The Passive House Network's marketing pitch: It's all about comfort.

“People don’t buy for logical reasons. They buy for emotional reasons.”- Zig Ziglar

I am a serious fan of this new marketing campaign from the Passive House Network, the American nonprofit “focused on the rapid implementation of Passive House building standards to robustly address our climate and social justice crises.” Most people think of the Passive House standard in terms of energy consumption, but many have tried to pitch its other attributes. Kim Ravold of PHN tells me:

“At first glance, the Passive House Standard appears to be driven by efficiency, because the end result dramatically lowers energy usage. What’s less apparent is that these energy efficient benchmarks are linked to occupancy comfort. Each drives the other, not just in terms of surface temperature, but also cleaner air, reduced noise, and fewer pests.”

These are issues we have been discussing for years, but the message was often lost. Back in June, 2014, architect Elrond Burrell wrote:

“Energy efficiency is actually only part of passivhaus. People don’t often realise that the Passivhaus Standard is also a rigorous comfort standard that ensures a building is free from draughts, free from cold spots, free from excessive over heating and provided with a constant supply of fresh clean air. And it does so with the minimum amount of energy.”

Note how Elrond mentions overheating. Many people believe that Passive House has a cold weather bias (it did start in temperate Germany) but it keeps heat out as effectively as it keeps it in. But to really understand why this works and why it is so important, we first have to explain what comfort is and how our bodies work.

You might ask what safety and security has to do with comfort, but that is in fact where it comes from in the first place. The root of the word Comfort is in the late Latin "conforto" (to strengthen greatly) from earlier Latin, con- (“together”) and fortis (“strong”). So in a sense, redefining comfort as safety and security is going back to its roots. Suzanne Shelton, in her 2022 report "What is home? wrote:

“Safety and security aren’t just important – they’re the primary way we define comfort. In other words, we can’t feel comfortable in a home if we don’t feel safe and secure in it.”

“I don’t know whether to open the windows, blast the heat, or just give up entirely.” Many people just give up, because they don’t actually understand how comfort works. I have written that “architects don’t get it, mechanical designers don’t get it (they will just sell you more equipment), and the clients don’t get it.” I am not even sure most Passive House people get it. I try to explain comfort in my next book, The New Manual of the Dwelling; here is an excerpt.

Comfort is a state of mind

Engineer Robert Bean explains that our bodies have 165,000 thermal sensors spread out over 16 square feet of skin, about the area of the hood of a car. These sensors send signals to the brain, which determines whether the body is losing heat, in which case we feel cold, or gaining it, in which case we feel hot. We can gain or lose heat through conduction (direct touching), convection (air carrying the heat away), or evaporation (sweating) but fully 60% of heat loss is through radiation—the transmission of infrared rays that go from warmer surfaces to cooler ones. Lisa Heschong has a great explanation in her wonderful little book, "Thermal Delight in Architecture,"

"There is a basic difference between our thermal sense and our other senses. When our thermal sensors tell us that an object is cold, that object is already making us colder. If, on the other hand, I look at a red object it won't make me grow redder, nor with touching a bumpy object make me bumpy. Thermal information is never neutral; it always reflects what is happening directly to the body. This is because the thermal nerve endings are heat-flow sensors, not temperature sensors. They can't tell directly what the temperature of something is; rather, they monitor how quickly our bodies are losing or gaining heat."

Physicist Allison Bailes explained it less artfully and more hilariously in his notorious post Naked people need building science with an image of a naked man jumping on a bed in front of a big cold window in a warm room.

"Every object radiates heat. The amount of radiant heat it gives off depends on its temperature (to the 4th power!), surface area, and emissivity. So our naked man jumping on the bed in front of the single pane window is giving off not only more views than he’s getting back but also more heat. The surface of the window is much colder and gives off far less heat, so the net flow of radiant heat is away from the man in his birthday suit. He’s cold!"

Your skin and brain do not care what temperature the thermostat is set at; what matters is the rate at which they are gaining or losing heat to surrounding surfaces.  Your skin and your brain care about the Mean Radiant Temperature, the “theoretical uniform surface temperature of an enclosure in which an occupant would exchange the same amount of radiant heat as in the actual non-uniform enclosure.”

