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Building Science

Why Does Green Building Matter? – Building Science Podcast

Building construction uses more resources than the auto and aerospace industries combined

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_This podcast series is excerpted from a two-day class called “Building Science Fundamentals” taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation._

For information on attending a live class, go to

In our last show, Dr. Joe Lstiburek discussed a real world example of poor indoor air quality. This week, Dr. John Straube puts our buildings’ energy and resource demands into perspective and contemplates why we’ve let them get to the state they’re in.


This is going to be an issue that’s going to affect how you do your business, and how you live your life for the next little while, so we’re going to talk about the connection between green building, sustainability, building science, and maybe we’ll come to a little bit of an understanding on what we need when we talk about green buildings: what we need, why we would want to go there, and how you’d want to go about doing it in a broad sense.

Buildings are the biggest consumers

So why do we worry about green buildings? Well, the first thing is that buildings consume a lot of resources. And I think most of us know that, but they don’t realize the extent to which buildings use resources. It’s the most consumptive kind of industry on the planet. We use more resources at a larger dollar value than the automotive industry combined with the aerospace industry. We use more energy than pretty much any industry that you can put your finger on. The reason that we don’t notice this as much is that it’s a very disaggregated industry. So some of the largest home builders might have turnovers of a few billion dollars, but there’s only a few of them and there’s tens of thousands of people who are working at the smaller level. And so, unlike the Boeings and the Airbus industries, where there are only a few companies that dominate, in the construction and building industry there are tens and hundreds of thousands of relatively small companies — we don’t realize the impact.

Now they consume a lot of money, consume a lot of resources, consume a lot of energy. And they also pollute, displace, and destroy habitats. I mean it’s pretty obvious when you pave over farmland and put in a strip mall; you’ve displaced some sort of habitat. Now, how much we continue doing that is, of course, arguable, but it is not arguable that they do displace habitat. We also have to recognize that they’re a durable good. So when we complain, say, about the energy content of a pair of running shoes, or a laptop computer, that is a problem that can be fixed very quickly. It doesn’t consume a major part of your household income to buy running shoes. And if the running shoes that you purchase are badly built of environmentally inappropriate materials, within one year you have to get a new pair of running shoes anyway. So you can fix the problem and react to the crisis. When you build a building, you have created a liability for society for the next at least twenty years — maybe one hundred years. Or you’ve provided an asset to society for the next twenty to one hundred years. Depends what you’ve delivered.

Durability plus efficiency equals economy

And this is why there are a lot more codes and standards related to buildings — because they last a long time. A median life for a building might be something like thirty-five years — halfway through its life would be thirty-five years. And that’s why, of course, when we do our energy calculations, we try to figure out what kind of insulation we should put in the wall. We of course use the energy price for thirty-five years from now. That would be the rational approach to saying, “So, if you’re going to make a product that lasts seventy years, we would obviously do our economic calculations based on what the energy would be in thirty-five years.” Right? That’s what a rational economist would do.

Do we do that? Of course not! In fact we haven’t been doing that for the last thirty-five years.

Since the Department of Energy’s energy information agency started reporting data, and making projections about energy, they have never once been right. They have always under-predicted the cost of energy because most of the time they assume energy increases at the rate of inflation. And in the last thirty years it’s more than doubled that. The rate of inflation for energy, depending on whether you’re talking electric, natural gas, or oil, is on the order of 8% per year, compounded. If you use those types of analyses and look at a lifespan of thirty-five to seventy years, you come up with completely different answers than what the code is. The code is, of course, a minimum, right? But in, let’s say in Massachusetts — putting R-40 in an attic doesn’t make economic sense. Economically, knowing what we know today, continuing a straight-line projection of energy prices as they’ve increased over the last thirty-five years, R-40 wouldn’t make economic sense. And yet we put in R-40. In commercial buildings as Joe described with the R-2 window-wall enclosure for a condominium or an office building, [R-2] doesn’t make any sense today. With today’s energy prices [better envelope features have] almost no payback period. Most of the time you can pay that back just by saving on mechanical costs. So the lifespan we look at in buildings is quite different, and that isn’t the only problem if we look at it properly in today’s prices.

So all of these things say that buildings are becoming an increasing focus if you look at the environment beyond our building industry. Recently the auto industry has had this bill passed where they’re going to have to raise their fleet fuel efficiency from the low twenties to thirty-five miles per gallon. And yet, the auto industry is not the biggest producer of CO2, it is not the largest consumer of energy. The building industry is. And eventually someone’s going to have to figure out that the building industry needs to be regulated, and we need to deliver what’s possible, technically and economically.

