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Building Science

Why Does Green Building Matter? (Part 2) – Building Science Podcast

Improving our buildings is the cheapest way to deal with pollution, energy, and resource issues

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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 episode, Dr. John discussed how, in the middle of the 20th century, cheap energy allowed us to build wasteful buildings. In this show, he explains how improving energy efficiency in buildings is the most affordable way to address global energy and climate concerns. He also lists his core green building strategies.


This seminar is not about how to produce cheap, clean energy, but it is about how to save energy. And one of the reasons it’s about saving energy is that’s the lowest-cost, lowest environmental impact approach to solving the energy security climate change problem. There’s not much argument about that by anyone who’s putting numbers to it, but it’s a lot easier and sexier to buy a photovoltaic panel and throw it on the roof. But often the least sexy and harder approach is the best one.

Buildings should already be better than they are

The International Panel on Climate Change—the people who give you dire predictions on how the water levels are rising—also have done a report on what could we do as a society on the planet to reduce CO2 emissions and what it would cost. They looked at all of these categories, including buildings, and said, “So, what would it cost at $20 a ton—how many tons of CO2 could we save at $20 a ton?” No matter what price you put on carbon, buildings are the biggest form of saving CO2 emissions. So you could reduce human output of CO2 on the planet by 20% for a cost of less than $20 a ton just by doing buildings. The other thing about buildings is that they’re the lowest-cost way of reducing CO2. If you want to reduce CO2 by having more fuel-efficient cars, it’s going to cost more. In fact, even at really expensive levels, it’s hard to reduce emissions of CO2 in the transportation sector. You can do it in the agriculture sector, but you can’t do it in the transportation sector. Buildings, on the other hand, at the lowest-cost increment, will save the most amount of CO2. One of the lines that I liked out of this study that the Economist magazine also repeated and quoted is that when they looked at it, buildings appear to be currently irrationally designed, and economically they should already use less energy than they do—with no carbon tax at all—and that’s absolutely what we see when we look at our building designs. And it’s like, well, but that doesn’t even make sense today, with gas at 11 dollars a therm and electricity at 10 or 12 cents a kilowatt hour—and yet we continue to do it. It’s mostly a disconnect of what can be done at what cost to reach what end.

Some people understand the value of energy efficiency

Another Chevron ad here is saying the good news is that we’ve got a huge source of alternative energy; it’s called conservation. Does anyone find it interesting that one of America’s largest oil companies is putting in ads in major newspapers saying you should save—don’t waste—save oil? You think maybe they know something that we don’t? We have actually had tremendous progress in industry in reducing energy consumption for output. We already have the energy content of all of our industrial output. In the same time period, Japan has reduced the energy content of its economy by a factor of 4. One of the reasons that Japan doesn’t care too much about energy prices going up, especially oil, is that they’re using less oil every year. Per GDP output, they don’t use much oil, so it doesn’t impact their lives that much. If you’re in England and you’re paying 7 dollars and 50 cents a gallon, the fact that the price goes up 50 cents a gallon, well, it’s not really noticed much. When you’re paying 3 bucks and it goes up 50 cents, you actually notice. So, a lot of countries are much better equipped to handle these increases in energy costs than is America. Countries that are least able to handle it are always the same: the poor ones in sub-Saharan Africa, and Bangladesh. They’re the ones that are actually being hit the hardest. Now, Royal Dutch Shell is the second-largest privately held oil company in the world, and recently they’ve been rattling the chain as well. This is from a letter to the editor of the London Times saying efforts to fight global warming will be wasted unless we concentrate on energy efficiency. Again, second-largest oil company on the planet, writing letters to the editor saying you’ve got to focus on energy efficiency. I think this is unbelievable, and no one seems to be paying attention—that this is a huge shift in mentality on the energy-supply side, huge.

