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If Walls Could Talk: The Science of Building

If walls could talk, there would be a whole lot of moaning, groaning, and general kvetching.

Jason Forney: In the days when the architect was the master builder, science was an integral part of building design; but in the latter half of the 20th century, architects lost that connection. Through writing, teaching, consulting, design, and an extensive website, your firm, Building Science Corporation, is largely responsible for reacquainting a new wave of architects, builders, and clients with science. Why have you committed yourselves to that endeavor, and why do you think people are listening now?

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Common Molds and Fungi Found in Residential Construction. Click image above to view slideshow.

Betsy Pettit: I was concerned that the architecture profession was giving up a lot of its work to other types of consultants. Architecture is really a combination of art and science, and we architects need to understand how things work in order to come up with an aesthetic that is meaningful for sustainable, energy-efficient, durable projects.

Jason Forney: You define building science as “the study of the interaction between the various materials, products, and systems used in building construction, the occupants of these buildings, and the environments in which they are located.” A lot of people would assume that’s a definition of architecture — or that it used to be. So what happened?

Joseph Lstiburek: I think the problem started when architects came to view themselves more as artists and lost their familiarity with all aspects of construction. I’m appalled in some cases at how architects practice. How can you possibly be an architect and not know the technical side, the physics side, of construction? There should be no place for firms such as ours. If architects do their job, there is no need for another consultant to do the stuff that architects used to do as part of their day-to-day practice because they knew how buildings worked and they knew their materials. Now architecture is mostly art. I love art, but you don’t leave your artwork outside in the rain.

Jason Forney: There is a stereotype that beautiful buildings leak, and efficient, technically well-conceived buildings are ugly. But there’s no reason that needs to be true.

Joseph Lstiburek: You can’t possibly have good architecture without beauty. As an engineer, I approach the problem a little differently. I say the only way buildings are going to last a long time is if people take care of them. The only way that people are going to take care of buildings is if they want to take care of them. And people don’t take care of ugly things; ugliness is not sustainable.

Jason Forney: Sustainability has, in fact, drawn a lot of attention back to building-science issues. What are the overlaps between building science and green building?

Betsy Pettit: A building that’s sustainable is one that is durable, that people can live or work in comfortably, that doesn’t require a lot of intervention to achieve good indoor air quality. And, serendipitously, the things that provide durability, comfort, and good indoor air quality happen to be the things that promote better energy efficiency. That is really where green building and sustainable building should be going. The science helps us get there.

Joseph Lstiburek: I view green as a passing fad. I’ll be happy when it’s over with and we can get back to following the rules of physics and doing architecture in the truest sense: beautiful buildings that stand the test of time, that are structurally sound and therefore safe, that don’t make people sick, that are comfortable and durable. Why do you need a special label certifying that you did what you were supposed to do? Why do architects need to join a special club with an arbitrary and capricious checklist and a secret handshake? I’d be insulted if somebody told me that I had to follow this checklist. That’s why I became a professional. Are we not professionals anymore?

Jason Forney: We’re seeing significant revisions to building codes in response to concerns about sustainability and energy consumption. Do you think codes can drive change?

Joseph Lstiburek: Codes have long ceased to be a means of preventing disasters. They’ve become instruments of social change and government policy. I don’t have a problem with social change and government policy; I have a real issue with building codes as the vehicle for achieving that.

Jason Forney: Can you give a specific example?

Joseph Lstiburek: The thermal-resistance requirements for the building enclosure — we’re now being told what glazing ratios to use. So homeowners who want lots of windows for views and daylight and transparency are forced to build a very different sort of structure, because someone has decided that limiting windows is the prescribed route to lower energy consumption. The codes are consensus documents, but consensus from whom? They are subject to unbelievable lobbying — the process is subject to tremendous political interference. I think people would be appalled at what codes have turned into if they knew how bad the process is. Having said that, I don’t have an alternative.

Jason Forney: What would your code look like if you were in charge?

Joseph Lstiburek: My code would be one sentence: Don’t do stupid things. But the entrenched reality is that codes are political documents. It took me 15 years to get the vapor-barrier provisions changed because of all the politics. Politics in a vapor-barrier discussion? Well, sure: If the code requires a vapor barrier, then you have created a market for a certain set of products that must be used. If the code doesn’t require it, then the market expands to a different set of products. Somebody makes money, somebody loses money.

Betsy Pettit: And we haven’t even mentioned the legal aspects of buildings that had polyethylene vapor barriers. We live in a litigious society. If Building Science Corporation says not only that you do not need poly vapor barriers but also that they can create problems, have we cleared the way for a whole new category of lawsuits? And what does that mean for the profession’s ability to expand its body of knowledge? We should be able to live and learn and evolve. Some experiments are failures, but they help us to learn more about the way things work.

