Common Myths About Green BuildingFebruary 2022
by Paul Eldrenkamp
We posted a version of this post in 2015. Since then, we’ve learned a lot more about the impact of our building practices and the speed with which the climate is changing. It’s even more important now that we acknowledge and move beyond entrenched myths about what truly sustainable construction is and isn’t. It’s also important that we call out newer myths that are hampering efforts to decarbonize the building sector—efforts that we must accelerate in order to achieve our climate emissions reduction goals.
Myth #1: You can succeed at being "green" without bothering to measure the impact of your actions.
I'm pretty sure what most people mean by "green" building is to build new or to remodel in a way that's more sustainable than business as usual. In turn, most definitions of "sustainable" would probably include the need to use less than before— less energy, less water, and so on, or to emit less than before—less carbon dioxide, methane, and volatile organic compounds (VOCs). The only way to know if you're using less or emitting less, though, is to measure how much you're using or emitting over time, and to note whether the trend line is heading in the right direction. Sadly, that rarely happens in the world of green building or remodeling. Most people have no idea how much energy they use in any given year in their home, or whether it was more or less than the previous year. There's almost no scorekeeping going on, in other words. If you don't keep score, how can you possibly know if you're winning?
Myth #2: "Green" is all about product choices.
Unfortunately, truly "green" building is not about all the cool stuff we can buy and put into our homes. It's mostly about the stuff we don't buy and put into our homes. Occasionally a community will have a local green homes tour, and we all get a chance to march from green house to green house and admire bamboo flooring, recycled glass tile, and roof-mounted PV systems. These are all good and noble things, but a true green homes tour would be pretty boring, as it would consist of visiting perfectly ordinary homes and admiring the very low utility and water bills of those homeowners who are particularly watchful against consuming too much of anything— and still somehow manage to live happy, fulfilled lives.
Myth #3: Heat pumps aren’t reliable in cold climates.
Heat pumps use electricity to move heat from one place to another. Your refrigerator is a classic heat pump: it uses an electrically-power pump (plus a refrigerant gas in a closed-loop system) to move heat from inside the refrigerator to outside the refrigerator. When used for household space conditioning, heat pumps in cooling mode move heat from inside your house to outside your house; in heating mode, they move heat from outside your house to inside your house. That second part is what often gives people pause: It’s 10° outside—how can there be any heat to move into the (hoped-for) 70° air inside my house? Until 8 to 10 years ago, this was a legitimate concern: heat pumps did not perform well at low outdoor temperatures and relied on expensive electric resistance heat to make up the difference. But current heat pump technologies are much better and can reliably and efficiently deliver heat indoors even with below-zero outdoor temperatures. (This concept becomes more intuitive if you think in terms of the Kelvin scale: 0°F is 255K, 70°F is 294K, and the boiling point of the most common heat pump refrigerant is about 239K. These conversions perhaps communicate better that even at 0°F, outdoor air still contains a lot of usable heat. Also, 0°F is well above the boiling temperature of the refrigerant—the critical temperature in all heat pump technologies.)
Myth #4: A super-tight building can't truly be "green" because it will have poor indoor air quality.
It's certainly true that a super-tight house will have poor indoor air quality if it doesn't also have a well-designed and installed ventilation system. The key to good air quality is good ventilation—a way of assuring that stale air in the house is replaced with fresh air at a steady rate. The fact is, though, that it's much easier to assure good ventilation in a very tight house than in a leaky house. A leaky house will typically be over-ventilated in the winter, leading not only to unduly high heating bills but also to uncomfortably dry indoor air. And in those periods in the spring and the fall when outdoor temperatures are close to indoor temperatures, a house that relies on random air leaks through the structure will often be under-ventilated. Look at it this way: You can implement a well-conceived ventilation strategy to provide fresh air to your house, or you can rely on the builder's mistakes. Which sounds better to you?
Myth #5: A superinsulated building is always greener than a code-level building.
At a Northeast Sustainable Energy Association (NESEA) conference keynote a couple of years ago, the Byggmeister team learned that a super-insulated building can, with the wrong choice of materials, have a significantly larger carbon footprint than a perfectly ordinary code-level building. The keynote presenters, Canadian builder and researcher Chris Magwood and Ace McCarleton and Jacob Racusin of Vermont-based New Frameworks, have done some ground-breaking work on this topic. For several decades, the primary (sometimes exclusive) emphasis of sustainable construction and renovation has been minimizing operating energy. More recently, we’re learning to ask, “How much carbon are we investing in those operating energy reductions, how much carbon are we saving—and over what timeframe?” When considered within that framework, the math doesn’t always look as good as we had assumed. So, in place of a focus on operating energy, we’re learning to think in terms of how much embodied carbon we’re investing in a project and what the payback on that investment is in terms of operating carbon reductions over the critical time period of the next 10-30 years.
Myth #6: "Green" buildings are environmental assets.
This myth gets promulgated in part because there are no awards given for not building something. To achieve LEED-Platinum, Passive House, or Net Zero, for instance, you must build a building. The problem is that even the “greenest” building projects cause environmental harm (one possible exception might be Living Building Challenge certified buildings, but the regenerative requirements of this certification remain out of reach for all but the tiniest fraction of projects). Fundamentally, buildings are efforts to keep nature at bay. Think about it: We want our buildings to be warm when it's cold outside, cool when it's hot outside, light when it's dark outside, and dry when it's wet outside. Of the millions and millions of species in the world, there's only a small select group we're willing to share our buildings with; and, perhaps most telling of all, any sign of the most fundamental renewal force in the natural world— rot and decay—is the surest indication of failure in a building. A building is thus, at root, an attempt to thwart natural processes (and, in that vein, lawns serve as a sort of protective moat to aid that effort). Thus, the best that we can hope for, at least in the near term—and the best that we must continually strive for—is to make our buildings much less bad. That may not sound inspiring initially, but this perspective hasn't deterred us these past forty years. If anything it's spurred us on and, more recently, has kept us laser-focused on decarbonization. Eliminating carbon from the building sector is both essential and achievable. That's more than enough inspiration for us.