This is why Passivhaus houses are so comfortable- the temperature of the walls and windows are so close to our skin temperature. If the walls are warm, you are warm, and in hot weather, the reverse is true- if the walls are not hot, then neither are you. As engineer Es Tresidder confirms:

“We also lose heat through radiation, regardless of the air temperature, to the solid surfaces surrounding us. This radiative heat loss depends on the temperature of those surfaces and how close we are to them. The warmer they are the less heat we lose in this way; the colder they are the more heat we lose.”

As we noted earlier, “Safety and security aren’t just important – they’re the primary way we define comfort.” Wildfire smoke is a huge health and safety issue that people have not come to grips with- the dangers of inhaling PM2.5 and other products of combustion. I wrote about this earlier this year in Wildfires are another reason that every house should be Passivhaus:

The best way to keep particulates out of our homes is to seal them tightly against air infiltration, and have controlled, filtered ventilation, as you get with the Passivhaus or Passive House system. Chie Kawahara described how her Passivhaus handled fires in California in 2018:

"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.

And my last post was Ultrafine particles are killing us, and most of us have never even heard of them. This is why the airtightness of Passivhaus is so critical- a leaky house admits a lot of pollution and makes air quality impossible to control.

Leaky walls also are cold walls. Energy pioneer Harold Orr used to say that “about 30 to 40 % of your total heat loss is due to air leakage.” They mean uncomfortable draughts, or drafts as Americans call them. Elrond Burrell writes:

“It only takes a tiny hole, gap or crack to allow a cold draught to whistle through into a building and cause discomfort. People rarely think about how much discomfort even a small draught can cause since we’re all pretty used to the odd cold draught here and there. The reality is though, to be comfortable when we feel a cold draught, we need the room to be a few degrees warmer to counter the discomfort the draught causes.”

Finally, we have noise. Years ago, Zach Semke’s firm looked at the impact of Passivhaus for noise transmission. He wrote:

“We asked the acoustic engineers at SSA Acoustics to evaluate just how significant the noise reduction in Passive House buildings is. They studied the design of a 12’ by 9’ section of exterior wall from a typical multifamily unit, comparing two versions of the wall: one using conventional construction and double-paned windows, the other employing Passive House thickness, insulation, airtightness, and triple-paned glazing. Thanks mainly to the greater thickness of both wall and windows, the Passive House wall reduced exterior noise penetration by roughly 10 decibels. And that's before making materials selections that could further reduce sound penetration, like insulating with mineral wool, a naturally soundproof product.”

The decibel scale is logarithmic, with every ten dB meaning a doubling of noise and vice versa, so a reduction of ten dB means it is reducing the noise level by 50 percent. That is a serious turning down of the volume. I concluded:

“It's one of the reasons that I have become so fond of the Passive House concept; you come for the energy and carbon but stay for the comfort, security and quiet.”

Kim Ravold writes in an email: “Comfort is physical, emotional, visceral. Comfort feels like a luxury.” But as I have tried to show here, comfort is also science- we know what causes comfort. The right Mean Radiant Temperature, fresh filtered air, airtightness, silence, all things promised by Passivhaus.

But Kim Ravold also gets that there is the bigger picture, and that there is another kind of state of mind, writing in her email:

“At the same time, when we ask “are you comfortable,” we’re asking the question existentially. Are you comfortable that the buildings we typically design, build, and occupy produce 40% of global carbon emissions? Are you comfortable with a building that contributes to our climate crisis, or do you want to be a part of the solution? It’s not a question of sacrificing comfort for efficiency. Passive House is the building standard we can rest easy with, literally and figuratively.” 

I think it’s a brilliant campaign. Perhaps the greatest salesman ever, Zig Ziglar, wrote “People don’t buy for logical reasons. They buy for emotional reasons.” Energy efficiency is logical, and a hard sell. When I wrote my post How Do You Sell the Idea of Passive House? I concluded: “Really, with health, quiet, security, air quality, luxury and comfort, there is so much to sell about Passivhaus. They should by flying off the shelves if we get the message out.” Kim and the Passive House Network are doing some of the best messaging I have seen in years.