So we have to be very careful about the experiments we make. And frankly, it makes doing research in architecture very difficult. Who pays for it and how? We’ve been lucky to be part of the Building America program, a research program established by the US Department of Energy to promote more energy-efficient housing. Unlike almost every other industry in the country, the building industry, generally speaking, does not invest in research.

Jason Forney: What sort of directive did you receive from Building America?

Joseph Lstiburek: In the early days of the program, the government said, in effect, that things aren’t working and we’re not sure why; go and figure something out. It was as general as that. We said, let’s focus on the failures, which are very expensive, and try to solve them in an energy-efficient way. In other words, try to get a two-for-one. And if the mechanism of solving the problem doesn’t in itself save energy, maybe we can at least save money that we can deploy somewhere else in the project to promote efficiency.

Jason Forney: That’s an interesting way to think about a project — in terms of redistributing savings to rearrange the budget.

Joseph Lstiburek: Only an architect can connect the dots in that way. This is important. Think for a moment about the perspective of typical homebuilders. How do they figure out how large a heating or cooling system a house needs? They ask a mechanical contractor to size the system. Mechanical contractors have absolutely no incentive to make the system smaller. They make money based on the number of tons of installed cooling capacity. So there’s no reason for a mechanical contractor to say, “You know, if you use better windows and maybe make them a little smaller and move them from here to there, I can save you two tons. So maybe you spend $2,000 more on windows to save $3,000, but you’re still $1,000 ahead.”

Incentives get even more skewed when you talk about construction at the scale of the production homebuilders. One of the legends in the homebuilding industry is Bill Pulte; his company is one of the largest homebuilders in the US. He explained it to me pretty clearly: the science and physics of building is a complete distraction. In fact, constructing a house is completely incidental to their real business, which is pushing the property and financing package. It’s all about impressing Wall Street.

The only solution lies with architects. But now we have a gazillion consultants because the architecture profession today doesn’t have enough generalist knowledge to ride herd on everybody. Architects need to be more in control. They need to know enough so they can push back when a mechanical engineer or a structural engineer gives them colossally stupid advice. That probably sounds surprising, coming from an engineer. But I want architects to have more knowledge and more power. They don’t have to know everything, but they need to be good general practitioners.

Jason Forney: Some residential architects are headed in that direction, optimizing energy performance with the Passive House standard and the net-zero-energy concept.

Joseph Lstiburek: If you want to have an R50 slab insulation, I think that’s fabulous. If you want to have an air-tightness requirement of .6 air changes per hour at 50 pascals, knock yourself out. But when you run around saying anything less than R50 and .6 is dumb, I get irritated. There is a difference between private standards and labeling, which can be helpful, and mandates. I believe that certain decisions and tradeoffs should be left to the client and the architect. Of course there should be an energy code, but its requirements should make sense. The code shouldn’t push beyond technology’s ability to respond, which is what’s happening now. We don’t yet have the industrywide delivery mechanism to achieve some of these targets on a large scale.

Jason Forney: Do you think there’ll be a point in time when that changes? When either the cheap oil era has really ended, or energy costs increase so dramatically that changes are forced on us?

Joseph Lstiburek: In fact, on a square-foot basis, houses in the United States and Canada have improved dramatically in the last 30 years. But houses in general haven’t saved energy, because the houses have gotten bigger. So we have all of these wonderful improvements in technology and efficiency, but we’ve managed to find some way to squander every one of them. We now have efficient heating, cooling, windows, and enclosures, and I suspect house sizes have maxed out. So how come we’re still using so much energy? Well, have you ever looked at what we put into a house? The televisions, the computers — all of the consumer stuff that’s plugged in and never turned off. Betsy just worked on a house where the miscellaneous electrical loads are larger than either the hot-water load or the space-heating load.

Betsy Pettit: It was a house with three boys, who are all into gaming and technology. But at some larger level, these are moral questions that people need to struggle with individually. It’s not the job of the architect to impose the answers. But we can build holistically and efficiently, and help people make smart tradeoffs.

Jason Forney: In the introduction to your Builder’s Guide series, you talk about the loss of knowledge and the reliance on following convention, when people don’t understand why or how the methods that they’re using work. Sometimes the science exists, yet it’s still ignored. That’s a lot of inertia to overcome.

Joseph Lstiburek: We don’t teach fundamentals in school anymore, so people seem to be incapable of sorting through the nonsense.

