Peter Yost is a building scientist and regularly blogs at Green Building Advisor. A recent post of his chronicled his adventures dealing with some sort of bio-organic growth on the recently added siding at his home — but just at the south side, not the north.

Mr. Yost’s wife first noticed the issue and began the conversation as follows:

“OK, Mr. Building Scientist, you supposedly worked your moisture magic when you re-sided the house with clapboards[…] But I am looking at little black dots all over the siding. It looks a lot like mold to me.”

You’ll want to read the full post for details, but the Reader’s Digest version is that some species of mold or mildew was relying upon the oil in the oil-based paint as a food source, rather than his wood siding. Here are some of his lessons learned:

  • Keep your eye out for oil-based primer on exterior wood trim and cladding. It’s great to order materials that have been factory-primed, but what they use can make a difference.
  • Beware of potential problems when you install a latex topcoat over an oil-based primer. If you are in any sort of “wet” climate (generally more than 20 inches of precipitation annually), these are probably not a good mix.

Energy modeling is not exactly a brand new science, but it certainly hasn’t been around very long, either.

In essence, energy modeling is a software-based approach to predicting how much energy a given building will use based on its location, orientation, wall/roof/slab design, windows, doors, etc. In California, for example, energy modeling is a critical aspect of designing any project and carries a great deal of influence on the permitting process. In Europe, there are very real country-wide energy usage agreements that set measurable goals for building performance. (more…)

Debra Rubin, of ENR, shares the sad news of the passing of an AEC forensics grandmaster:

John M. Hanson, who, as president, helped guide the growth of Wiss, Janney, Elstner Associates Inc. into an industry-leading forensics and failures engineer and who led probes into high-profile collapses of the Kansas City Hyatt hotel walkway in 1981 and the New York State Thruway Schoharie Creek Bridge in 1987, died on May 26 in Green Valley, Ariz., at 84. The firm did not release the cause of death.

(more…)

Astrophysicist and author Ethan Siegel, writing for Forbes, just helped to expose a longtime myth about good ole’ Galloping Gertie, a bridge that (in)famously collapsed just a few short months after opening to public traffic.

To help jog your memory, here is footage uploaded to YouTube of the bridge twisting and bouncing around:

The story we learned in Physics class back in school was that Galloping Gertie’s fatal flaw was related to “resonant frequency” — the same phenomena responsible for wine glasses shattering when exposed a tone of specific frequency. Siegel proposes an alternative explanation:

But it wasn’t resonance that brought the bridge down, but rather the self-induced rocking! Without an ability to dissipate its energy, it just kept twisting back-and-forth, and as the twisting continued, it continued to take damage, just as twisting a solid object back-and-forth will weaken it, eventually leading to it breaking. It didn’t take any fancy resonance to bring the bridge down, just a lack of foresight of all the effects that would be at play, cheap construction techniques, and a failure to calculate all the relevant forces.

This wasn’t a total failure, however. The engineers who investigated its collapsed began to understand the phenomenon quickly; within 10 years, they had a new sub-field of science to call their own: bridge aerodynamics-aeroelastics. The phenomenon of flutter is now well-understood, but it has to be remembered in order to be effective. The two bridges currently spanning the Tacoma Narrows’ previous path have shorn up those flaws, but London’s Millennium Bridge and Russia’s Volgograd Bridge have both had “flutter”-related flaws exposed in the 21st century.

Don’t blame resonance for the most famous bridge-collapse of all. The true cause is much scarier, and could affect hundreds of bridges across the world if we ever forget to account for, and mitigate, the fluttering effects that brought this one down.

Read all of Siegel’s piece for the details…

Patrick Sisson, writing for Curbed, wrote a wonderful article: How air conditioning shaped modern architecture — and changed our climate. He states:

Air conditioning enabled our great modernist buildings to rise, but it’s also fueled today’s energy and environmental crisis. AC helped create a new building typology, one that environmentally conscious architects and designers are trying to move beyond with new designs and passive-cooling techniques.

“Modern buildings cannot survive unless hard-wired to a life-support machine,” says University of Cambridge professor Alan Short. “Yet this fetish for glass, steel, and air-conditioned skyscrapers continues; they are symbols of status around the world on an increasingly vast scale.”