Now, I’ll show you some numbers that show that people are starting to recognize this; they’re starting to notice that the building industry is the one that’s out of sync with the rest of the world. So that’s why insulation standards are very likely to increase, mechanical equipment standards are likely to increase, and being able to answer to the demands of better buildings is likely to increase.

Exactly how much energy do buildings use?

So I think we’ve all seen the images and the statistics about energy consumption, and resource consumption of buildings: 35-50% of all energy consumed, depending on the country, is used in operation and production of buildings — about 40% in North America. Because it’s such a large industry, we do produce pollution when we’re generating the building materials. When we’re actually making the building itself, we dig big holes in the ground and chop down forests. The good thing about chopping down forests is that people notice it, and it looks ugly. And so there have been campaigns for twenty years to reduce the wanton chopping down of forests, and the wood industry has actually risen to the challenge of providing more wood today than there was ten years ago. There’s more standing wood almost every year in the last fifteen years in America than there was the previous year. The challenge has gone from providing enough wood, to providing enough bio-diversity, rainwater runoff and erosion control, and they’re moving towards that. It’s easier to hide large holes in the ground where people are mining iron ore or cement because they’re kind of localized, you only need a few square miles, and people don’t usually hike through them. But those industries are all starting to respond.

And we can’t ignore — although we’re going to ignore it in this seminar series — we definitely have to think about how communities are put together. Because communities and how they’re put together are probably as important as the building enclosure and mechanical systems package. Two-thirds of all the electricity in America is consumed in buildings, and that’s pretty important because the electricity is also the pollution-intensive form. People see electricity as some sort of clean energy source; it isn’t in North America. We could make it clean; but we’re not there yet. Right now electricity is the dirtiest form of power, so we’re always trying to minimize it the most, and use it the most efficiently. Purchased energy in buildings alone cost almost 500-billion dollars this year, 2008. Five-hundred billion dollars a year! We could wage a major war in some far-off country for that amount of money. Seven-hundred and fifty-seven million tons of carbon dioxide, which is a pretty large percent of the US total — a little over 8% of the world’s CO2 comes from American buildings. That’s a pretty big number right there. And of course it’s the largest source of sulfur dioxide, which produces acid rain and so on.

Now, we talked about the R-value over a thousand years in a couple of case studies — you know, simple buildings. You look at it and say, “Well, okay, those are just case studies. What is the whole building stock doing?”

Identifying the most efficient buildings

Well, every three years the Department of Energy does a comprehensive survey of commercial and institutional buildings. Ten thousand is the normal sample size. And they ask all kinds of questions about what happens in that building, how people use it, where it’s built, size, date, etc. And they collect the energy use, [most recently] in 2003. So, if you were to know nothing else about a commercial building, when you purchased it, other than its age, then the lowest energy use building would either be the buildings built before 1920 or buildings built in 2000 to 2003 — brand new buildings.

And this is not because buildings built before 1920 don’t have computers in them. If you drive in downtown Boston, you’ll see lots of 1920s buildings have lights, elevators, and air conditioning, all that kind of modern convenience features. This is the energy used in 2003. The difference is that the building enclosure and the building systems used in these older buildings were inherently more energy efficient. And the reason they are inherently more energy efficient isn’t because people in 1920 were smart, it’s because energy was much more expensive in 1920. We forget that. Energy costs in New York City and Chicago at the turn of the century were — depending on the type of energy you’re talking about — were double, triple, quadruple what we pay today. Electricity was quadruple the cost, and heating your building with coal was about double the cost, as it is today.

So those buildings were actually more economically sensible than many of the buildings we build today, even though today we have lots of interesting technologies that allow us to dramatically reduce this number. So this number here is showing eighty-thousand BTUs per square foot per year, and that’s a metric, an energy metric that you can actually measure on your own building. Figure out how much gas you use, how much electricity you use, convert it into BTUs and then divide by the square footage. That’s how complicated it is. And many buildings, you know, good buildings are in the ’30s. Buildings in the ’30s don’t cost a lot.

Better architecture might solve some big problems

So Ed Mazria — how many of you have heard of Ed Mazria? Usually the architects have heard of Ed Mazria because he’s an architect — did a lot of work in the ’70s on passive solar design, and then went back into the hills when oil prices dropped to ten bucks. And in the last few years he’s come back out of the hills and been on this campaign of saying that architecture has the major role to play in controlling climate change because of the energy impacts. And one of the things he’s got is that, well, architecture is more than just the buildings — it affects cities. There are parts of the industrial complex where the office spaces are, and so on, they’re affected by the architecture, and therefore if you add all those components together, he figures about 50% of all the energy consumption in the United States is somewhat under the label of architecture.