A lot of room for improvement

What we do notice is the price of gas going up, and they’re connected. So basically, easy oil is done. If we switch to coal, we cause more of a CO2 problem. So the easiest, lowest-cost, biggest-impact thing we can do now is stop being stupid—meaning, stop the waste. Ninety-five percent of all the energy that enters the American economy is wasted; 95%. Now, we’re doing better than that here, because you can notice that these lights here are incandescent bulbs, and therefore they’re about less than 2% efficient at converting electricity into light. If you look at the typical mix of America’s energy electricity production, it’s about 30% efficient; so, 30% efficient times 2% efficient—yeah, it’s about 0.7% efficiency. So, from coal to light, 0.7% efficiency. Wow, that sucks doesn’t it? Now, in this particular example, we could multiply that by 5 by replacing the fryer bulbs that are keeping us warm and keeping the air conditioner running, with compact fluorescents, and that would make economic sense the day they were installed, because the moment that this thing with a 2000-hour life had to be replaced, the labor cost of that first replacement pays for the whole CFL. Forget energy. It’s got nothing to do with energy. Just the replacement and labor costs. But do we have incandescent bulbs in here? Yep. Why? Cause…what is the answer? Cause we’re stupid. I can’t really think of any other explanation as to why we would be putting incandescent floodlights that we then cover half the light output on and bounce off a dark-colored surface—because if we actually looked at the efficiency of lighting the table, that .7% number I just calculated? Probably cut it in half again. So when you look across the economy and you look at all kinds of processes and things that we do, 95% is an optimistic number that we throw…we’re 5% efficient. And it’s pretty easy to be 20% efficient. That’s a lot of room to move; that’s the good news. The good news is that we actually can solve the problem. The bad news is that we really haven’t been doing anything.

Not all green buildings are sustainable

How does this connect to green buildings? Well, first of all, green buildings recognize that there’s an issue going on here. There’s a whole bunch of agendas that are being satisfied by a green-building label, but a sustainable building or sustainable society is one that can be sustained or continued to be produced for the long term without adversely affecting the conditions necessary to support the same activities in the future. That’s a real definition. Green we can argue about; sustainable, it’s right in the dictionary. We know what it means. And we’re nowhere near building sustainable buildings. When I hear that term, it’s like, “My god, are we going to dilute that brand as well?” The green brand has already being diluted, and a lot of people are skeptical. But don’t screw up what is actually a well-defined term called sustainable and say, “I’m making a sustainable building.” No, I’m building a more sustainable building. My building is net-zero energy or something like that, but it sure ain’t sustainable. But what we could do is minimize nonrenewable energy and resource use, and that might be a greener building than our current buildings. Who knows? What we do know is that green buildings are durable, because if they last twice as long, they use half as many resources over their life. Pretty simple. That’s an easy one. But, of course, to be able to be used for 50 years they also have to be functional. If you don’t design a building that is able to be functional, what’s the sense of having it in the first place? And, of course, that’s where the beautiful comes in, too. People will look after and want to use it.

So, how does this connect to green buildings? Well, building science is the science of making buildings that work. It’s not in the dictionary, because if you look up building science in the dictionary, you won’t find an entry since building science really isn’t that common. But our definition is making buildings that work. And green buildings are buildings that work better than normal. They work well. They’re more durable, they’re more energy efficient, they’re more comfortable, they’re more healthy. They just do a good job of being a building. The confluence of those things is where building science lies on the green side. The normal kind of building work that we do that isn’t green is concerned about energy and comfort and rot and mold and corrosion and not getting sued and being cheap to build and not burning down. But there’s a huge overlap with the green side of reducing energy consumption, making a durable building, using materials that are sensible. And the building science is, in essence, inextricably connected to the green buildings.

Several steps to building green

Here are my strategies for green buildings. We tried to put them all on a slide, which of course is impossible, but… first of all is keep it simple and keep it small. Well, that would be pretty easy. By simple we mean compact shape ideally, but we also mean keep it simple so that’s there’s not too many widgets, gadgets, and things that can go wrong and break down. And oriented, respecting the sun and wind and rain. Then reduce your heat loss and gain, which means lots of insulation and avoiding thermal bridges; use very good windows; make a building airtight and then ventilate to the appropriate level. Then we avoid energy use by using efficient appliances. And always remember the most efficient appliance is one that’s turned off.

There’s probably a little over an average power plant being used right now in America, total, to light stairwells where no one is. So even if I put fluorescent bulbs in every stairwell where no one is in America, that’s not very efficient because no one’s there. It’s 0% efficiency by definition. You have to be able to turn things off when no one’s around. Fans have to be turned off, lights have to be turned off, etc. We use daylighting and motion sensors to achieve that. It’s not just about getting a premium-efficiency motor, it’s having a control system that turns it off; because the most efficient thing is, one, turn off the control, guys, right? So then we have durability—and drains, airtight, and drying are what I put down as durable (and we’re going to talk a lot about that aspect throughout this seminar), and then and only then do we generate renewable energy. It makes no sense to put on photovoltaics or even solar hot water until you’ve done all of these things. And small wind turbines—the ones that are this big around—make less sense than even photovoltaics because the physics require that they be large. You might have noticed that most commercial wind turbine projects use really big, large turbines because that makes them efficient, and efficient means they are less costly. Now, efficient makes them greener, right? Fewer materials used for electricity generated. A whole bunch of little 8-ft.-diameter wind turbines is actually not very green. You’re better off pooling your resources and getting big wind turbines. That’s a much greener and economic and sensible thing. It’s also more economical to put lots of insulation in.

