When people say, “Earth’s climate has always changed,” I think back to a college geology class I took in 1992. The professor’s PhD research specialty was drilling deep in glaciers, peering back hundreds of thousands of years, and comparing carbon dioxide (CO2) levels with surface temperatures. My professor would agree that both temperature and carbon-dioxide levels have always varied. But he would add that they have always correlated very closely with each other. The relationship is complicated, with higher temperatures often preceding higher CO2 levels, but they always end up following a similar path, largely because of what we now know as the greenhouse effect—the CO2 and other gasses trap some of the sun’s energy from leaving the atmosphere. The problem is that CO2 levels are now much higher than ever before, and the temperature is just beginning to catch up. (CO2 is not the only greenhouse gas, but it’s by far the most common, so it is used as currency: other greenhouse gasses are typically converted to the damage they would do if they were CO2.)
Even with supercomputers, scientists can’t predict exactly what the results of climate change will be, any more accurately than they can accurately predict the weather for next week—there are just too many variables to consider.
But just as we know within a certain range what the weather next week will likely be, scientists have an increasingly accurate picture of what the future holds for us, and it’s not good.
In October 2018, the United Nations released a report from their International Panel on Climate Change, summarized with, “Large, immediate and unprecedented global efforts to mitigate greenhouse gasses are required.” Previously, the Paris Agreement had bound 200 nations to keep temperature rise to 2°C, but the IPCC report cites 1.5°C (2.7°F) as the maximum we can reach without catastrophic results. While a couple of degrees may not sound like much, it will have enormous impacts on the world as we know it: stronger storms, acidifying oceans (and the associated loss of shellfish and coral reefs), a weakening gulf stream in the Atlantic that would cause much colder and more extreme weather in Europe, and the decline of species and ecosystems. Increasing drought and higher temperatures will cause migrations that will spark hostility. Some sources seek to inject uncertainty into the UN’s predictions, but the vast majority of the world’s scientists agree and are already measuring the changes as they occur, though they are often all but impossible to observe directly. A 1°F temperature rise isn’t exactly obvious.
Believe it or not, buildings do matter
This is the biggest challenge humans have ever faced, and it requires the world to act together for this common cause. Every action, large and small, has consequences, and this is an unprecedented opportunity to work together. We need to drastically reduce carbon emissions, and we need to prepare for the possibility that we won’t be able to prevent climate change from accelerating.
Buildings have a big impact on greenhouse gas emissions, in two ways: (1) their operating energy, the total impact of the energy needed to heat, cool, and ventilate a home or other building, and to power its lights, outlets, and appliances; and (2) their embodied energy, which includes everything needed to create and install a material or product and, some argue, to recycle it as well.
In the United States, both operating energy and embodied energy are heavily dependent on fossil fuels. Globally, almost 40% of energy used is related to building construction and operation. The only country that contributes more greenhouse gas emissions than the United States is China, which has twice our emissions but four times our population. According to the Department of Energy, U.S. buildings account for 39% of primary energy consumption and 72% of all electricity consumed domestically, and together they contribute more to total greenhouse gas emissions than either the transportation or the industrial sectors. Including embodied energy, the United Nations calculates the impact of U.S. buildings to global warming emissions at 48% of our total emissions.
What we can we do about it: Small steps
The ways to reduce energy consumption are well known: improve airtightness and insulation levels; install efficient windows, doors, fixtures, and equipment; design to take advantage of the sun’s rays (while guarding against overheating); be smart about how you operate your home.
Energy improvements with a return on investment of 5% or higher are a safe place to put any extra money, and even lower returns can represent an affordable donation toward environmental stewardship, with better returns than bank savings accounts.
Some simple ways to reduce operating carbon are to use LED bulbs (with the variety now available there is no excuse for people still clinging to incandescents or halogens). Air-seal your home; as much as 50% of energy lost is through air leaks. Add insulation. Install more efficient equipment. Be ok with being a little warm in summer and a little cool in winter; previous generations were not the wimps that we have become. More-efficient envelopes can be more susceptible to mistakes, so learn the building science needed to make them safe or hire people who already understand how to do it. It’s not hard, but it is different than building in 1950. Net zero energy homes—those that generate as much energy as they use on an annual basis—need to be mainstream, not niche.
To go a little further, like many designers of efficient homes, I use an energy modeling program to weigh building options: everything from overall shape and orientation to window and equipment selection to wall and foundation systems. I use BeOpt, an energy modeling program that is simple to use and a free download from the Department of Energy, and show clients the return on investment to go above code-minimum construction. BeOpt’s most unique feature is that it can automatically show the most financially-prudent path to specific energy use targets, all the way to net zero or net positive annual energy use, using nationwide average costs. The user can modify costs or add new assemblies to the substantial list programmed in. I tell clients that considering the stock market is due for a slowdown, energy improvements with a return on investment of 5% or higher are a safe place to put any extra money, and even lower returns can represent an affordable donation toward environmental stewardship, with better returns than a bank savings accounts or similar low-risk vehicles.