And more disturbingly, he finds that the CO2 emissions of buildings has risen faster than any other segment. Industry has actually sort of flattened out. And you’ll notice that it was on a similar trend as transportation and buildings until somewhere in the ’70s — it’s funny, somewhere right around 1973 to ’75 there was a major change in how industry was emitting CO2. Huh, wonder what that might have been? And that was, of course, the first oil crisis, as they called it. And the second oil crisis in ’79 you can also see. Well then the industry had it and they said, you know the writing’s on the wall, energy prices are going to be expensive, we’re going to have to do something about it. And what they did, was people started counting — they had found out how much energy each process used, went around and made life-cycle cost decisions on using premium efficiency motors, and when we should insulate, and the energy consumed has pretty much stayed flat since that time. Largely, but not exclusively. Largely through energy-efficiency measures.

Smarter long-term choices for builders and buyers

The same affect has not happened in buildings because people do not have rational decision-makers when they design buildings. Nobody’s actually saying, “So how much energy am I going to use?” Well, what is the ten-year payback, or the twelve-year payback, on this choice of this electric motor for a fan vs. that electric motor for a fan? And because they don’t make those decisions, our energy consumption continues to go up.

It’s a similar situation in transportation. Trucks have gotten more energy-efficient, trains have gotten more energy-efficient, and planes have gotten more energy-efficient. Personal automobiles have gotten less efficient because people who purchase personal automobiles don’t make rational, economic choices. How else do you explain driving Suburbans to work? You know, the odds of you needing to seat twelve people, or pull a stump out on the way home from work seems pretty low. And rationally you would just rent such a vehicle the one day in three years you need to do so. So those irrational decisions explain both the rate of increase both in transportation, and in buildings. It’s not that it doesn’t make economic or good business sense.

In the residential sector there were some pretty major improvements made in energy efficiency, unlike in the commercial segment. And they were made because of regulation. And before 1950 houses used a lot of energy, and over time the heating, especially the space heating, went down, air conditioning went up, appliances were staying about constant. But major changes were in water heating and space heating. And that trend dropped, or ended in the 1990s. in the 1990s our household energy consumption went up again. And there are a couple of reasons for this. One is that the codes stopped enforcing tighter regulations in the ’80s, so in the ’90s the result came home to roost. The second thing was larger homes. People continued to build larger and larger buildings. And those larger buildings obviously consumed more energy. Even though the household size is still a household, it’s got more square footage. So, again it’s not because we can’t make more energy-efficient buildings, it’s not because it doesn’t make economic sense, it’s because we haven’t chosen to.


  1. AdrienneBurt | | #1

    Unrelated to the content...
    ...but, you may want to not list these Podcasts as "BS Podcast". I know you mean Building Science, but it could mean, ahem, something else.

  2. Boudewijn Piscaer | | #2

    sustainable concrete
    Anybody adressing the sustainable of present concrete? The cement industry is good for 2.4 billion ton CO2 per year and concrete demands 15 billion tons of raw material.
    While concrete can be contributing positively and CO2 levels can drastically be reduced with present technologies, this is not the case, yet.
    From many previous presentations about the subject, we hope to be able to switch to actions in 2010.

  3. Alison Kendall | | #3

    Reducing energy use in existing buildings
    Would like to have you address the challenge of reducing energy use in existing buildings, especially existing single family residential and small commercial and residential buildings. given the current economic crisis, the owners of these buildings are only going to make energy efficiency improvements with substantial subsidies and technical assistance. I would like to see a kind of "Green Corps" of underemployed architects and contractors deployed to give free energy audits to these homeowners, and a series of really substantial and easy to understand national tax and incentive program to fund insulation, window replacement, water and energy conservation and renewable energy improvements. What do you think of that idea?

  4. Alison Kendall | | #4

    Energy Efficiency Models available at low or no cost
    I'm a sustainable building and planning consultant who conducts reviews of existing buildings and planned remodeling projects for small residential and commercial buildings. I have been searching for a good computer based enegy efficiency modeling tool which will help to evaluate the impact of increasing insulation, changing windows and other simple changes in a graphic and intuitive manner which can be used to explain concepts to clients and other designers as well as contractors, mechanical engineers and others. I'm mostly working in California, but some projects in Pennsylvania as well. What would you recommend?

  5. Daniel Morrison | | #5

    You may have more luck in the Q&A section
    Good questions Alison,
    The discussion forum is pretty active so I'd ask these questions there if I were you.


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