Interestingly (at least to me), the development and implementation of air conditioning and mechanical ventilation was not primarily driven by a desire for improved occupant comfort. Instead, the focus was health:

The new class of white-collar workers who occupied these upper-level offices suffered through humid summers not just because they didn’t know any better, but because Victorian social mores didn’t place much stock in personal comfort. In fact, the adoption of mechanical ventilation systems, which were invented by Benjamin Franklin Sturtevant in the 1860s and became more common in taller buildings towards the end of the 19th century, was due in large part to the problems of heat and light—coal- and gas-powered lamps and heaters quickly filled rooms with toxic smoke—and the belief that poor health was caused by miasma, or dirty air.

Still, at the time, ventilation was less about a comforting breeze and more about sanitation—removing humid, fetid air from crowded workshops and workspaces. By the mid-1890s, designers and architects in New York needed to file their building plans with the Bureau of Light and Ventilation. The 21-story American Surety Building in New York, built in 1896, included a ventilation system, but only for the lower seven floors. Workers on these levels couldn’t open their windows due to the dirt, muck, and grime of the city streets.

I find it amazing that a little over 100 years after Carrier installed the first building air conditioning system that we have seemingly come full circle.

Britain has a problem. Chances are, the problem that Britain is facing also affects many jurisdictions in the US. What is this problem?

Energy modeling — the process of using sophisticated software to predict future building performance — isn’t as accurate as some industry professionals would like to believe. In other words, the supposed energy efficiency gains that should be realized by implementing specific strategies are not matching real world performance results. And since energy modeling is often tied to various financial and other incentives, as well as driving major design decisions affecting thousands of recently constructed buildings, this is causing quite the controversy, and should be a real cause for concern here in the US.

The Telegraph has more on a study by researchers at the University of Bath:

The researchers found that the building modelling professionals could not agree on which aspects were important and which were not, or how much difference to the energy bill changes to them would make. A quarter of those interviewed were judged to be no better than if a member of the public had responded at random.

[…]

Co-investigator and Senior Lecturer in the Department of Psychology, Dr Ian Walker added: “Given our findings about how the level of relevant education and experience don’t separate the good modellers from the bad, we are calling on the government for educational and policy change to work with industry and universities to increase efforts in improving building physics education.

The UK Green Building Council, the British counterpart to the USGBC, added the following:

John Alker, Director of Policy & Campaigns at the UK Green Building Council said: “ “There is no doubt that the majority of buildings do not perform as they were designed to do. This is widely known in the construction sector, and it is something that the industry needs to get to grips with.

“The so-called ‘performance gap’ occurs for a variety of complex reasons, and needs action by all those involved in the property life cycle – such as architects, engineers, contractors and facilities managers – not just building modelling professionals.

There are some in the building industry — perhaps even a majority of people — that believe concrete is either waterproof, or that it is somehow immune to any negative effects from exposure to moisture. However, typical concrete is porous, with many tiny cracks, allowing water to penetrate. Exposed to freeze-thaw weather cycles, that water can cause the existing micro-cracks within the crystalline structure of the concrete to expand, and ultimately weaken the assembly’s integrity allowing for much larger cracks.

If only there was a concrete that could resist water, and minimize cracking.

Under the direction of civil engineering professor Konstantin Sobolev, researchers at the University of Wisconsin at Milwaukee think that might have something for the building industry that will do just that. Laura Otto at Phys.org has more:

Super-strong polyvinyl alcohol fibers or high-density polyethylene fibers, each the width of a human hair, are mixed into the concrete and bond with it. When cracks begin, the fibers prevent them from opening and becoming larger gaps.

In fact, Sobolev isn’t trying to eliminate cracking. He wants to direct the process in a preferred way, resulting in evenly distributed microcracking. This disperses the load so that tiny cracks remain small while the material’s superhydrophobic features form a water barrier.

This architecture, Sobolev says, allows the material to withstand four times the compression of traditional concrete and have 200 times the ductility, or flexibility under stress.