Tighter buildings are still cheaper than solar panels

So, the basic strategies are always you start off with building shape and orientation, which costs nothing except design effort at the napkin stage. As soon as you reduce energy consumption in a building dramatically, it makes sense to use renewables. Right now, we would say that electricity from photovoltaics in Massachusetts—no subsidies or anything like that—costs around 50 cents a kilowatt hour. That’s expensive. On the other hand if you were to reduce your energy use by a factor of 3, your total energy bill wouldn’t change from what you already pay, because even though the cost per kilowatt hour is high, you use a lot less kilowatt hours. And those two things have been converging for some time, by the way. Normal electricity costs have been going up, renewables have been coming down, and people have been able to figure out how to use a lot less electricity. So it makes some sense to keep your electrical bill—you could actually keep your electrical bill the same and use photovoltaics if you really went far enough. We’re not quite there, but we’re close; with subsidies, we are there.

When renewable energy makes economic sense

Now, given the existing stock of buildings, we’re going to have to retrofit a lot, and that gives us opportunities to do renewable energy and to reduce the loads dramatically. This is a plot showing 15% per annum growth in renewable energy. I’ll let you know that photovoltaics and wind power have been growing more than 20% to 30% per year. So, the growth rates for the last five or seven years have been well higher than 15% per year. And that compound interest means they could produce a significant chunk of the electricity that’s needed in this country. But at the same time we have to reduce the energy consumption of our buildings. So, the energy consumption typically grows at around 3% per annum—2% to 3% per annum—and has for the last while, and that’s the red line. What we have to do is build in efficiency gains of around 4% per year, and then the two things will converge in 25 years. Renewable energy can provide a majority of the energy required by our buildings if both of those strategies are employed. It’s the combination that’s powerful. Of course, even beyond 2035 or so, we should be moving from the paradigm of doing less evil, which is where we are right now—let’s make our buildings pollute less, let’s make them less stupid—to make them smart. Move from the turd-polishing to make them jewels. That is a hard job, and people are just dabbling in the research community, but it’s probably not something where anyone needs to go out and build a whole bunch of buildings. We have to figure this out. We’ve got a lot of normal buildings that we can do a lot easily on.

So, producing energy, cleaning air and water—that’s one of the things green roofs are supposed to do, right? You can actually clean some of the air and water around the building, enhance the local ecology—you know, let raccoons live on your roof. Reuse materials, use materials that are low-impact recycled, that don’t use as much energy. But that’s really far down the road. We’ve got a lot of problems to solve in the next three months, let alone the next three years, that are much more fundamental. Clearly, cheap oil is running out. There could be some pretty profound changes, and maybe right now we’re in the midst of that. Energy security is a real challenge, particularly when you think about climate change limitations. By definition, green buildings use fewer resources over their life—over the expected design life. One of the ways to know that is to count. How much energy, how many yards of concrete—that’s one of the ways to assess this. So, just for someone to say they’re green is about as useless as just saying they’re green. It doesn’t mean anything. Everyone’s green. And then, efficiency and renewables, which are going to be the path forward—at some point, that’s where we’re going to put all of our efforts—will require lots of retrofit and will require a lot higher efficiency than we already have in our buildings. We need to take our buildings to a much different level: Somewhere between reducing energy consumption by one-half to two-thirds is where we probably should go before we start putting a lot of effort into renewables. But when you do that you can get some pretty nice combinations.



    Dr. Joe in North Carolina Nov 9th
    Joe will be speaking in North Carolina at the Home Builders Association of Charlotte 8 am - 3:30 pm on November 9th.

    For more information:

  2. IBHS | | #2

    John Straube
    Dr. John Straube will be the keynote speaker Dec. 1 at the Institute for Business & Home Safety's Going Green and Building Strong conference in Palm Harbor, Fla. Register at

  3. kooldave | | #3

    The word sustainable
    I have read the magazine Green Builder and the word sustainable is used all to frequently but I could not be comfortable with its context relitive to the surrounding paragraphs. Thank you for your thoughts reative to this subject.

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