered fresh air. Only during these extended bad air quality days do we need to pay special attention to our ventilation system to keep our indoor air clean.”
This was not the raison d’être of Passive House, but it is a definite benefit that I suspect will be getting a lot more exposure and generating a lot more interest. And those same features of Passive House that help deal with smoke are likely also useful with another little particle.
Passive House and Covid-19
The SARS-CoV2 virus that causes Covid-19 is incredibly small, at 120 nanometers it a thousandth the size of a PM2.5. But it is carried through the air on droplets of water that we expel when we breathe, talk, cough, or sing. When the Covid-19 crisis started, it was assumed that these droplets fell to the ground pretty quickly and were not a problem beyond about six feet.
In fact, the Federation of European Heating, Ventilation and Air Conditioning Associations concluded (and others came to agree) that “Small particles (<5 microns), generated by coughing and sneezing, may stay airborne for hours according to the REHVA guidance, and can travel long distances.”
Dr. Lisa Morawska and her team studied how SARS-CoV-2 moved around and concluded:
“All possible precautions against airborne transmission in indoor scenarios should be taken. Precautions include increased ventilation rate, using natural ventilation, avoiding air recirculation, avoiding staying in another person’s direct air flow, and minimizing the number of people sharing the same environment.”
Again, fortuitously, the Passive House principles may well reduce the problem of Covid-19 transmission. There is no air recirculation as indoor air is exhausted and fresh air brought in through the Heat Recovery Ventilator. There is not nearly as much air movement because the heating and cooling is not usually done with a big central forced-air system. Kourtnie Rodney, writing for Passive Buildings Canada, calls this “Hygiene Ventilation.”
“Hygiene ventilation focuses on using 100% fresh air to ensure that viruses are not recirculated in enclosed areas, whether commercial buildings or homes. Current research proposes that only 15-20% of air is fresh when using traditional air conditioners, suggesting then that anywhere from 80-85% of potentially contaminated air is being recirculated. Unfortunately, traditional HVAC systems aren’t made to accommodate an intake of 100% fresh air and adapting them to perform such a task would require 4-6x the energy. But Passive House presents itself as the environmentally and economically sustainable option, one that has already been employing hygiene ventilation as one of its basic tenets in the form of balanced ventilation.”
The Walls Help Too
It makes sense that the controlled ventilation could be beneficial in dealing with Covid-19, but surprisingly, even the thick well-insulated walls come into play. That’s because in most homes, the humidity inside has to drop significantly to reduce condensation on windows and possible mold buildup on walls. Doctor (and architect) Stephanie H. Taylor writes in her paper titles, “We need hydrated air to fight infections”:
“Research continues to reveal that dry indoor air is connected to MORE infections in people. This helps explain why the flu season is in the winter, when cold outdoor air – already low in moisture, is brought inside and further dried out when warmed. The obvious solution is to provide indoor humidification to achieve a beneficial relative humidity (RH) level between 40 to 60%. Interestingly, this is already done in animal research laboratories where replacing test subjects that died from seasonal respiratory diseases is costly and could skew the project data.”
In a building designed to Passive House standards, the interior surfaces of the windows and walls are almost room temperature, so there is no reason not to maintain the humidity between 40% and 60%. It’s another case where we came for the energy efficiency, but stayed for the health and comfort.
Beyond the Fringe
In their recent report, The Shelton Group notes that “During times of crisis, fringe ideas migrate rapidly into the mainstream. It’s happening right now as we continue to respond to Covid-19.”
High-performance buildings in general and Passive House in particular used to be considered fringe. They are not anymore. These days, with the climate and health challenges we face, they should be considered standard.
I recorded a version of my presentation, and go on in much greater detail about the “look” of passive house designs, which I have previously discussed on Treehugger here. But the important stuff is distilled down in this post. I also conclude with a summary of the other benefits of Passive House design, including Comfort, Quiet, Security, Luxury, and again, Air Quality. I have covered that in Treehugger before too. And last word to Dr. Wolfgang Feist, co-founder of the Passive House movement, who interjected that we should also remember the main reason for going Passive House: It is part of the solution to the problem of carbon emissions.