Since science is more fun with a video, here is the professor and postdoctoral researcher Marin Kozhukhova demonstrating some of their findings:

Guess it all depends on the criteria being used to define what “perfect” really means, but if there is one person on this planet of ours that might have a clue what the perfect wall is, it is Joseph Lstiburek. At the wonderfully named Let’s Fix Construction website, building scientist extraordinaire Lstiburek contributed an article with the bold title, The Perfect Wall.

In truth, the article goes well beyond the scope of describing what a “perfect” wall might be, and could instead be titled, The Perfect Building Envelope. Besides walls, Lstiburek also diagrams the components of the perfect roof, the perfect slab, as well as providing several variations on wall design options.

Getting back to the definition of what a perfect wall actually is, here is the introduction:

The perfect wall is an environmental separator—it has to keep the outside out and the inside in.  In order to do this the wall assembly has to control rain, air, vapor and heat. In the old days we had one material to do this: rocks. We would pile a bunch or rocks up and have the rocks do it all. But over time rocks lost their appeal. They were heavy and fell down a lot. Heavy means expensive and falling down is annoying. So construction evolved. Today walls need four principal control layers—especially if we don’t build out of rocks. They are presented in order of importance:

  • a rain control layer
  • an air control layer
  • a vapor control layer
  • a thermal control layer

A point to this importance thing here, if you can’t keep the rain out don’t waste your time on the air. If you can’t keep the air out don’t waste your time on the vapor.

You’ll definitely want to read and bookmark the full article. Just be prepared — this is some seriously geeky building science content. But what else would you expect from the founder of the Building Science Corporation?

Ronald Ray, writing for Construction Specifier, has a great article on different methods for detecting, diagnosing and pinpointing the location of leaks within various types of roofs. What makes Ray’s article so great is some of the cool new technologies outlined representing the bleeding edge of building forensics:

All roofs eventually leak—it is just a matter of when and where. Nevertheless, the hope is that new roofing systems do not leak right from the start. It is critical to verify the watertightness of roofing, especially if it is to be covered with ballast or a vegetated roof assembly. This verification is a field quality-control measure beyond the scope of a roofing manufacturer’s visual inspections for issuance of a warranty. For existing buildings being considered for a reroofing program, conducting a roof survey to determine the location and extent of wet substrates is essential to making fiscally responsible decisions related to the program’s extent…

Other technologies, such as electronic leak testing, can detect leaks with far more reliability than flood-testing. Some electronic leak-testing methods include:

  • electrical capacitance/impedance testing;
  • infrared thermography;
  • nuclear hydrogen detection;
  • low-voltage electrical conductance testing; and
  • high-voltage spark testing.

Building Information Modeling, or BIM, is a method of designing buildings using sophisticated 3D software that makes it much easier to visualize how various components and systems come together in a 3D space and how they will interact or interfere with one another. Perhaps most importantly, BIM facilitates identifying potential conflicts/defects prior to construction, and is a very powerful tool for sustainability by supporting the integrative design process.

Unfortunately, the construction industry isn’t exactly well-known for its rapid adoption of the latest technologies and the majority of A/E/C firms have yet to implement BIM as part of its workflow. Since few A/E/C professionals use BIM, even fewer are going to be able to articulate the benefits of using BIM to building owners.

For that reason, the National Institute of Building Sciences (NIBS) has developed the National BIM Guide for Owners. Here’s what they have to say about it:

A building information modeling (BIM) guide for building owners has been developed under the auspices of the National Institute of Building Sciences. The National BIM Guide for Owners is a new guide that building owners can adopt to provide a documented process and procedure for their design team to follow in order to produce a standard set of BIM documents during the design and construction of the facility, and for maintenance and operations of the facility upon handoff. The National BIM Guide for Owners is based on the foreign, federal, state and local BIM guides that currently exist, but geared to a generic facility with uniform requirements for use by a variety of government, institutional and commercial building owners. It references a range of documents and practices, including those contained within the National BIM Standard-United States® developed by one of the National Institute of Building Sciences’ own councils, the buildingSMART alliance®.

You can download the full guide in PDF format directly from NIBS.