Finding the balance point between expenditures and gains is also the intent behind the Pretty Good House approach to home design and construction, which you can read more about at Prettygoodhouse.org.
Traditionally, operating energy has been considered much more important than embodied energy, as the overall emissions from operation for a typical building are around 80% over 50 years compared to 20% for embodied energy. But with the climate clock ticking, it is critical to reduce embodied energy as well. (Read The New Carbon Architecture by Bruce King for a thorough analysis.)
The simplest way to reduce the impact of the materials used is to use less of them: design and build smaller homes, renovate instead of building new, recycle or upcycle whenever possible (and use materials that can be reused in the future), shift to multi-family buildings instead of single-family homes. Another is to avoid materials that contribute more heavily than others; two common construction materials strongly tied to global warming are certain types of foam and concrete.
The most readily available and affordable rigid foam, extruded polystyrene (XPS) uses blowing agents that are 1400 times more damaging than CO2. There are two viable alternatives: polyisocyanurate and expanded polystyrene (EPS). I have been designing high-performance homes on tight budgets for over five years, without specifying XPS, so it is possible—it just requires a little more legwork to get the right materials. (Note that I said I had not specified XPS; it still shows up occasionally because it’s so versatile and easy to get that builders sometimes use it instead of what I spec.) Conventional closed cell spray foam has blowing agents that are almost as bad as those in XPS.
Many cast concrete footings are oversize, built to standard sizes instead of optimized for their particular sites and structures. Foundation walls are often thicker than they would need to be if they had proper steel reinforcing and were allowed to cure slowly.
Concrete is the most commonly used construction material in the world and the Portland cement in it is responsible for more than 8% of total CO2 emissions. It’s not going away, but it is possible to reduce its impact. The easiest is to simply use less of it. Many cast concrete footings are oversize, built to standard sizes instead of optimized for the site and structure; foundation walls are often thicker than would need to be if they had proper steel reinforcing and were allowed to cure slowly. Where basements are common they are rarely necessary, and they require more concrete and insulation (almost always climate-damaging foam) than a slab foundation. It’s even possible to minimize the amount of foam used in a slab-on-grade foundation; I recently designed a small house with a concrete-free slab; we simply ran an insulated grade beam around the house, and inside that we floated a wood floor over high-density EPS foam. I’ve also been specifying concrete with pozzolan admix, which uses industrial wastes (typically fly ash) to replace part of the Portland cement while maintaining or improving the strength. Another, new technology injects CO2 captured from factory emissions into concrete, resulting in a stronger concrete and capturing the greenhouse gas. CarbonCure, one producer in this category, is already available at limited plants around North America.
Building-science discussion groups are popping up; if you don’t know of one, start one.
Buildings that use less energy and have less embodied energy require a deeper understanding of construction than we needed in 1950 or 1970, so we should expect that more education is necessary to design and build good homes than in the past. There are many educational sources, but one I recommend is to find or start a discussion group. For the last ten years a building science discussion group has met monthly in Portland, Maine, led by builder Dan Kolbert and hosted by Performance Building Supply, and was the source of the Pretty Good House concept. Last spring I started a similar one near me (search “Building Science + Beer” for more info.) Similar groups are popping up elsewhere; if you don’t know of one, start one. Just getting professionals and interested parties together in one room for an informal, open discussion leads to a surprising amount of learning and relationship-building. There are also more formal groups: NESEA, Architecture 2030, Passivhaus/Passive House, USGBC to name a few that I have found valuable.
What we really need to do: Giant leaps
Ideas such as those above are a start and should be the minimum level of thought put into any new home. Unfortunately, the situation is dire, and much stronger action is needed, including:
We need policy changes to force the free market to respond. There are some things that industry and individuals are just not inclined to do without pressure, even when the result will be strongly positive for everyone. The free market can be a wonderful thing, but it’s not good at everything, and has not proved effective against climate change; we are at the point where we need government intervention to encourage behavior in the right direction—and not just our government, as the US does not exist in a vacuum. Very little in the market is not controlled in some way, and fossil fuel production is heavily subsidized in various ways; instead it needs to be taxed, with the earnings going toward policies and technology to help us through this next age of climate change. A carbon tax is the simplest and often-recommended policy change, in use and effective elsewhere.
An efficient home may use $300 per month less in energy costs than a poorly built home, money that could go toward a mortgage.
We need to greatly reduce operating energy in all our buildings, through efficiency measures and through cleaner forms of generation. The Passivhaus program was designed in the 1990s to limit each person’s building-related emissions from contributing to climate change. It’s very hard to meet the standard with single-family homes or in more extreme climates, and relatively simple with multi-family dwellings—a hint at which is better for the planet. Going further, the Living Building Challenge charges participants with creating buildings that use fewer resources of all types than they take to build and operate. It’s a challenge indeed, but also quietly setting a new direction in the high-performance world.
The LEED standard has been effective for institutional buildings but the initiative has run out in the residential sector. Building to Energy Star standards is popular where it is subsidized, but the standards are not particularly stringent, and many states don’t provide incentives. Architecture 2030 aims for all new buildings to be carbon-neutral by 2030, 20 years ahead of the timeline set in the Paris Agreement, but in alignment with the recent UN report.