Jason Forney: Betsy, a lot of your recent work involves transforming homes through deep energy retrofits. But there are millions of existing homes. It’s a huge challenge just to know how to begin to evaluate them.

Betsy Pettit: And we don’t have the total answer. It’s much easier to figure out a way to build new buildings after learning from the forensics why things fail. But the problem of existing buildings is that each one is a research project in itself; none of them are the same. We are working with National Grid and the Commonwealth of Massachusetts on the Deep Energy Retrofit pilot program; they really want these retrofits to be affordable, and they want to be able to implement them by component. Right now, we’re not comfortable with not understanding the whole house. We believe that a plan needs to be made for the whole building before we can think about ways to implement it incrementally.

So we have a demonstration project with whole houses. We’re hoping that we’ll learn from that process how to do it less expensively and how to make a kit of parts that will give homeowners some options: Here’s how to waterproof and insulate your basement. Here’s what you can do to your attic. Here are ways you can change your windows. These techniques can be applied to larger buildings, too, although those projects tend to have consultant teams. Houses are the bigger problem.

Jason Forney: Historic buildings present another set of challenges. How far should we be pushing changes in appearance to historic buildings for the sake of increased efficiency?

Betsy Pettit: One of the most controversial issues in historic structures is windows. Old window technology is terrible compared with new windows. The argument is over aesthetics; I don’t believe that the difference is huge but, obviously, some people do.

Joseph Lstiburek: It’s a political, moral, and philosophical judgment. I can put windows back into a building that are exactly what I took out, without improving them. Or I can install windows that are significantly technologically superior that look very similar. I understand the arguments for the old windows, and I know the new ones aren’t the same. But what are we trying to accomplish here? Especially when taxpayers’ money is involved through tax credits. I think it’s appalling that taxpayers’ money is being used to subsidize energy inefficiency.

Betsy Pettit: And sometimes decisions are made on the basis of outdated or incorrect information. Our office is in the Somerville Historic District, so we needed permission to change the windows. We knew they would be wood; we wanted low-E glass, which was not allowed because early low-E had a purple tint. That’s not an issue anymore. I had to bring in sample sashes to convince them, and we ultimately got permission.

Jason Forney: Another controversy in this region is insulating masonry buildings. Why are so many architects afraid to add insulation to the inside of masonry walls?

Betsy Pettit: We’ve told people that you could potentially change the way the brick sheds moisture, and you could ruin your brick. So there should be some fear about that. But we’ve got mill buildings all over New England. Probably every architect in the region has at some point turned a mill building into housing of some sort. Why in the world would we think that it’s not OK to insulate the brick wall?

Joseph Lstiburek: It’s irrational hysteria. Yes, there is some level of risk in insulating a masonry building on the interior, but it’s been overblown. If you control the way rainwater is handled by the surface of the building from the outside, the risk is trivial. I just did a project in Vermont, a 100-year-old masonry building. You could see the problems from the parking lot: a stain under every window and at the parapet, which meant those were the areas with water issues. I told the owners to rebuild the parapet, and then pull out the windows, pan-flash them and give them drip edges, and then put them back — because they needed the historic tax credit. So regardless of the thermal performance of the window, they could resolve the water management problem and safely insulate the interior.

What I loved about that project was the architect, who was grinning because the clients had paid to bring in the outside expert to tell them exactly what he had already been saying. This is an architect with a world of experience, and he knew what he was talking about: You keep the water out, you keep it from collecting where roofs and walls come together, and you can insulate as much as you want. Once you handle the water, everything else is secondary.

Jason Forney: Your last 30 years have been, in effect, one big research project. What are your conclusions at this point?

Betsy Pettit: Buildings are complex structures. Things happen that you can’t anticipate. So I never brag about projects while they’re only on paper; I like to wait until they’ve been built for at least a few years. What we don’t do enough as architects is go back to our buildings. Of course, we don’t get any money to do that, generally speaking, so it’s tough. Nobody would pay for pure building-science research if we didn’t have public funding. We are thankful to have the government as a client who will pay us to do the research that architects and engineers are benefiting from. We’re doing our best to make that information available through our website and teaching.

Joseph Lstiburek: Thirty years ago, I thought I was a really clever guy who knew everything; now I’m an older guy who is convinced that he knows significantly less than what he thought he knew. I’ve discovered that ignorance truly was bliss. With the lens of experience, I know that a lot of issues are not as black and white as people like to think they are. There’s a lot of gray. But I do know this: You can’t substitute the judgment of the architect or the engineer with a computer simulation program and a checklist.