New buildings need to be carbon neutral to meet the necessary targets, but the existing building stock contributes much more to operating energy use; we need mass weatherizing and equipment upgrades.
Banks need to consider operating costs when providing loans. An efficient home that uses $300 per month less in energy costs than a poorly-built home could pay for a $60,000 larger mortgage to fund the energy improvements and solar power generation. A few banks are already doing this but it’s rare.
For power generation, arguments against subsidized photovoltaics are valid, as they favor those wealthy enough to afford a PV system. But those are typically the same socio-economic class of people who also profit from owning stocks in subsidized fossil fuel companies, so the argument does not hold up to scrutiny. The more PV that gets installed, the more affordable they become, and the more they contribute to a stable, distributed energy generation system. But those smaller systems are not being built quickly enough; what we really need is much more industrial-scale renewable power generation. As an aesthetically-oriented environmentalist I hate to see the changes these power generators bring to the viewscape but compared to the alternatives I don’t think we have a choice. At least creative farmers can graze animals among PV fields and wind turbines. (The UN report also had a harsh critique of industrial animal-raising practices, but some encouragement for small, diversified farms including multi-species rotational grazing, which dovetails with using fields for PV generation.)
We need more housing to accommodate a population that, for better or worse, will continue to grow. But we can’t all live in 3,000 sq. ft. custom homes in the countryside. At bare minimum, we need to build smaller, more efficient homes, but we really need to be building multi-families buildings, which are a much more efficient use of resources. New buildings need to be carbon-neutral to meet the necessary targets, but existing building stock contributes much more to operating energy use; we need mass weatherizing and equipment upgrades.
As for materials, one technology that is nascent in the US but has proved itself elsewhere and is gaining traction in the US is Cross Laminated Timber (CLT). It will probably never pencil out for single-family homes, but it has long been used in Europe for larger buildings, where it can replace a significant amount of the carbon-intensive concrete and steel normally used in such buildings. If it comes from a sustainable source it can be a strongly carbon-negative material, meaning the more we use, the more we save, for buildings where steel, concrete, and foam or mineral wool insulation would normally be used.
Some approaches are on the fringes, but as consumers become educated about alternative ways to build, they are becoming more popular: straw bale construction, high-performance offsite construction, tiny homes (on or off wheels). All have tradeoffs compared to conventionally sized and built homes, but each has advantages.
Use local materials. While moving large quantities of products from one side of the globe to the other can take a surprisingly low amount of energy on a per-unit basis, the heavier the product the better it is to buy local, especially if buying local supports your local economy. In Maine, the most heavily forested state in the country (on a percentage basis), the most affordable wood siding comes from the west coast. We are just now getting our first CLT plant, and research is under way on wood-fiber insulation, long common in Europe.
What if we don’t do enough?
We are at the most critical juncture in human history. Your future self, your children, and your grandchildren will know that you had the opportunity to do something now and either chose to or chose not to. Every decision matters.
The United Nations’ recent report has set a dire prediction. We will find ways to do better, but we all must prepare for a more severe climate (including stronger and colder winters) and what that will do to various societies. The damage we are inflicting today won’t be fully felt for decades, so it’s hard to focus attention on something that feels intangible. But we don’t have a choice. I recently described the situation to someone who was trying to convince me to focus on serving the needs of those who suffer from Lyme disease, currently at least 200,000 Americans. A noble cause, and their needs are real, but compare 200,000 individuals with every single person and other animal on the planet. Just in the next hundred years that’s at least 20,000,000,000 people who will be affected, many severely. That’s 100,000 times more people than currently afflicted with Lyme disease in the US, and more than 50 times our current population. Our failure to act will mean all of them will suffer, and many species will be eradicated, because we couldn’t act in time. And that’s just in the next 100 years. Consider the common question, “if you could go back in time and change one thing, what would you change?” We are at the most critical juncture in human history. Future-you, your children and grandchildren will know that you had the opportunity to do something now and either chose to or chose not to. Every decision matters.
With the significant changes that will likely happen, despite our efforts, we need buildings that are more resilient in the face of stronger storms, longer droughts, and potentially questionable power supply. We need to show developing countries how to build resilient communities that are interdependent and secure. (And we could learn a lot from the low-impact lifestyle often practiced, out of necessity, in developing countries.)
What if we don’t need to do anything?
There is the slimmest of chances that climate change deniers are right; after all, this is science that is impossible to prove with 100% accuracy, and the climate and its interaction with all of the earths’ systems is a big, dynamic thing. What if all of the societies on the planet work together toward a common goal, instead of warring over resources? What if people had cleaner air, lived in healthier homes, lived healthier lifestyles and had more close relationships, in more comfortable homes? What if we support local economies instead of sending our money overseas and complaining that locals don’t have work? What if we are better prepared for droughts, storms and power outages? What if we better understood the connection between ourselves and our planet’s ecosystems? Wouldn’t those all be good outcomes?
20 billion people and incalculable species are depending on you to do the right thing.